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(1) combined processes (such as sublimation, fusion or melting, evaporation) which remove snow or ice from the surface of a glacier or from a snow-field; also used to express the quantity lost by these processes (2) reduction of the water equivalent of a snow cover by melting, evaporation, wind and avalanches.

the area of a glacier where more glacier mass is lost than gained.

depressions in the snow surface caused by the sun or warm, gusty wind.

mound or layer of moraine in the ablation zone of a glacier; the rock has been plucked from the mountainside by the moving glacier and is melting out on the ice surface.

period during which glaciers lose more mass than they gain; usually coincides with summer.

area or zone of a glacier where snow and ice ablation exceed accumulation.

the difference, taken without regard to sign, between the values of two variables

the difference between the measured or inferred value of a quantity and its actual value.

(1) the ratio of the mass of water vapor to the volume occupied by a mixture of water vapor and dry air (2) mass of water contained in a unit volume of moist air.

growth of a cloud or precipitation particle by the collision and union of a frozen particle (ice crystal or snowflake) with a super-cooled liquid droplet which freezes on impact.

all processes by which snow or ice are added to a glacier, this is typically the accumulation of snow, which is slowly transformed into ice; other accumulation processes can include avalanches, wind-deposited snow, and the freezing of rain within the snow pack.

area of a glacier where more mass is gained than lost.

period during which a glacier gains more mass than it loses; usually coincides with winter.

area of a glacier where more mass is gained than lost.

the extent to which the readings of an instrument approach the true value of the calculated or measured quantities, supposing that all possible corrections are applied.

rain or snow containing acidic substances, resulting from the atmospheric pollution mainly with sulfur and nitrogen; acid precipitation has a lower pH than unpolluted rain.

a foundation pile on which a cold air refrigeration system has been installed to remove heat from the ground.

special design and construction methods used for engineering works in permafrost areas where permafrost degradation cannot be prevented.

an ice wedge that is growing as a result of repeated (but not necessarily annual) winter cracking.

the layer of ground that is subject to annual thawing and freezing in areas underlain by permafrost; also known as seasonal frost.

a foundation pile on which a liquid coolant refrigeration system has been installed to remove heat from the ground.

a mass of rock fragments and finer material, on a slope, that contains either an ice core or interstitial ice, and shows evidence of present movement.

the process by which characteristic landforms are currently developing as a result of thawing of ice-rich permafrost or melting of massive ice.

a general term referring to several forms of slope failures or failure mechanisms commonly occurring in the active layer overlying permafrost.

the thickness of the layer of the ground that is subject to annual thawing and freeing in areas underlain by permafrost.

the tensile or shear strength which has to be overcome to separate two objects that are bonded together by ice.

the process by which two objects are bonded together by ice formed between them.

when a mountain glacier's terminus extends farther downvalley than before; glacial advance occurs when a glacier flows downvalley faster than the rate of ablation at its terminus.

the horizontal transfer of air mass properties by the velocity field of the atmosphere.

fog which forms in the lower part of a warm moist air mass moving over a colder surface (land or water).

non-gaseous substances, divided into solid particles or liquid droplets, held in suspension in the atmosphere.

the additional ground ice formed as a direct result of permafrost aggradation.

the cumulative number of degree-days below 0° C for the air temperature during a given time period.

an extensive body of the atmosphere in which physical properties, particularly temperature and humidity, exhibit only small and continuous differences in the horizontal plane; it may extend over an area of several million square kilometers and over a height of several kilometers.

the ambient temperature indicated by a thermometer exposed to the air but sheltered from direct solar radiation, or placed in an instrument shelter 1.5 to two meters above ground; also called surface temperature.

the cumulative number of degree-days above 0°C for the air temperature during a given period.

a large depression of the ground surface produced by thawing of a large area of very thick and exceedingly ice-rich permafrost.

a non-dimensional, unitless quantity that measures how well a surface reflects solar energy; ranges from 0 - 1; a value of 0 means the surface is a “perfect absorber,” where all incoming energy is absorbed, a value of 1 means the surface is a “perfect reflector,” where all incoming energy is reflected and none is absorbed.

a low centered on the eastern slope of the Canadian Rockies in the province of Alberta, Canada.

the low pressure center located near the Aleutian Islands on mean charts of sea level pressure during the winter; it represents one of the main centers of action in the atmospheric circulation of the northern hemisphere.

refers to high mountain areas above the timber line (where trees cease to inhabit extremely cold environments).

a glacier that is confined by surrounding mountain terrain; also called a mountain glacier.

annual accumulations of snow and dust on a glacier.

the lowest altitude at which mountain permafrost occurs in a given highland area outside the general permafrost region.

the vertical subdivision of an area of mountain permafrost into permafrost zones, based on the proportion of the ground that is perennially cryotic.

a principal middle level cloud type (cloud genus), white or gray, or both white and gray, which occurs as a layer or patch with a wave aspect, the elements of which appear as laminae, rounded masses, rolls, etc; these elements usually are sharply outlined, but they may become partly fibrous or diffuse; they may or may not be merged, and they generally have shadowed parts; most of the regularly arranged altocumulus elements have an apparent width of 1 - 5 degrees.

a principal middle level cloud type (cloud genus) in the form of a grayish (gray) or bluish cloud sheet or layer of striated, fibrous, or uniform appearance, totally or partly covering the sky; the layer has parts thin enough to reveal the position of the sun; halo phenomena do not usually occur.

any wind blowing up a steep incline or mountain; the opposite of katabatic wind.

in synoptic meteorology, a detailed study of the state of the atmosphere over a particular region based on the actual observations.

submerged ice which is attached to the bottom.

an instrument which measures wind speed or wind speed and direction; a cup anemometer measures the wind speed from the speed of rotation of a windmill which consist of 3 or 4 hemispherical or conical cups, each fixed to the ends of horizontal arms attached to a vertical axis; a byram anemometer is a variety of the cup anemometer; a counting anemometer has cups or a fan whose rotation is transmitted to a technical counter which integrates directly the air movement speed; a hand anemometer is small portable anemometer held at arm's length by an observer making a wind speed measurement; a pressure tube anemometer (dines anemometer) is an instrument which derives wind speed from measurements of the dynamic wind pressures - wind blowing into a tube develops a pressure greater than the static pressure, while wind blowing across a tube develops a pressure less than the static, this pressure difference is proportional to the square of the wind speed.

a Russian anemograph (recording anemometer) which is equipped with a device to record the wind direction in addition to wind speed.

a Russian anemometer combined with a vane to determine the wind direction.

an instrument for measuring atmospheric pressure; it is constructed on the following principles: an aneroid capsule (vidie capsule, which is a thin, disk-shaped box or capsule, usually metallic) is partially evacuated of gas, and is restrained from collapsing by an external or internal spring; the deflection of the spring will be nearly proportional to the difference between the internal and external pressures; magnification of the spring deflection is obtained both by connecting capsules in series and by mechanical linkages.

deviation of a meteorological quantity value in a given region from the normal (mean) value for the same period.

the line of latitude 66° 34′ S (often taken as 66.5° S); along this line the sun does not set on the day of the summer solstice, and does not rise on the day of the winter solstice.

also known as the antarctic convergence; the southern front of the antarctic circumpolar current that separates the antarctic zone in the south from the polar frontal zone in the north; taken by many to delineate the actual northern boundary of the antarctic zone; characterized by sea surface temperatures near 5°–6° C and a salinity minimum of 33.8–34.0 psu produced by high rainfall.

the region between the antarctic circle (66° 34′ S) and the South Pole; climatically, the limit of the zone may be set at about 60° S, poleward of which the prevailing westerly winds give place to easterly or variable winds; over most of this region the average temperature does not rise above 0°C (32°F) even in summer.

the prevention of ice accumulation of aircraft, ships and other objects; the most common measures are heating or applying a dressing by brush or spray to weaken adhesion and facilitate removal.

an ice wedge that grows progressively downwards into a receding slope, in a direction normal (perpendicular) to the surface.

area of increased atmospheric pressure relative to surrounding pressure field in the atmosphere; it is outlined by closed isobars on a synoptic surface chart, and by closed contours on a constant-pressure chart; this term is used interchangeably with high.

area of increased atmospheric pressure relative to surrounding pressure field in the atmosphere; outlined by closed isobars on a synoptic surface chart, and by closed contours on a constant-pressure chart; used interchangeably with high..

system of air movements (atmospheric circulation) associated with an anticyclone, which is clockwise in the northern hemisphere and counter-clockwise in the southern hemisphere.

the amount of heat required to raise the temperature of a unit mass of frozen ground by one degree.

the cumulative number of degree-days below 0 degrees Celsius for a given time period, calculated from the mean monthly temperatures for a specific station without making corrections for positive degree-days in spring and fall.

the cumulative number of degree-days above 0 degrees Celsius for a given time period, calculated from the mean monthly temperatures for a specific station without making corrections for negative degree-days in spring and fall.

(from Greek arktikos which means northern) northern polar region of the earth which includes almost the whole area of the Arctic Ocean and adjacent areas of Eurasian and North American continents.

mass of very cold air in the arctic regions which invades lower latitudes at irregular intervals.

the line of latitude 66 degrees 34 minutes N (often taken as 66.5 degrees N); along this line, the sun does not set on the day of the summer solstice, and does not rise on the day of the winter solstice.

(1) the semi-permanent, semi-continuous front between the deep, cold arctic air and the shallower, basically less cold polar air of northern latitudes (2) south boundary of the arctic air mass.

haze in arctic regions which reduces horizontal and slant visibility and which may extend to a height of about 10 km; it appears blue-grey when viewed away from the sun, and reddish-brown toward it.

a weak high which appears over the arctic basin during late spring, summer and early autumn; one of the centers of action in the atmosphere.

a mist of ice crystals; a very light ice fog.

an atmospheric circulation pattern in which the atmospheric pressure over the polar regions varies in opposition with that over middle latitudes (about 45 degrees N) on time scales ranging from weeks to decades; the oscillation extends through the depth of the troposphere, and from January to March, it extends upward into the stratosphere where it modulates in the strength of the westerly vortex that encircles the arctic polar cap region; the north atlantic oscillation and arctic oscillation are different ways of describing the same phenomenon.

evaporation (steam) fog produced above a surface of open water within arctic ice when the air is stable and relatively cold.

the northern limit of tree growth; the sinuous boundary between tundra and boreal forest; taken by many to delineate the actual southern boundary of the arctic zone.

(1) geographically, the area north of the arctic circle (66° 34′ N) (2) (same as tundra) biogeographically, the area extending northward from the arctic tree line; also used for the level above the timber line in mountains.

sharp, narrow ridge formed as a result of glacial erosion from both sides.

the process of inducing or maintaining a frozen condition in earth materials by artificial means.

the envelope of air surrounding the earth and bound to it more or less permanently by virtue of the earth's gravitational attraction; the system whose chemical properties, dynamic motions, and physical processes constitute the subject matter of meteorology.

the large-scale movement of air, and the means by which heat is distributed on the surface of the Earth; may vary from year to year.

as commonly used in weather observing practice, an observable occurrence of particular physical significance within the atmosphere; from the viewpoint of weather observations, the atmospheric phenomena include all hydrometeors (precipitation types and fogs), blowing snow, thunderstorms, tornadoes, waterspouts, and others.

pressure (force per unit area) exerted by the atmosphere on any surface by virtue of its weight; it is equivalent to the weight of a vertical column of air extending above a surface of unit area to the outer limit of the atmosphere.

longwave (infrared) radiation emitted by or being propagated through the atmosphere.

luminous phenomena, in the form of arcs, bands, draperies, or curtains in the high atmosphere over high latitudes; auroras are related to magnetic storms and the influx of charged particles from the sun, the phenomena are called aurora borealis in the northern hemisphere and aurora australis in the southern hemisphere.

mass of snow which becomes detached and slides down a slope, often acquiring great bulk by fresh addition as it descends.

arithmetic mean (m) of a number (n) of values (x1, x2, ... xn), defined by the equation: m = sxi/n; annual average value is calculated from 12 monthly means; daily average (or mean) value is calculated from 24 hourly readings of a meteorological element, or often from the average of the daily maximum and minimum values (for example, of temperature); monthly average is usually calculated as the average of the daily average values.

the semipermanent subtropical high over the North Atlantic Ocean, especially when it is located over the eastern part of the ocean; the same high over the western part of the Atlantic is called the Bermuda high; on mean charts of sea level pressure, this high is one of the primary centers of action in northern latitudes.

alternate bands of light and dark on a glacier; usually found below steep narrow icefalls and thought to be the result of different flow and ablation rates between summer and winter.

a distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form subhorizontal layers.

a barometer that records barometric pressure over time (days or weeks).

an instrument for measuring atmospheric pressure; two types of barometers are commonly used in meteorology: the mercury barometer and the aneroid barometer.

areas of discontinuous vegetation cover in the polar semi-desert of the high arctic.

a layer of unfrozen ground that is perennially cryotic (t < 0 degrees Celsius), forming the basal portion of the permafrost.

the cryostructure of a frozen deposit of boulders that is saturated with ice.

the sliding of a glacier over bedrock.

the cryostructure of a frozen layered deposit of gravel and boulders that is saturated with ice.

a stream characterized by narrow reaches linking pools or small lakes.

an ocean and ice circulation pattern in the Beaufort Sea, north of Alaska. This gyre moves in a clockwise direction, fed by an average high-pressure system that fosters anti-cyclonic winds. Ice that forms in or drifts into the Beaufort Gyre has historically remained in the Arctic ice system for years, accumulating snow and thickening each winter. Beginning in the late 1990s, the ice began melting away while in the southern parts of the gyre, before completing the circulation.

hard-packed rock lying below the Earth’s surface; lies in beds or layers; can be variable across geographic space; above bedrock is a layer of broken, weathered rock.

a long area of pack ice from a few km to more than 100 kilometers in width.

crevasse that separates flowing ice from stagnant ice at the head of a glacier.

large chunk of glacier ice (a very small iceberg) floating in the sea; bergy bits are usually less than 5 meters (15 feet) in size and are generally spawned from disintegrating icebergs.

the semipermanent subtropical high over the North Atlantic Ocean, especially when it is located over the western part of the ocean; the same high over the eastern part of the Atlantic is called the Azores high; on mean charts of sea level pressure, this high is one of the primary centers of action in northern latitudes.

situation of a vessel surrounded by ice and unable to move.

an extensive crescent-shaped indentation in the ice edge, formed either by wind or current.

a lead closed off on all sides within the ice pack.

winds of at least 35 miles per hour along with considerable falling and/or blowing snow reducing visibility to less than one-quarter mile for a period of at least three hours (extremely cold temperatures are often associated with dangerous blizzard conditions, but are not a formal part of the modern definition).

a surficial layer of angular shattered rocks formed in either modern or pleistocene periglacial environments.

opening through a snow bridge into a crevasse or system of crevasses which are otherwise sealed by snow bridges; a snowdrift usuallly forms on the lee side.

an ensemble of snow particles raised by the wind to moderate or great heights above the ground; the horizontal visibility at eye level is generally very poor.

a cold wind blowing down an incline; a kind of katabatic wind.

the forested region that adjoins the tundra along the arctic tree line, which has two main divisions: its northern portion is a belt of taiga or boreal woodland, while its southern portion is a belt of true forest, mainly conifers but with some hardwoods; on its southern boundary the boreal forest passes into “mixed forest” or “parkland,” prairie, or steppe, depending on the rainfall.

icebergs that originate from near the bottom of a glacier; the color is usually black from trapped rock material or dark blue because of old, coarse, bubble-free ice; they sit low in the water due to the weight of the embedded rocks.

temperature measured at the base of the snow cover during mid- to late-winter (February/March).

glacier that has one or more tributary glaciers that flow into it; distinguished from a simple valley glacier that has only a single tributary glacier.

accumulation of floating ice made up of fragments not more than 2 meters (6.6 feet) across, the wreckage of other forms of ice.

small droplets of highly saline water that form in pockets between ice crystals, as sea ice forms and expels salt into the underlying ocean water.

method to predict the presence or absence of permafrost in a mountain area, using measurements of the bottom temperature of snow cover mid- to late-winter.

smooth hills of ice that form on the bottom of sea ice from eroding keels, particularly during the summer melt.

a buoy, either fixed or floating, which carries instruments for sensing various meteorological elements and for transmitting the data by radio.

ice formed or deposited on the ground surface and later covered by sediments.

Meterological law which states that if you are standing with your back to the wind in the Northern Hemisphere, low pressure will be on your left, and high pressure will be on your right. Ballot was a 19th century Dutch climatalogist.

break off from a larger ice shelf or ice sheet into the water.

process by which ice breaks off a glacier's terminus; usually the term is reserved for tidewater glaciers or glaciers that end in lakes, but it can refer to ice that falls from hanging glaciers.

glacier that loses material by calving, usually a glacier that terminates in sea, lake, or river water.

A reservoir of carbon dioxide that is increasing in size.

a semipermanent mass of firn formed by drifted snow behind obstructions or in the ground; also called a snowdrift glacier or a drift glacier.

ice formed in a closed or open cave.

striations or marks left on the surface of exposed bedrock caused by the advance and retreat of glacier ice.

a warm wind blowing down an incline; a kind of katabatic wind.

the large-scale cyclonic circulation in the middle and upper troposphere centered generally in the polar region; also called polar vortex.

bowl shape or amphitheater usually sculpted out of the mountain terrain by a cirque glacier.

glacier that resides in basins or amphitheaters near ridge crests; most cirque glaciers have a characteristic circular shape, with their width as wide or wider than their length.

a principal high-level cloud type (cloud genus), appearing as a thin, white patch or layer of cloud without shading, composed of very small elements in the form of grains, ripples, etc., merged or separated, and more or less regularly arranged; most of the elements have an apparent width of less than 1 degree.

a principal high-level cloud type (cloud genus), appearing as a transparent, whitish cloud veil of fibrous (hair-like) or smooth appearance, totally or partially covering the sky, and often producing halo phenomena, either partial or complete.

a principal high-level cloud type (cloud genus), appearing as detached clouds in the form of white, delicate filaments or white or mostly white patches or narrow bands; these clouds have a fibrous (hair-like) appearance, or a silky sheen, or both; because cirrus elements are too narrow, they do not produce a complete circular halo.

sky with a total cloud cover of less than one okta (or one-tenth in the united states).

synthesis of weather conditions in a given area, characterized by long-term statistics (mean values, variances, probabilities of extreme values, etc.) of the meteorological elements in that area; polar climate (arctic climate) is generally the climate of a geographical polar region, most commonly taken to be a climate which is too cold to support the growth of trees.

a study dealing with variations in climate on many different time scales from decades to millions of years, and the possible causes of such variations; (1) in the most general sense, the term climate change encompasses all forms of climatic inconstancy (that is, any differences between long-term statistics of the meteorological elements calculated for different periods but relating to the same area) regardless of their statistical nature or physical causes; climate change may result from such factors as changes in solar activity, long-period changes in the earth's orbital elements (eccentricity, obliquity of the ecliptic, precession of equinoxes), natural internal processes of the climate system, or anthropogenic forcing (for example, increasing atmospheric concentrations of carbon dioxide and other greenhouse gases) (2) the term climate change is often used in a more restricted sense, to denote a significant change (such as a change having important economic, environmental and social effects) in the mean values of a meteorological element (in particular temperature or amount of precipitation) in the course of a certain period of time, where the means are taken over periods of the order of a decade or longer.

representation of the climate system based on the mathematical equations governing the behavior of the various components of the system and including treatment of key physical processes and interactions, cast in a form suitable for numerical approximation with computers.

(1) in the most general sense, the term climate variability denotes the inherent characteristic of climate which manifests itself in changes with time; the degree of climate variability can be described by the differences between long-term statistics of meteorological elements calculated for different periods, (in this sense, the measure of climate variability is the same as the measure of climate change) (2) the term climate variability is often used to denote deviations of climate statistics over a given period of time (such as a specific month, season or year) from the long-term climate statistics relating to the corresponding calendar period; (in this sense, climate variability is measured by those deviations, which are usually termed anomalies).

atlas composed mainly of climatological charts; it represents especially the monthly and annual distributions of the principal climatic elements of a specific region for a relatively long period.

the scientific study of climate; the aspect of meteorology which studies processes of climate formation, distribution of climates over the globe, analysis of the causes of differences of climate (physical climatology), and the application of climatic data to the solution of specific design or operational problems (applied climatology); climatology may be further subdivided according to purpose or point of view: agricultural climatology, air-mass climatology, aviation climatology, bioclimatology, dynamic climatology, medical climatology, macroclimatology, mesoclimatology, microclimatology, paleoclimatology, synoptic climatology, etc..

ice formed in a closed space, cavity or cave in permafrost.

composed of close ice that is mostly in contact; ice cover 7/10ths to 9/10ths.

a layer or body of unfrozen ground occupying a depression in the permafrost table below a lake or river.

freezing that occurs under conditions that preclude the gain or loss of any water by the system.

a pingo formed by doming of frozen ground due to freezing of injected water supplied by expulsion of pore water during permafrost aggradation in the closed talik under a former water body.

a hydrometeor consisting of a visible aggregate of minute particles of liquid water or ice, or both, suspended in the free air and usually not touching the earth's surface; it may also include larger particles of liquid water or ice (precipitation particles) and non-aqueous liquid or solid particles such as those present in fumes, smoke and dust (aerosols); cloudiness is the same as cloud cover; but usually it is used in a very general sense.

that portion of the sky cover which is attributed to clouds; the unit of measurement is the okta or tenths (meaning one-eighth or one-tenth) of the sky dome as seen by the observer.

decrease in volume per unit volume of a substance resulting from a unit increase in pressure, under isothermic conditions.

any non-occluded front that moves in such a way so that colder air replaces warmer air; the leading edge of a relatively cold air mass.

glacier in which most of the ice is below the pressure melting point; nonetheless, the glacier's surface may be susceptible to melt due to incoming solar radiation, and the ice at the rock/ice interface may be warmed as a result of the natural (geothermal) heat from the earth's surface.

at a given level in the atmosphere, any low that is generally characterized by colder air near its center than around its periphery; the opposite of a warm low.

the location that has the lowest annual mean temperature in its hemisphere.

that portion of a peatland where the whole or part of a palsa or peat plateau has thawed and collapsed to the level of the surrounding peatland.

a wedge showing evidence of both primary and secondary filling.

flow that occurs when glacier motion is decelerating down-slope.

the physical process by which a vapor becomes a liquid or solid; the opposite of evaporation; in meteorological usage, this term is applied only to transformation from vapor to liquid; any process in which a solid forms directly from its vapor is termed sublimation, as is the reverse process.

the transport of energy entirely resulting from the random motions of individual molecules, and not from any concerted group movement; occurs in response to temperature gradients; contrasts with convection, in which energy is transported by molecules moving together in coherent groups.

an advanced form of new ice that forms as a stable sheet with a smooth bottom surface.

a distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which coarser soil particles form compound arrangements.

pack ice in which the floes are frozen together; ice cover 10/10ths.

special design and construction procedures required when engineering works are undertaken in permafrost areas.

snow metamorphism that adds molecules to sharpen the comers and edges of an ice crystal.

geographic area in which permafrost occurs everywhere beneath the exposed land surface with the exception of widely scattered sites, such as newly deposited unconsolidated sediments that have just been exposed to the freezing climate; mean annual soil surface temperatures are typically below -5 degrees Celsius (23 degrees Fahrenheit).

the major subdivision of a permafrost region in which permafrost occurs everywhere beneath the exposed land surface with the exception of widely scattered sites.

the transport of energy resulting from the concerted movement of molecules in coherent groups; contrasts with conduction in which energy is transported by the random motions of molecules; atmospheric convection is nearly always turbulent and results in the vertical transport and mixing of atmospheric properties.

cumuliform cloud which forms in the atmosphere as a result of convection; such clouds are also called clouds of vertical development, a cloud that has its base in the low height range but extends upward into the middle or high altitudes.

apparent force, due to the rotation of the earth, which acts normal to, and to the right of the velocity of a moving particle in the northern hemisphere, the movement of the particle being considered relative to that of the earth.

an overhanging accumulation of ice and wind-blown snow, characteristically found on the edge of a ridge or cliff face.

any fracture or rift in floating ice not sufficiently wide to be described as a lead.

a way that snow or ice can move by deforming its internal structure.

the slow deformation (or time-dependent shear strain) that results from long-term application of a stress too small to produce failure in the frozen material.

the failure strength of a material at a given strain rate or after a given period under deviatoric stress.

open fissure in the glacier surface.

a kind of hoarfrost; ice crystals that develop by sublimation in glacial crevasses and in other cavities with cooled space and calm, still conditions under which water vapor can accumulate; physical origin is similar to depth hoar.

a hard snow surface lying upon a softer layer; crust may be formed by sun, rain or wind, and is described as breakable crust or unbreakable crust, depending upon whether it wil break under the weight of a turning skier.

the cryostructure of a frozen deposit of angular blocks that are coated with ice, whereas large spaces between the blocks are not filled with ice.

the boundary between cryotic and noncryotic ground as indicated by the position of the 0 degrees Celsius isotherm in the ground.

the combination of thermophysical, physico-chemical and physico-mechanical processes occurring in freezing, frozen and thawing earth materials.

a layer of ground which, because of its frozen state, has a low enough permeability to act as a confining bed for an aquifer.

the distinct soil micromorphology resulting from the effects of freezing and thawing processes.

in international materials science, this term refers to temperatures generally below -50 degrees Celsius, but usually to temperatures within a few degrees of absolute zero (-273 degrees Celsius).

the study of the genesis, structure and lithology of frozen earth materials.

the study of soils at temperatures below 0 degrees Celsius, with particular reference to soils subject to intensive frost action, and to soils overlying permafrost.

a layer of unfrozen ground that is perennially cryotic (forming part of the permafrost), in which freezing is prevented by freezing-point depression due to the dissolved-solids content of the pore water.

the process through which cryoplanation terraces form.

a step-like or table-like bench cut in bedrock in cold climate regions.

soil formed in either mineral or organic materials having permafrost either within 1 meter (3.3 feet) below the surface or, if the soil is strongly cryoturbated, within 2 meters (6.6 feet) below the surface, and having a mean annual ground temperature below 0 degrees Celsius.

one of the earth's spheres of irregular form existing in the zone of interaction of the atmosphere, hydrosphere and lithosphere, distinguished by negative or zero temperature and the presence of water in the solid or super-cooled state; the term refers collectively to the portions of the earth where water is in solid form, including snow cover, floating ice, glaciers, ice caps, ice sheets, seasonally frozen ground and perennially frozen ground (permafrost).

the structural characteristics of frozen earth materials.

a suction developed in freezing or partially frozen fine-grained materials as a result of temperature-dependent differences in unfrozen water content.

the textural characteristics of frozen, fine-grained organic and mineral earth materials cemented together with ice.

soil or rock at temperatures of 0 degrees Celsius or lower.

a body of earth material moved or disturbed by frost action.

(1) (singular) a collective term used to describe all soil movements due to frost action (2) (plural) irregular structures formed in earth materials by deep frost penetration and frost action processes, and characterized by folded, broken and dislocated beds and lenses of unconsolidated deposits, included organic horizons and even bedrock.

like cumulus; generally descriptive of all clouds; vertical development in the form of rising mounds, domes or towers; driven by thermal convection and have vertical velocities greater than 1 meter (3.3 feet) per second.

a principal cloud type (cloud genus) of vertical development, exceptionally dense and vertically developed clouds, occurring either as isolated clouds or as a line or wall of clouds with separated upper portions; these clouds appear as mountains or huge towers, at least a part of the upper portions of which are usually smooth, fibrous, or striated, and almost flattened; this part often spreads out in the form of an anvil (incus) or vast plume; under the base of cumulonimbus, which is very dark, there frequently exist virga, precipitation, and low, ragged clouds, either merged with it or not; its precipitation is often heavy and always of a showery nature.

a principal low-level cloud type (cloud genus) in the form of individual, detached elements which are generally dense and possess sharp non-fibrous outlines; these elements develop vertically, appearing as rising mounds, domes, or towers, the upper parts of which often resembles a cauliflower; the sunlit parts of these clouds are mostly brilliant white; their bases are relatively dark and nearly horizontal; near the horizon the vertical development of cumulus often causes the individual clouds to appear merged; if precipitation occurs, it is usually of a showery nature.

process of initiation or intensification of a cyclonic circulation in the atmosphere; the opposite to cyclolysis.

process of weakening or terminating of a cyclonic circulation in the atmosphere; the opposite of cyclogenesis.

area in the atmosphere in which the pressures are lower than those of the surrounding region at the same level; it is represented on a synoptic chart by a system of isobars at a specified altitude level (or a system of contours at a specified pressure level) which enclose relatively low values of pressure (or altitude); a cyclone begins when a wave (young) cyclone forms and moves along a front; a mature cyclone has well-developed warm sectors and both cold and warm fronts; an occluded cyclone is that within which there has developed an occluded front.

atmospheric circulation associated with a cyclone (depression, low pressure area); it is counterclockwise in the northern hemisphere and clockwise in the southern hemisphere.

the spatial displacement of a center of low pressure caused by the local redistribution of mass in the atmosphere; the trajectory of the center is often altered by heating or cooling on the air column, which can result from thermal fluxes at the surface or latent heat transformations associated with cloud formation and precipitation; these processes change the temperature distribution in the air column, resulting in density changes which modify the surface pressures.

the removal of ice accumulation on aircraft, ships and other objects by mechanical, thermal or chemical devices.

any part of a glacier which has ceased to flow; dead ice is usually covered with moraine.

a sudden and destructive variety of landslide, in which loose material on a slope, with more than 50% of particles larger than sand size, is mobilized by saturation and flows down a channel or canyon.

the ability of a material to change its shape or size under the influence of an external or internal agency, such as stress, temperature, or pore pressure.

(1) the total degree of saturation of frozen soil is the ratio of the volume of ice and unfrozen water in the soil pores to the volume of the pores (2) the degree of saturation of frozen soil by ice is the ratio of the volume of ice in the soil pores to the volume of the pores.

a derived unit of measurement used to express the departure of the mean temperature for a day from a given reference (or base) temperature.

the failure strength of a material at a given strain rate or after a given period under deviatoric stress.

hexagonal ice crystals with complex and often fernlike branches.

the mass of a unit volume of frozen soil or rock.

in meteorology, an area of low pressure (i.e. a low); usually applies to a particular stage in the development of a cyclone.

a kind of hoarfrost; ice crystals that develop by sublimation within a layer of dry snow; characterized by rapid recrystallization, usually caused by large temperature gradients; similar in physical origin to crevasse hoar; crystals are faceted, rather than rounded.

the maximum thickness of the seasonally frozen layer.

vertical interval between the top surface of a snow layer and the ground beneath; the layer is assumed to be evenly spread over the ground which it covers.

the minimum distance between the ground surface and frozen ground at any time during the thawing season in an area subject to seasonal freezing and thawing.

the distance from the ground surface downward to the level beneath which there is practically no annual fluctuation in ground temperature.

crack or fissure developed in fine-grained soil material as a result of shrinkage during drying.

closed, multi-sided, patterned ground feature formed by desiccation cracks in fine-grained soil material, usually less than 2 meters (6.6 feet) in diameter.

(1) (North American usage) the mean of the three largest depths of seasonal frost penetration measured during the past thirty years, or the largest depth of seasonal frost penetration beneath a snow-free soil surface measured during the past ten years (2) (Russian usage) the mean of the depths of seasonal frost penetration measured during at least the last ten years with the ground surface free of snow and the groundwater level below the depth of seasonal frost penetration.

the cumulative number of degree-days below 0 degrees Celsius, calculated by taking the average of the seasonal freezing indices for the three coldest winters in the most recent 30 years of record.

the cumulative number of degree-days above 0 degrees Celsius, calculated by taking the average of the seasonal thawing indices for the three warmest summers in the most recent 30 years of record.

snow metamorphism that rounds the comers and edges of an ice crystal.

a slope failure in which the thawed or thawing portion of the active layer detaches from the underlying frozen material.

the temperature to which a given parcel of air must be cooled at constant pressure and constant water-vapor content in order for saturation to occur; when this temperature is below 0 degrees Celsius, it is called the frost point.

a type of precipitation composed of slowly falling, very small, unbranched crystals of ice which often seem to float in the air; it may fall from a high cloud or from a cloudless sky, it usually occurs under frosty weather conditions (under very low air temperatures).

measure of the ability of the soil to store electrical energy in the presence of an electrostatic field.

a tensile fracture in a frozen material due to surface extension caused by doming.

ice that forms in dilation cracks.

either of the two points on the earth's surface at which magnetic meridians converge; the horizontal component of the magnetic field of the earth becomes zero at this point; also called the magnetic pole.

a cone-shaped formation of ice that is covered by dirt; a dirt cone is caused by a differential pattern of ablation between the dirt covered surface and bare ice.

ice that contains sediments stirred up and tangled in the ice as it grows.

permafrost occurring in some areas beneath the exposed land surface throughout a geographic region where other areas are free of permafrost.

the major subdivision of a permafrost region in which permafrost occurs in some areas beneath the exposed land surface, whereas other areas are free of permafrost.

permafrost that is not in thermal equilibrium with the existing mean annual surface or sea-bottom temperature and the geothermal heat flux.

preferred path for meltwater to flow from the surface through a snow cover.

a semipermanent mass of firn formed by drifted snow behind obstructions or in the ground; also called a catchment glacier or a snowdrift glacier.

ice that moves from winds, currents, or other forces.

displacement of a sea ice field from its place of origin under the effect of ocean currents and winds.

floating (or drifting on ice) ocean buoy equipped with meteorological and/or oceanographic sensing instruments linked to transmitting equipment for sending the observed data to collecting centers.

snow raised from the surface of the earth by the wind to a height of less than 1.5 to 2.0 meters (5 to 6.6 feet) above the surface; it dose not restrict horizontal visibility at 2 meters (6.6 feet) or more above the surface.

research stations on the floes of the arctic ocean.

very small, uniformly distributed water drops that appear to float while following air currents; unlike fog droplets, drizzle falls to the ground.

remnant elongated hills formed by historical glacial action; it is not clear exactly how they are formed and why they form only in some glaciated regions.

trees leaning in random directions caused by melting permafrost.

the mass of a unit volume of dried material (e.g. soil).

frozen ground with a very low total water content consisting almost completely of interfacial water, and not cemented by ice.

permafrost containing neither free water nor ice.

a mound or layer of moraine formed along the edge of a glacier by rock that falls off the ice; sometimes called a ground moraine.

the ratio of stress to strain for a material under dynamic loading conditions.

the absolute value of the ratio between the linear strain changes, perpendicular to and in the direction of a given uniaxial stress change, respectively, under dynamic loading conditions.

a hummock having a core of silty and clayey mineral soil which may show evidence of cryoturbation.

the total infrared radiation emitted from the earth's surface; to be carefully distinguished from effective terrestrial radiation, atmospheric radiation, and insolation.

process by which warm water erodes iceberg above the waterline

the difference between the outgoing infrared (longwave) terrestrial radiation of the earth's surface and the downward infrared counter-radiation from the atmosphere.

the inverse of electrical resistivity.

the dielectric constant (or relative permitivity), electrical conductivity and electrical resistivity are the major electrical properties governing the flow of electric current through frozen ground.

the property of a material that determines the electrical current flowing through a centimetre cube of the material when an electrical potential is applied to opposite faces of the cube.

an oscillation of the electric or magnetic field associated with the propagation of energy; characterized by their wavelengths and amplitude; propagate at the speed of light.

the amount of electromagnetic energy (primarily at wavelengths longer than 1.0 micrometer) that an object emits; for example, the earth emits longwave radiation primarily in the infrared part of the electromagnetic spectrum, but also in longer microwave wavelengths; the emissivity of an object varies as the fourth power of its absolute temperature.

an arch-shaped ridge of moraine found near the end of a glacier.

ground ice developed in epigenetic permafrost, or in previously formed syngenetic permafrost.

an ice wedge developed in epigenetic permafrost, or in previously formed syngenetic permafrost.

permafrost that formed through lowering of the permafrost base in previously deposited sediment or other earth material.

the line of latitude 0°, which is equidistant from the poles, and which separates the Northern Hemisphere from the Southern Hemisphere.

snow metamorphism that occurs under relatively consistent temperature conditions.

boundary between the accumulation area and ablation area where the mass balance is zero.

snow metamorphism that occurs when there are large differences in convex and concave portions of a crystal.

permafrost that is in thermal equilibrium with the existing mean annual surface or sea-bottom temperature and with the geothermal heat flux.

zone of a glacier in which the amount of precipitation that falls is equal to the amount that melts the following summer.

either of the two points of intersection of the sun's apparent annual path and the plane of the earth's equator; in the northern hemisphere the spring (vernal) equinox falls on or about 21 March, and the autumnal equinox on or about 22 September.

the difference between a measured value of a quantity and its true value; different types of errors are inherent to observations.

a sinuous ridge of sedimentary material (typically gravel or sand) deposited by streams that cut channels under or through the glacier ice.

the physical process by which a liquid or solid substance is transformed to the gaseous state; the opposite of condensation; in meteorology, evaporation usually is restricted in use to the change of water from liquid to gas, while sublimation is used to the change from solid to gas as well as from gas to solid.

fog formed as a result of evaporation of water that is warmer than the air.

the volume of ice in the ground which exceeds the total pore volume that the ground would have under natural unfrozen conditions.

when glacier motion is accelerating down-slope.

(1) (North American usage) permafrost underlying 65 - 90% of the area of exposed land surface (2) (Russian usage) permafrost underlying 70 - 80% of the area of exposed land surface.

soil micromorphology.

a cold wind blowing down an incline; a kind of katabatic wind.

bands of light and dark on a glacier that were formed by rock avalanching.

ice that is anchored to the shore or ocean bottom, typically over shallow ocean shelves at continental margins; fast ice is defined by the fact that it does not move with the winds or currents.

a region of space at each point of which a given physical or mathematical quantity has some definite value; for example, a gravitational field, magnetic field, or electric field; and, in meteorology, a pressure field, temperature field, etc; if the quantity specified at each point is a vector quantity, the field is said to be a vector field.

a process by which currents or winds push around thin ice so they slide over each other.

rounded, well-bonded snow that is older than one year; firn has a density greater than 550 kilograms per cubic-meter (35 pounds per cubic-foot); called névé during the first year.

the minimum elevation of firn lying on a glacier surface; each year's firn line marks a glacier's annual equilibrium line; also called firn line.

the minimum elevation of firn lying on a glacier surface; each year's firn line marks a glacier's annual equilibrium line; also called firn limit.

the height of meltwater within saturated firn that is trapped over ice in a glacier.

a thin sheet of ice formed on the glacier surface by rapid refreezing of solar-heated snow or firn, usually at high elevations during spring.

floating ice of no more than one year's growth developing from young ice; thickness from 0.3 to 2 meters (1 to 6.6 feet); characteristically level where undisturbed by pressure, but where ridges occur, they are rough and sharply angular.

glacial troughs that fill with sea water.

a navigable passage between pack ice and fast ice.

any form of ice found floating in water.

separate patch of floating ice or flat sheet of unbroken pack ice, greater than 20 meters (22 yards) across.

ice that is pushed into the underlying ocean water by the weight of thick snow cover on its surface; the salty ocean water floods the snow cover and creates a salty, slushy layer; flooded sea ice is more common in the antarctic because of more snowfall and thinner sea ice than in the arctic.

a small percolation channel that is a beginning path for surface meltwater through snow or firn.

an iceberg that is grooved into a curtain-like pattern; thought to be carved by small meltwater streams.

a warm wind blowing down an incline; a kind of katabatic wind.

a hydrometeor consisting of a visible aggregate of minute water droplets (or ice crystals), suspended in the atmosphere near the earth's surface; according to international definition, fog reduces visibility below one kilometer, fog differs from cloud only in that the base of fog is at the earth's surface while clouds are above the surface; when composed of ice crystals, it is termed ice fog.

layering in glacier ice that has distinctive crystal sizes and/or bubbles; foliation is usually caused by stress and deformation that a glacier experiences as it flows over complex terrain, but can also originate as a sedimentary feature.

alternate bands of light and dark on a glacier; usually found below steep narrow icefalls and thought to be the result of different flow and ablation rates between summer and winter.

shallow, parallel grooves on the face of a large melting ice crystal.

structure used when the soil near the ground surface is not strong and the weight of the building must be carried by deeper soil layers.

a distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form discrete units that are densely packed.

a distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form discrete units that are coalescing.

a sea channel connecting the Arctic Ocean and the Nordic Seas, running between Greenland and Spitsbergen. Fram Strait is the passageway where most drifting sea ice exits the Arctic.

small needle-like ice crystals, typically 3 to 4 millimeters in diameter, suspended in water, that represent the first stages of sea ice growth; they merge under calm conditions to form thin sheets of ice on the surface, frazil crystals consist of nearly pure fresh water.

fine spicules or plates of ice in suspension in water.

free water is that portion of the pore water that is free to move between interconnected pores under the influence of gravity.

freezing of a material followed by thawing.

refreezing of thawed materials.

the changing of phase from water to ice in soil or rock.

a measure of how cold it has been and how long it has been cold; the cumulative fdd is usually calculated as a sum of average daily degrees below freezing for a specified time period (10 days, month, season, etc.).

drizzle, the drops of which freeze on impact with the ground or with objects on the earth's surface or with aircraft in flight.

the advancing boundary between frozen (or partially frozen) ground and unfrozen ground.

the cumulative number of degree-days below 0 degrees Celsius for a given time period.

(1) the temperature at which a pure liquid solidifies under atmospheric pressure (2) the temperature at which a ground material starts to freeze.

the positive pressure developed at ice-water interfaces in soil as it freezes.

rain, the drops of which freeze on impact with the ground or with objects on the earth's surface or with aircraft in flight.

the number of degrees by which the freezing point of an earth material is depressed below 0 degrees Celsius.

permafrost in which the soil particles are not held together by ice.

from the point of view of the submariner, an icey canopy containing many large ice skylights or other features which permit a submarine to surface; there must be more than ten such features per 37 kilometers (30 nautical miles) along the submarine's track.

in meteorology, generally, the interface or transition zone between two air masses of different density; since the temperature distribution is the most important regulator of the atmosphere density, a front almost invariably separates air masses of different temperature; when warmer air replaces the colder, it is a warm front, and vice-versa.

the condition which exists when the temperature near the earth's surface and earth-bound objects falls below freezing (0 degrees Celsius or 32 degrees Fahrenheit).

the process of alternate freezing and thawing of moisture in soil, rock and other materials, and the resulting effects on materials and on structures placed on, or in, the ground.

a seasonal frost mound produced through doming of seasonally frozen ground by a subsurface accumulation of water under elevated hydraulic potential during progressive freezing of the active layer.

a small mound of soil material, presumed to have been formed by frost action.

a more or less symmetrical zone of frozen ground formed around a buried chilled pipeline or beneath or around a structure maintained at temperatures below 0 degrees Celsius.

the net downslope displacement that occurs when a soil, during a freeze-thaw cycle, expands normal (perpendicular) to the ground surface and settles in a nearly vertical direction.

crystals of ice that form when water vapor becomes a solid (bypassing the liquid phase) and deposits itself on the sea ice surface; frost flowers roughen the surface and dramatically affect its electromagnetic signal.

the upward or outward movement of the ground surface (or objects on, or in, the ground) caused by the formation of ice in the soil.

the difference between the elevations of the ground surface before and after the occurrence of frost heave.

cumulative upward displacement of objects embedded in the ground, caused by frost action.

any mound-shaped landform produced by ground freezing combined with accumulation of ground ice due to groundwater movement or the migration of soil moisture.

the movement of the freezing front into the ground during freezing.

effects of frost action on earth materials and on structures placed in or on the ground.

the highest temperature at which atmospheric moisture will sublimate in the form of hoarfrost on a cooled surface; it is analogous to the dew point.

the mechanical disintegration of rock by the pressure of water freezing in pores and along grain boundaries.

fog-like clouds, due to the contact of cold air with relatively warm water, which appear over newly-formed leads, or leeward of the ice edge, and which may persist while new ice is forming.

the differential movement of soil particles of different sizes as a result of frost action.

the disintegration and break-up of soil or rock by the combined action of frost shattering, frost wedging and hydration shattering.

the mechanical disintegration, splitting or break-up of rock by the pressure of water freezing in cracks, crevices, pores, joints or bedding planes.

ground (soil or rock) in which little or no segregated ice forms during seasonal freezing.

soil in which little or no segregated ice forms during seasonal freezing.

ground (soil or rock) in which segregated ice will form (causing frost heave) under the required conditions of moisture supply and temperature.

soil in which segregated ice will form (causing frost heave) under the required conditions of moisture supply and temperature.

the zone in a freezing, frost-susceptible soil between the warmest isotherm at which ice exists in pores and the isotherm at which the warmest ice lens is growing.

soil or rock in which part or all of the pore water has turned into ice.

the phase transition of a substance passing from the solid to the liquid state, melting; in meteorology, fusion is understood to refer to the melting of ice, which, if the ice is pure and subjected to one standard atmosphere of pressure, takes place at the ice point of 0 degrees Celsius (32 degrees Fahrenheit).

a special form of solid clathrate compound in which crystal lattice cages or chambers, consisting of host molecules, enclose guest molecules.

in meteorology, general term for any device that measures strength of wind, pressure, and other parameters; the most widespread gauges on meteorology are balance snow gauge, barometer gauge, density-of-snow gauge, dew gauge, distance gauge, rain-and snow gauge, rain-intensity gauge, standard gauge, wind gauge, etc..

the slow downslope flow of unfrozen earth materials on a frozen substrate.

of the atmosphere; complete statistical description of atmospheric motions over the earth.

numerical representation of the atmosphere and its phenomena over the entire earth, using the equations of motion and including radiation, photochemistry, and the transfer of heat, water vapor, and momentum.

the study of earth materials having a temperature below 0 degrees Celsius.

the point of intersection of the Earth's surface with the axis of a simple magnetic dipole that best approximates the Earth's actual, more complex magnetic field; if the Earth's magnetic field were a perfect dipole then the field lines would be vertical at the geomagnetic poles, and they would therefore coincide with the magnetic poles: however, the dipole approximation is in fact far from perfect, so in reality the magnetic and geomagnetic poles lie some distance apart.

theoretical wind which results from the equilibrium between horizontal components of the pressure gradient force and the coriolis force (deviating force) above the friction layer; only these two forces (no frictional force) are supposed to act on the moving air; it blows parallel to straight isobars or contours.

the rate of temperature increase with depth in the subsurface.

the amount of heat moving steadily outward from the interior of the earth through a unit area in unit time.

fountain that develops when water from a conduit is forced up to the surface of a glacier; also called a negative mill.

when a mountain glacier's terminus extends farther downvalley than before; occurs when a glacier flows downvalley faster than the rate of ablation at its terminus.

a boulder swept from its place of origin by glacier advance or retreat and deposited elsewhere as the glacier melted; after glacial melt, the boulder might be stranded in a field or forest where no other rocks of its type or size exist.

grooves or gouges cut into the bedrock by gravel and rocks carried by glacial ice and meltwater; also called glacial striations.

when the position of a mountain glacier's terminus is farther upvalley than before; occurs when a glacier ablates more material at its terminus than it transports into that region.

grooves or gouges cut into the bedrock by gravel and rocks carried by glacial ice and meltwater; also called glacial grooves.

accumulations of unsorted, unstratified mixtures of clay, silt, sand, gravel, and boulders; the usual composition of a moraine.

a large u-shaped valley formed from a v-shaped valley by glacial erosion.

land covered in the past by any form of glacier is said to be glaciated.

a mass of ice that originates on land, usually having an area larger than one tenth of a square kilometer; many believe that a glacier must show some type of movement; others believe that a glacier can show evidence of past or present movement.

a cave of ice, usually underneath a glacier and formed by meltwater; cave entrances are often enlarged near a glacier terminus by warm winds; most common on stagnant portions of glaciers.

a phenomenon in which strong reflection of the sun on an icy surface causes a glacier to look like it is on fire.

a sudden outburst of water released by a glacier.

a fine powder of silt- and clay-sized particles that a glacier creates as its rock-laden ice scrapes over bedrock; usually flushed out in meltwater streams and causes water to look powdery gray; lakes and oceans that fill with glacier flour may develop a banded appearance; also called rock flour.

well-bonded ice crystals compacted from snow with a bulk density greater than 860 kilograms per cubic-meter (55 pounds per cubic-foot).

a nearly vertical channel in ice that is formed by flowing water; usually found after a relatively flat section of glacier in a region of transverse crevasses.

potholes formed at the bottom of glaciers through erosion caused by sand and gravel in melt-water; melt-water seeps through crevasses in the glaciers, sometimes forming whirpools; at the bottom of the glacier, the water is under very high pressure, leading to erosion of underlying rocks.

a glacier that is reconstructed or reconstituted out of other glacier material; usually formed by seracs falling from a hanging glacier, then re-adhering; also called reconstituted, reconstructed or regenerated glacier.

the lowest end of a glacier; also called glacier terminus or toe.

the bottom of the ice of a glacier.

a rock that resides on a pedestal of ice; formed by differential ablation between the rock-covered ice and surrounding bare ice.

the lowest end of a glacier; also called glacier snout or toe.

the lowest end of a glacier; also called glacier snout or terminus.

an extension of a glacier or ice stream projecting seaward, usually afloat.

u-shaped valleys transformed from v-shaped stream valleys due to erosion caused by passing glaciers.

a localized current of air occuring as a result of a glacier's melting processes; when the surface of glacial ice melts, the air above the glacier cools and becomes heavier than the surrounding air and flows down the glacial valley; glacier wind can also be wind that flows out of ice caves; a kind of katabatic wind.

a very small glacier.

land overlaid at present by a glacier is said to be covered; the alternative term glacierized has not found general favour.

a coating of ice, generally clear and smooth but usually containing some air pockets, formed on exposed objects by freezing of a film of super-cooled water deposited by rain, drizzle, fog, or possibly condensed from super-cooled water vapor; glaze is denser, harder and more transparent, than either rime or hoarfrost.

global network of observational stations which is the coordinated system of methods, techniques and facilities for making observations on a world-wide scale in the framework of the World Weather Watch, a World Meteorological Organization program.

the coordinated global system of telecommunication facilities and arrangements for the rapid collection, exchange and distribution of observational data in the framework of the World Weather Watch, a World Meteorological Organization program.

the same as geostrophic wind, but blowing parallel to curved isobars or contours; the curved airflow pattern around a pressure center results from a balance among pressure-gradient force, coriolis force, and centrifugal force.

a distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form discrete loosely packed units.

a distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form more or less discrete loosely packed units.

snowflakes that become rounded pellets due to riming; typical sizes are 2 to 5 millimeters in diameter (0.1 to 0.2 inch); graupel is sometimes mistaken for hail.

the ratio of the mass of the water and ice in a sample to the dry mass of the sample, commonly expressed as a percentage.

a wave disturbance in which buoyancy (or reduced gravity) acts as a restoring force on parcels displaced from hydrostatic equilibrium; there is a direct oscillatory conversion between potential and kinetic energy in the wave motion.

a cold wind blowing down an incline; a kind of katabatic wind.

a very thin, soupy layer of frazil crystals clumped together, which makes the ocean surface resemble an oil slick.

the anticyclone that appears to overlie Greenland; analogous to the antarctic anticyclone.

a category of young ice 15 to 30 centimeters (6 to 12 inches) thick, named for its color.

a finite collection of points to which the meteorological variables used in a numerical model, or interpolated from observations, apply; a field of such regular values (points) is termed gridded field.

a general term referring to all types of ice contained in freezing and frozen ground.

continuous layer of till near the edge or underneath a steadily retreating glacier.

an iceberg less than 2 meters (6.6 feet) across that floats with less than 1 meter (3.3 feet) showing above water; smaller than a bergy bit.

precipitation of small balls or pieces of ice (hailstones) with a diameter ranging from 5 to 50 millimeters (0.2 to 2.0 inches), or sometimes bigger, falling either separately or agglomerated into irregular lumps; when the diameter is less than about 5 millimeters (0.2 inch), the balls are called ice pellets.

group of optical phenomena, in the form of rings, arcs, pillars or bright spots around the sun or moon, produced by the refraction or reflection of light by ice crystals suspended in the atmosphere (cirrus clouds, diamond dust, etc.).

a glacier that terminates at or near the top of a cliff.

a valley formed by a small glacier that has a valley bottom relatively higher than nearby valleys formed by larger glaciers.

frozen ground (soil or rock) which is firmly cemented by ice.

fine dust or salt particles dispersed through a portion of the atmosphere; the particles are so small that they cannot be felt or individually seen with the naked eye, but they diminish horizontal visibility and give the atmosphere a characteristic opalescent appearance that subdues all colors; a type of lithometeor.

a steep cliff, usually the uppermost part of a cirque.

equilibrium between the gain and loss of heat at a specific place or for a specific system.

the equilibrium that exists between the radiation received by the earth and atmosphere from the sun and that emitted by the earth and atmosphere.

relation between fluxes of heat into and out of a given region or body and the heat stored by the system; in general, this budget includes advective, evaporative, and other terms as well as a radiation term.

the amount of heat required to raise the temperature of a unit mass of a substance by one degree.

the amount of heat transferred across a surface of unit area in a unit time.

process, or region, in which energy is removed from the atmosphere in the form of heat.

process, or region, in which energy is added to the atmosphere in the form of heat.

upward pressure developed during freezing of the ground.

area of high pressure in the atmosphere; used interchangeably with anticyclone.

an ice-wedge polygon in which melting of the surrounding ice wedges has left the central area in a relatively elevated position.

typically thin, white clouds above 6,000 meters (20,000 feet); at these altitudes, temperatures are so cold that clouds are composed primarily of ice crystals; includes cirrus, cirrocumulus and cirrostratus clouds.

a deposit of interlocking ice crystals (hoar crystals) formed by direct sublimation on objects, usually those of small diameter freely exposed to the air, such as tree branches, plant stems and leaf edges, wires, poles, etc.; the surfaces of these objects are sufficiently cooled, mostly by nocturnal radiation, to cause the direct sublimation of the water vapor contained in the ambient air.

a peak or pinnacle thinned and eroded by three or more glacial cirques.

from the point of view of the submariner, an ice canopy containing no large ice skylights or other features which permit a submarine to surface.

(1) water vapor content of the air. (2) some measure of the water-content of air; see also absolute humidity, relative humidity, specific humidity, dew point.

(1) [sea ice] a smooth hill of ice that forms on the sea ice surface from eroding ridges, particularly during the summer melt; the formation of hummocks is similar to young mountain peaks with steep slopes that erode into smooth, rolling hills. (2) [frozen ground] Small lumps of soil pushed up by frost action, often found in uniformly spaced in large groups. Hummocks can form in areas of permafrost or seasonally frozen ground, and are one of the most common surface features of the Arctic.

[sea ice] pressure process by which floating ice becomes broken up into hummocks.

a form of weathering that affects all rocks; water freezes in pores and cracks, which leads to an increase in specific volume (vol/unit mass) of the water, producing stress that is greater than the tensile strength of all common rocks; ultimately leads to shattering and fracturing of the rocks.

the volume of fluid passing through a unit cross section in unit time under the action of a unit hydraulic potential gradient.

the ratio of the hydraulic conductivity and the storage capacity of a groundwater aquifer.

artificial thawing (and removal) of frozen ground by the use of a stream or jet of water under high pressure.

a layer or body of cryotic (but unfrozen) ground in a permafrost area, maintained by moving mineralized groundwater.

any product of condensation or sublimation of atmospheric vapor, whether formed in free atmosphere or at the earth's surface; also any water particles blown by the wind from the earth's surface.

a layer or body of noncryotic unfrozen ground in a permafrost area, maintained by moving groundwater.

an instrument which measures the water vapor content in the atmosphere; there are several different means of transduction used in measuring this quantity and hence various types of hygrometers; these are: a) the psychrometer, which utilizes the thermodynamic method; b) the class of instruments which depends upon a change of physical dimension due to absorption of moisture (hair hygrometer, for example); c) those which depend upon condensation of moisture (dew point hygrometer); d) the class of instruments which depend upon the change of chemical or electrical properties due to absorption of moisture, and some others.

the solid crystalline form of water.

a mass of ice adhering to a mountainside.

white glare on the underside of low clouds indicating presence of ice which may be beyond the range of vision.

a floe smaller than 20 meters (66 feet) across.

pack ice from the point of view of the submariner.

a dome-shaped mass of glacier ice that spreads out in all directions; an ice cap is usually larger than an icefield but less than 50,000 square-kilometers (12 million acres).

a cave of ice, usually underneath a glacier and formed by meltwater; cave entrances are often enlarged near a glacier terminus by warm winds; most common on stagnant portions of glaciers.

a concentration of sea ice, covering 100's of square kilometers, which is found in the same region every summer.

the fraction of an area that is covered by sea ice.

the amount of ice contained in frozen or partially frozen soil or rock.

a core sample drilled from the accumulation of snow and ice over many years that have recrystallized and have trapped air bubbles from previous time periods, the composition of which can be used to reconstruct past climates and climate change; typically removed from an ice sheet (Antarctica and Greenland) or from high mountain glaciers elsewhere.

land overlaid at present by a glacier is said to be covered; the alternative term glacierized has not found general favour.

the boundary separating opposing flow directions of ice on a glacier or ice sheet.

the boundary at any given time between open water and sea, river or lake ice of any kind, whether drifting or fast; may be termed compacted when it is clear-cut, or open when it forms the indefinite edge of an area of dispersed ice.

the total area covered by some amount of ice, including open water between ice floes; ice extent is typically reported in square kilometers.

a cohesive sheet of ice floating in the water; the sea ice cover is made up of conglomerates of floes; ice floes are not unique to sea ice, as they also occur in rivers and lakes.

a suspension of numerous minute ice crystals in the air, reducing visibility at the earth's surface; the crystals often glitter in the sunshine; ice fog produces optical phenomena such as luminous pillars and small haloes.

a very narrow ice piedmont, extending less than about 1 km inland from the sea.

the vertical cliff forming the seaward face of an ice shelf or other floating glacier, varying in height from 2 to 50 meters (2.2 to 55 yards) above sea level.

a form of tabular berg found in the Arctic Ocean, with a thickness of 30 - 50 meters (33 to 55 yards) and an area from a few thousand square meters to 500 square kilometers (123,550 acres); ice islands often have an undulating surface, which gives them a ribbed appearance from the air.

an accumulation of broken river or sea ice caught in a narrow channel.

from the point of view of the submariner, a downward-projecting ridge on the underside of the ice canopy; the counterpart of a ridge; ice keels may extend as much as 50 meters (55 yards) below sea level.

a dominantly horizontal, lens-shaped body of ice of any dimension.

the average position of the ice edge in any given month or period based on observations over a number of years.

a research ship which performs ice surveys in polar regions.

precipitation of small balls or pieces of ice (hailstones) with a diameter ranging from 5 to 50 millimeters (0.2 to 2.0 inches), or sometimes more, falling either separately or agglomerated into irregular lumps; when the diameter is less that about 5 millimeters (0.2 inch), the balls are called ice pellets.

ice covering a costal strip of low-lying land backed by mountains; the surface of an ice piedmont slopes gently seawards and may be anything from 1 to 50 kilometers (0.6 to 31 miles) wide, fringing long stretches of coastline with ice cliffs; ice piedmonts frequently merge into ice shelves; a very narrow ice piedmont may be called an ice fringe.

a fall of unbranched ice crystals, in the form of needles, columns, or plates, often so tiny that they seem to be suspended in the air; these are visible mainly when they glitter in the sunshine (diamond dust); they may then produce a luminous pillar or other halo phenomena; this hydrometeor, which is frequent in polar regions, occurs at very low temperatures and in stable air masses.

a shaking of ice caused by crevasse formation or jerky motion.

a brittle, shiny crust of floating ice, formed on a quiet surface by direct freezing or from grease ice, usually in water of low salinity; thickness less than 5 centimeters (2 inches); easily broken by wind or swell, commonly breaking into rectangular pieces.

a mass of ice resting on rock and surrounded either by an ice shelf, or partly by an ice shelf and partly by sea; no rock is exposed and there may be none above sea level; ice rises often have a dome-shaped surface; the largest known is about 100 kilometers (62 miles) across.

the formation of discrete layers or lenses of segregated ice in freezing mineral or organic soils, as a result of the migration (and subsequent freezing) of pore water.

a dome-shaped mass of glacier ice that covers surrounding terrain and is greater than 50,000 square kilometers (12 million acres) (e.g., the Greenland and Antarctic ice sheets).

portion of an ice sheet that spreads out over water.

from the point of view of the submariner, thin places in the ice canopy, usually less than 1 meter (3.3 feet) thick and appearing from below as relatively light, translucent patches in dark surroundings; the under-surface of an ice skylight is normally flat; ice skylights are called large if big enough for a submarine to attempt to surface through them (120 meters, 131 yards), or small if not.

(1) a current of ice in an ice sheet or ice cap that flows faster than the surrounding ice (2) sometimes refers to the confluent sections of a branched-valley glacier (3) obsolete synonym of valley glaciers.

an ice-filled crack or fissure in the ground.

an ice cliff forming the seaward margin of an inland ice sheet, ice piedmont or ice rise; the rock basement may be at or below sea level.

narrow ice mass that is 3 to 4 meters (10 to 13 feet) wide at the ground surface, and extends as much as 10 meters (33 feet) down; a decrease in temperature during the winter leads to ice wedge cracks in the ground around ice wedges; during the summer, these cracks accumulate melt-water and sediment, forming pseudomorphs.

an oligochaete worm that lives on temperate glaciers or perennial snow; there are several species that range in color from yellowish-brown to reddish-brown or black; they are usually less than 1 millimeter (0.04 inch) in diameter and average about 3 millimeters (0.1 inch) long; some eat red algae.

permafrost that contains ice.

ice-bearing permafrost in which the soil particles are cemented together by ice.

a rock glacier that has interstitial ice a meter or so below the surface.

a rock glacier that has a buried core of ice.

topography that is due almost solely to differences in the amount of excess ice underlying its surface.

the temperature at which ice first forms during freezing of a soil/water system that does not initially contain ice.

permafrost containing excess ice.

a filling of sediment in the space formerly occupied by an ice wedge.

a polygon outlined by ice wedges underlying its boundaries.

a piece of ice that has broken off from the end of a glacier that terminates in water.

a major accumulation of icebergs projecting from the coast, held in place by grounding and joined together by fast ice.

a harbour, inlet, etc, is said to be icebound when navigation by ships is prevented due to ice, except possibly with the assistance of an icebreaker.

part of a glacier with rapid flow and a chaotic crevassed surface; occurs where the glacier bed steepenes or narrows.

a mass of glacier ice; similar to an ice cap, and usually smaller and lacking a dome-like shape; somewhat controlled by terrain.

a narrow fringe of ice attached to the coast, unmoved by tides and remaining after the fast ice has broken free.

the low pressure center near Iceland (mainly between Iceland and southern Greenland); on mean charts of sea-level pressure, it is a principal center of action in the atmosphere circulation of the northern hemisphere.

an embayment in an ice front, often of temporary nature, where ships can moor alongside and unload directly into the ice shelf.

hanging spike of clear ice formed by the freezing of dripping water.

a qualitative term describing the quantity of ice in frozen ground.

a sheetlike mass of layered ice formed on the ground surface, or on river or lake ice, by freezing of successive flows of water that may seep from the ground, flow from a spring or emerge from below river or lake ice through fractures.

a seasonal frost mound consisting only of ice and formed at least in part through lifting of one or more layers of an icing by injected water.

an area kept clear of trees and shrubs by the annual occurrence of icings.

a seasonal frost mound consisting exclusively of thinly layered ice, formed by freezing of successive flows of water issuing from the ground or from below river ice.

an ice wedge that is no longer growing.

a mass of rock fragments and finer material, on a slope, that contains either an ice core or interstitial ice, and shows evidence of past, but not present, movement.

electromagnetic radiation of wavelengths between approximately 0.75 and 1000 millimeters; see also atmospheric radiation, terrestrial radiation, longwave radiation.

an ice sheet of considerable thickness and an area of more than about 50,000 square kilometers (12.4 million acres), resting on rock; inland ice sheets near sea level may merge into ice shelves.

(1) exposure of an object to the sun (2) intensity of incoming solar radiation incident on a unit horizontal surface at a specific level.

structure to protect certain instruments from insolation and weather while at the same time ensuring sufficient ventilation.

water that forms transition layers at mineral/water and mineral/water/ice interfaces in frozen ground.

(1) (North American usage) permafrost underlying 35 - 65% of the area of exposed land surface (2) (Russian usage) permafrost underlying 40 - 60% of the area of exposed land surface.

a measure of the compactness, or strength of the ice; plays an important role in the deformation of the ice and formation of features such as ridges and leads.

ice formed in narrow spaces between small rocks and sediment in soil.

water occurring in unfrozen zones (taliks and cryopegs) within permafrost.

ice formed from water injected into soils or rocks.

in meteorology, a departure from the usual (normal) decrease or increase with altitude of the value of an atmospheric property; also, the layer through which this departure occurs (the inversion layer); this term almost always refers to a temperature inversion.

a distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form subhorizontal layers of similar thickness.

a line of equal or constant pressure; it most often refers to a line drawn through all points of equal atmospheric pressure.

a line drawn through geographical points recording equal amounts of precipitation during a specific period.

a body of unfrozen ground, that is perennially cryotic (T < 0 degrees Celsius) and entirely surrounded by perennially frozen ground.

permafrost underlying less than 10% of the exposed land surface.

a layer or body of unfrozen ground entirely surrounded by perennially frozen ground.

a line of equal or constant temperature.

relatively strong winds concentrated within a narrow stream in the atmosphere; generally refers to a quasi-horizontal jet stream of maximum winds embedded in the midlatitude westerlies, and concentrated in the high troposphere.

(1) a large outburst flood that usually occurs when a glacially dammed lake drains catastrophically (2) any catastrophic release of water from a glacier.

any wind blowing down an incline; if the wind is warm, it is called a foehn or chinook; if cold, it may be a fall wind (bora), or a gravity wind (mountain wind); the opposite of anabatic wind.

the part of a ridge below the ocean surface; wind, ocean currents, and other forces can push sea ice into piles that rise and form small mountains below the level sea ice surface.

snow metamorphism that builds angular facets on crystals and makes cup and scroll shaped crystals.

a general term for all types of coarse clastic formations on slopes of 2-3 to 40 degrees, moving downslope mainly due to creep.

floating ice formed in lakes.

a layer or body of unfrozen ground occupying a depression in the permafrost table beneath a lake.

thin plate, sheet or layer; laminae (plural).

the relatively dark appearance of the underside of a cloud layer when it is over land that is not snow covered; this term is used largely in polar regions with reference to the sky map; land sky is brighter than water sky, but is much darker than ice blink or snow blink.

the rate of change of any meteorological element with height.

atmospheric processes with a representative scale (large-scale) of 10,000 kilometers (6,200 miles); in meteorology, it is a scale in which the curve of the earth is not negligible; the large-scale atmospheric flows are essentially nearly hydrostatic, nearly geostrophic and wave-like in appearance; they exist mainly in response to the latitudinal differences in radiative heating, to the particular value of the coriolis force and to the spatial distribution of the oceans and continents.

the amount of heat required to cause a change of phase from solid to liquid, or the heat released when the phase change is from liquid to solid; in the case of melting snow, the phase change from ice to water requires a significant amount of heat—160 times that required to raise the temperature of the same amount of ice by just 1 degree Celsius; until the required amount of heat is supplied to completely melt all of the ice being considered, no further increase in temperature will occur.

a polynya that forms from strong winds in a persistent direction that push the ice away from a barrier (the coast, fast ice, a grounded iceberg, or an ice shelf).

a ridge-shaped moraine deposited at the side of a glacier and composed of material eroded from the valley walls by the moving glacier.

a layer or body of unfrozen ground, overlain and underlain by perennially frozen ground.

the southernmost (northernmost) latitude at which permafrost occurs in a lowland region in the northern (southern) hemisphere.

the subdivision of a permafrost region into permafrost zones, based on the percentage of the area that is underlain by permafrost.

the cryostructure of frozen silt or loam in which ice layers alternate with mineral layers that have a massive cryostructure.

long, linear areas of open water that range from a few meters to over a kilometer in width, and tens of kilometers long; they develop as ice diverges, or pulls apart.

a lead that forms between drift ice and the coast.

the downwind side.

ground ice occurring as ice lenses.

the cryostructure of frozen silt or loam containing numerous ice lenses.

floating ice with a flat surface which has never been hummocked.

general term for dry atmospheric suspensoids, including dust, haze, smoke and sand.

a period of cooling that occurred from the 16th through the early 19th century, and was marked by expanding glaciers in Europe, North America, and Asia

the failure strength of a material after a long period of creep deformation.

heat radiation with wavelengths greater than 4 millimeters.

area of low pressure in the atmosphere.

an ice-wedge polygon in which thawing of ice-rich permafrost has left the central area in a relatively depressed position.

clouds in the lower region of the atmosphere, from ground level to 6500 feet (2000 meters); includes stratus, stratocumulus, the bases of cumulus and cumulonimbus, and sometimes nimbostratus clouds.

white or sometimes reddish vertical streaks of light extending from above and below the sun; they are caused by light reflected off the mirror-like surfaces of ice; most commonly seen at sunrise and sunset.

closed, multi-sided, roughly equidimensional, patterned ground features, typically 15 to 30 meters (16 to 33 yards) across; commonly resulting from thermal contraction cracking of the ground.

either of the two points on the earth's surface at which magnetic meridians converge; the horizontal component of the magnetic field of the earth becomes zero at this point; also called the dip pole.

a crevasse near the side of a glacier formed as the glacier moves past stationary valley walls; usually oriented about 45 degrees up-glacier from the side wall.

a part of the seasonal ice zone that varies in width (100 to 200 kilometers, 62 to 124 miles) that extends from the ice edge into the ice pack, where waves and swells affect the ice; often characterized by highly variable ice conditions; in general, it is wider in the Antarctic than the Arctic.

a climate dominated by the ocean; because of the moderating effect of water, sites having this climate are considered relatively mild.

a layer or body of unfrozen ground, that is perennially cryotic (T < 0 degrees Celsius), forming part of the coastal or subsea permafrost.

of, relating to, or adjacent to the sea.

the difference between accumulation and ablation on a glacier; usually calculated on an annual basis.

downslope movement of soil or rock on, or near, the earth's surface under the influence of gravity.

the cryostructure of frozen sand in which all mineral particles are bonded together with ice.

a comprehensive term used to describe large masses of ground ice, including ice wedges, pingo ice, buried ice and large ice lenses.

the cryostructure of frozen silt or loam in which ice veins form an irregular three-dimensional network.

the cryostructure of frozen sand and gravel in which all mineral particles are bonded together with ice, but larger pore spaces are not completely filled with ice.

the largest sea ice extent during a given year; maximum ice extent marks the end of the growth period for sea ice, and the start of the melt season

mean annual temperature of the ground at a particular depth.

mean annual temperature of the surface of the ground.

the properties of frozen ground governing its deformability and strength.

the failure strength of a material under given loading conditions.

a ridge-shaped moraine in the middle of a glacier originating from a rock outcrop, nunatak, or the converging lateral moraines of two or more ice streams.

unlike snow dunes that are piles of drifted snow, antarctic megadunes are long, undulating waves in the surface of the ice sheet that are 2 to 4 meters (6.5 to 13 feet) high and 2 to 5 kilometers (1 to 3 miles) apart; they are slightly rounded at their crests and are so subtle that a person on the ground cannot see the pattern.

pools of melted snow and ice on the sea ice surface created during the summer melt.

a channel within, underneath, on top of, or near the side of a glacier that drains meltwater out of the glacier; usually kept open by the frictional heating of flowing water that melts the ice walls of the conduit.

a mercury-filled glass tube in which the height of the mercury column is a measure of air pressure.

an atmospheric circulation in a vertical plane oriented along a meridian; it consists of the vertical and the meridional (north or south) components of motion only.

top of the mesosphere, situated at about 80-85 kilometers (50-53 miles).

the region of the atmosphere between about 50 kilometers (31 miles) and 80-85 kilometers (50-53 miles), extending from the top of the stratosphere to the upper temperature minimum; it is characterized by a broad temperature maximum (near 0 degrees Celsius) at its base, from which the temperature decreases to a minimum (about -90 degrees Celsius) at the mesopause level.

changes in the structure and texture of snow grains which result from variations in temperature, migration of liquid water and water vapor, and pressure within the snow cover.

any one of the properties or conditions of the atmosphere which together specify the weather at a given place for any particular time (for example, air temperature, pressure, wind, humidity, thunderstorm and fog).

study of the atmosphere and its phenomena, including its structure, properties, and physical processes.

closed, multi-sided, roughly equidimensional, patterned ground features, less than 2 meters (6.6 feet) in diameter; usually caused by desiccation cracking of fine-grained soil materials.

in terms of wavelength, microwaves range from 1 millimeter to 1 meter, and are much longer than the shorter visible (0.38-0.78 micrometer) wavelengths; these longer wavelengths allow microwave energy to penetrate through clouds; because these sensors measure microwave energy, they do not rely on sunlight for illumination so they can acquire images regardless of time of day; can be either passive or active; passive sensors detect and record naturally upwelling microwave energy emitted from objects; active sensors generate their own beam of energy, generally with an antenna, which then detects the returned energy patterns (backscatter) that indicate the presence of features and their position relative to the sensor; radar (radio detection and ranging) was an original active microwave sensor that became widely operational with the onset of World War II.

clouds composed of ice crystals and water droplets in the middle region of the atmosphere, from 2,000 - 6,000 meters (6,500 to 23,000 feet); includes altocumulus, altostratus, nimbostratus, and portions of cumulus and cumulonimbus clouds.

a palsa in which the frozen core extends below the peat into underlying mineral material.

Also known as tundra mires, generally described as an area of wet, soggy, muddy ground., and often feature a layer of peat over permafrost.

precipitation consisting of a mixture of rain and wet snow; it usually occurs when the temperature of the air layer near the ground is slightly above freezing; the British term for this mixture is sleet (which has a different meaning in the United States).

a mound, ridge, or other distinct accumulation of glacial till.

glacial moraine that has formed a shallow place in water.

a nearly vertical channel in ice that is formed by flowing water; usually found after a relatively flat section of glacier in a region of transverse crevasses; also called a pothole.

a glacier that is confined by surrounding mountain terrain; also called an alpine glacier.

permafrost existing at high altitudes in high, middle, and low latitudes.

a cold wind blowing down an incline; a kind of katabatic wind.

a type of nonsorted circle developed in fine-grained materials.

a type of mass movement associated with shear failure in unfrozen sediments underlying permafrost, leading to detachment of blocks of frozen ground that move downslope.

ice that has survived at least one melt season; it is typically 2 to 4 meters (6.6 to 13.1 feet) thick and thickens as more ice grows on its underside.

the ratio of the surface freezing or thawing index to the air freezing or thawing index.

thin, elongated ice crystals that form perpendicular to the ground surface.

a geyser; a fountain that develops when water from a conduit is forced up to the surface of a glacier.

the difference between accumulation and ablation; usually expressed in terms of volumes of water equivalent per unit area.

difference between the downward and upward terrestrial radiation fluxes; net flux of terrestrial radiation.

a general category of ice that consists of frazil, grease ice, slush, and shuga.

a recent snow deposit in which the original form of the ice crystals can be recognized.

very small glacier that occupies gullies and hollows on north-facing slopes (northern hemisphere); may develop into cirque glacier if conditions are favorable.

a thin sheet of smooth, level ice less than 10 centimeters (4 inches) thick; appear darkest when thin.

a principal cloud type (cloud genus); gray and often dark; rendered diffuse by more or less continuously falling rain, snow, sleet, etc. of the ordinary varieties and not accompanied by lightning, thunder, or hail; precipitation in most cases reaches the ground; may or may not merge with low, ragged clouds that frequently occur below.

ice is said to nip when it forcibly presses against a ship which is beset; a vessel so caught, though undamaged, is said to have been nipped.

soil or rock at temperatures above 0 degrees Celsius.

a patterned ground form that is equidimensional in several directions, with a dominantly circular outline which lacks a border of stones.

a patterned ground with cells that are equidimensional in several directions, neither dominantly circular nor polygonal, and lacking borders of stones.

a patterned ground form that is equidimensional in several directions, with a dominantly polygonal outline which lacks a border of stones.

a patterned ground feature with a step-like form and a downslope border of vegetation embanking an area of relatively bare ground upslope.

form patterned ground with a striped and nonsorted appearance, due to parallel strips of vegetation-covered ground and intervening strips of relatively bare ground, oriented down the steepest available slope.

the relatively weak general area of high pressure which, as shown on mean charts of sea-level pressure, covers most of North America during winter; this pressure system is not nearly as well-defined as the analogous Siberian high.

an oscillation in the strength of the Icelandic Low and Azores High, the two dominant surface pressure features in the North Atlantic. When both are unusually strong, the North Atlantic Oscillation (NAO) is in its positive phase; when both are unusually weak, it is in its negative phase. The NAO has climate impacts not just in the Arctic, but in North America and Europe. The NAO, identified by Sir Gilbert Walker in the 1920s, is similar to the Arctic Oscillation.

90° N latitude; one of the two points where the Earth's axis of rotation meets the Earth's surface (the other being the south pole, diametrically opposite).

a rocky crag or small mountain projecting from and surrounded by a glacier or ice sheet.

(1) young, granular snow that has been partially melted, refrozen and compacted; névé that survives a full season is called firn; firn becomes glacial ice; (2) also refers to the accumulation zone of a glacier.

a weather or meteorological observation is an evaluation of one or more meteorological elements that describes the state of the atmosphere either at the earth's surface or aloft.

a group of stations (surface meteorological, upper-air, or other) spread over a given area for making regular observations.

alternate bands of light and dark ice seen on a glacier surface.

sea ice more than 2-years-old, up to 3 meters (10 feet) or more thick; hummocks on old ice are even smoother than in second-year ice, and the ice is almost salt-free; when old ice is bare of snow, it is blue and lacks the greenish tint of second-year ice.

deposited snow whose transformation into firn is so far advanced that the original form of the ice crystals can no longer be recognized.

permafrost occurring beneath exposed land surfaces.

a lead that connects two open bodies of water; ships can traverse between them through this lead; it also refers to a lead where open water is found, or a lead that has not completely frozen.

composed of floes seldom in contact and with many leads; ice cover 4/10ths to 6/10ths.

a body of unfrozen ground that penetrates the permafrost completely, connecting suprapermafrost and subpermafrost water.

a large area of freely navigable water in which floes may be present in concentration under 1/10th; if there is no sea ice present, the area may be termed open water, even though icebergs are present.

ice formed in an open cavity or crack in the ground by reverse sublimation of water vapour.

freezing that occurs under conditions that allow gain or loss of water by the system.

a pingo formed by doming of frozen ground; caused by groundwater that moves downslope through taliks and onto the pingo surface, where it freezes.

a distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which coarser soil particles form circular to ellipsoidal patterns.

an organic soil having a surface layer containing more than 17% organic carbon by weight, with permafrost within 1 meter (3.3 feet) below the surface.

one of a group of lakes possessing a common, preferred, long-axis orientation.

any catastrophic flooding from a glacier; may originate from trapped water in cavities inside a glacier or at the margins of glaciers or from lakes that are dammed by flowing glaciers.

a valley glacier which drains an inland ice sheet or ice cap and flows through a gap in peripheral mountains.

a nearly colorless (but faintly blue) gaseous form of oxygen, with a characteristic odor like chlorine; has a formula of O3 and a molecular weight of 48; found in trace quantities in the earth's atmosphere at all times, primarily in the stratosphere between heights of about 10 to 50 kilometers (6 to 31 miles; the ozonosphere or ozone shield) where its production results from photochemical processes involving ultraviolet radiation; its maximum concentration occurs between 20 to 25 kilometers (12 to 16 miles); in the lower atmosphere, ozone is commonly formed as a product of electrical discharges through the air.

stratospheric ozone layer, giving protection to the earth's surface due to intense absorption of harmful solar ultraviolet radiation by the gas.

stratospheric ozone layer, giving protection to the earth's surface due to intense absorption of harmful solar ultraviolet radiation by the gas.

ice that is not attached to the shoreline and drifts in response to winds, currents, and other forces; some prefer the generic term drift ice, and reserve pack ice to mean drift ice that is closely packed.

a peaty permafrost mound possessing a core of alternating layers of segregated ice and peat or mineral soil material.

a poorly-drained lowland underlain by organic-rich sediments, which contains perennially frozen peat bodies (peat plateaux) and, occasionally, palsas.

pieces of new ice approximately circular, up to 10 centimeters (4 inches) thick and 0.03 to 3 meters (0.1 to 9.8 feet) in diameter, with raised edges that form from rubbing against each other; formed from the freezing together of grease ice, slush or shuga, or the reaking up of ice rind or nilas.

(1) a term used loosely by many meteorologists for almost any meteorological quantity or element (2) an arbitrary constant or variable appearing in a mathematical expression; changing it can give various outcomes for the phenomena represented.

in a mixture of gases, each gas has a partial pressure, which is the pressure the gas would have if it occupied that volume alone.

ice-bearing permafrost in which some of the soil particles are not held together by ice.

special design and construction methods used for engineering works in permafrost areas where preservation of the frozen condition is feasible.

a foundation pile provided with a single-phase natural convection cooling system to remove heat from the ground.

a foundation pile provided with a two-phase natural convection cooling system to remove heat from the ground.

predominant characteristic of the weather which had existed at an observing station during a given period of time (during the preceding hour or six hours), specified in the international synop code.

a collection of pack ice, less than 10 kilometers (6.2 miles) across, whose limits can be seen from the masthead.

a general term for any ground surface exhibiting a discernibly ordered, more or less symmetrical, morphological pattern of ground and, where present, vegetation.

a deposit consisting of decayed or partially decayed humified plant remains.

a hummock consisting of peat.

a generally flat-topped expanse of peat, elevated above the general surface of a peatland, and containing segregated ice that may or may not extend downward into the underlying mineral soil.

peat-covered terrain.

the extreme relief of ablation hollows found most often at high altitudes in the tropics; the resulting spikes of snow resemble repentant souls.

a layer of frozen ground which forms as part of the seasonally frozen ground (in areas free of permafrost or with a lowered permafrost table); remains frozen throughout one or several summers, and then thaws.

snow that persists on the ground year after year.

the conditions, processes and landforms associated with cold, nonglacial environments.

landforms and soil characteristics produced by periglacial processes.

processes associated with frost action in cold, nonglacial environments.

an artificial mixture of frozen soil materials cemented by pore ice, which forms a concrete-like construction material used in cold regions.

layer of soil or rock, at some depth beneath the surface, in which the temperature has been continuously below 0°C for at least several years; it exists where summer heating fails to reach the base of the layer of frozen ground.

a naturally or artificially caused increase in the thickness and/or areal extent of permafrost.

the lower boundary surface of permafrost, above which temperatures are perennially below 0 degrees Celsius (cryotic) and below which temperatures are perennially above 0 degrees Celsius (noncryotic).

(1) the geographical boundary between the continuous and discontinuous permafrost zones (2) the margin of a discrete body of permafrost.

a naturally or artificially caused decrease in the thickness and/or areal extent of permafrost.

the total geographic area containing some amount of permafrost; typically reported in square kilometers.

outermost (latitudinal) or lowest (altitudinal) limit of the occurrence of permafrost.

a region in which the temperature of some or all of the ground below the seasonally freezing and thawing layer remains continuously at or below 0 degrees Celsius for at least two consecutive years.

the upper boundary surface of permafrost.

the vertical distance between the permafrost table and the permafrost base.

a major subdivision of a permafrost region.

a region that is covered with sea ice year-round; most of the sea ice in the permanent ice zone is multiyear ice, but younger ice and open water may still be present; the permanent ice zone is what remains in summer after all melting has occurred (often called the summer minimum extent).

power of hydrogen; a measure of the activity of hydrogen ions in solution, and therefore, its acidity or alkalinity.

large ice lobe spread out over surrounding terrain, associated with the terminus of a large mountain valley glacier.

an eskimo term for a perennial frost mound consisting of a core of massive ice with soil and vegetation cover; the size can range from a few meters to tens of meters, in both diameter and height; can be found in continuous and discontinuous permafrost zones.

massive ice forming the core of a pingo.

a collapsed pingo.

a pingo remnant in a contemporary non-permafrost environment.

permafrost occurring on other planetary bodies (planets, moons, asteroids).

fine-grained soil in which only a portion of the pore water has turned into ice.

part of the geologic timescale, corresponding to the time period from 1.81 million to 11,550 years before the present.

the absolute value of the ratio between linear strain changes, perpendicular to and in the direction of a given uniaxial stress change.

in polar regions, the portion of the year when the sun is continuously in the sky; its length changes from twenty hours at the arctic/antarctic circle (latitude 66 degrees, 33 minutes N or S) to 186 days at the north and south poles.

a person working for a long time at one of the polar observing stations; Russian word is polyarnik.

a glacier entirely below freezing, except possibly for a thin layer of melt near the surface during summer or near the bed; polar glaciers are found only in polar regions of the globe or at high altitudes.

a high-latitude region covered in ice; not a true ice cap, which are less than 50,000 square kilometers (12.4 million acres) and are always over land; more like an ice sheet; also called polar ice sheet.

small, shallow depression which forms mainly in winter over some high-latitude seas within a polar or arctic air mass; its motion is approximately the same as the air stream in which it is embedded.

in polar regions, the portion of the year when the sun does not rise above the horizon; its length changes from twenty hours at the arctic/antarctic circle (latitude 66 degrees, 33 minutes N or S) to 179 days at the North and South Poles.

regions around the North and South Poles, north of the Arctic, or south of the Antarctic Circles, respectively; characterized by polar climate, very cold temperatures, heavy glaciation, and dramatic variations in daylight hours (24 hrs darkness in winter, 24 hrs daylight in summer).

large-scale cyclonic circulation in the middle and upper troposphere centered generally in the polar regions; it is often called circumpolar vortex.

in the northern hemisphere, the point in the Arctic Ocean farthest from land; in the southern hemisphere, the point on the Antarctic continent farthest from the Southern Ocean.

Russian word for a person working for a long time at one of the polar observing stations.

a snowflake composed of many individual ice crystals.

literally means many angled; polygons are closed, multi-sided, roughly equidimensional shapes, bounded by more or less straight sides; some of the sides may be irregular; in cryospheric science, it refers to patterned ground formations.

the narrow depression surrounding a high-centre polygon.

a pattern consisting of numerous multi-sided, roughly equidimensional figures bounded by more or less straight sides.

a peat plateau with ice-wedge polygons.

irregularly shaped areas of persistent open water that are sustained by winds or ocean heat; they often occur near coasts, fast ice, or ice shelves.

ice-bearing permafrost in which few of the soil particles are held together by ice.

ice occurring in the pores of soils and rocks.

water occurring in the pores of soils and rocks.

a nearly vertical channel in ice that is formed by flowing water; usually found after a relatively flat section of glacier in a region of transverse crevasses; also called a moulin.

a thin, dry snow surface which is composed of loose, fresh ice crystals.

a treeless grassy plain.

(1) any of the forms of water particles, whether liquid or solid, that fall from the atmosphere and reach the ground; includes: rain, drizzle, snow, snow grains, snow pellets, diamond dust, hail, and ice pellets; see also acid precipitation (2) accumulated depth of rain, drizzle and the melted water content of frozen forms of precipitation.

the degree of agreement between independent measurements of a single quantity obtained by applying a specific measurement procedure several times under prescribed conditions.

weather at a station at the time of observation.

a type of stress characterized by uniformity in all directions; in dynamics, it is that part of the stress tensor that is independent of viscosity and depends only upon the molecular motion appropriate to the local temperature and density; it is the negative of the mean of the three normal stresses, and is, therefore, a scalar quantity expressed in units of force per unit area; in meteorology, commonly used for atmospheric pressure.

a general term for floating ice which has been squeezed together and in places forced upwards; includes rafted ice, telescoped ice, hummocked ice and ridge ice.

melting that occurs in ice at temperatures colder than normal melting temperature because of added pressure.

process that occurs when wind, ocean currents, and other forces push sea ice around into piles that rise and form small mountains above the level sea ice surface; ridges are initially thin and transparent with very sharp edges from blocks of ice piling up; also see keels.

the character and amount of atmospheric pressure change for a three-hour or other specified period ending at the time of observation.

lowering the melting point of ice by applying pressure.

the meridian (line of longitude) defined to be 0 degrees and passing through the Royal Greenwich Observatory in London; also known as the International Meridian or Greenwich Meridian; the Prime Meridian and the opposite 180th meridian (at 180 degrees longitude) separate the Eastern and Western Hemispheres.

in geology, a mineral compound resulting from a process by which the primary mineral component is replaced by another, although the compound maintains constant appearance and dimensions.

an instrument used for measuring the water vapor content of the atmosphere; a type of hygrometer; it consists of two thermometers, one of which (the dry bulb) is an ordinary glass thermometer, while the other (wet bulb) has its bulb covered with a jacket of clean muslin which is saturated with distilled water prior to an observation; when the bulbs are suitably ventilated, they indicate the thermodynamic wet- and dry-bulb temperatures of the atmosphere; one variety is the assman psychrometer (a special form of aspiration psychrometer for which the ventilation is provided by a suction fan).

tables prepared from psychrometric data and used to obtain vapor pressure, relative humidity, and dew point from wet- and dry-bulb temperatures.

an accumulation of melt water on an ice surface, mainly due to melting snow, but in later stages also to the melting of ice; the initial stage consists of patches of slush.

moraine built out ahead of an advancing glacier.

RAdio Detection And Ranging was an original active microwave sensor that became widely operational with the onset of World War II.

(1) emission or transfer of energy in the form of electromagnetic waves (2) the process by which electromagnetic radiation is propagated through free space by virtue of joint undulatory variations in the electric and magnetic fields in space; this concept is to be distinguished from conduction and convection.

instrument intended to be carried by a balloon up through the atmosphere, equipped with sensors to measure one or several meteorological variables (pressure, temperature, humidity, etc.), and provided with a radio transmitter for sending this information to the observing station.

snow metamorphism that occurs when there are large differences in convex and concave portions of a crystal.

deformed sea ice in which one piece has overridden another; also called telescoped ice.

a process by which currents or winds push around thin ice so they slide over each other; also called finger rafting.

a horizontal underwater projection of ice from an ice front, ice wall, iceberg or floe.

a fissure that separates a moving glacier from its headwall rock; like a bergschrund.

radiosonde which is tracked by radar or radio-theodolite to measure the wind aloft.

a glacier that is reconstructed or reconstituted out of other glacier material; usually formed by seracs falling from a hanging glacier then re-adhering; also called reconstructed glacier, regenerated glacier, or glacier remainie.

a glacier that is reconstructed or reconstituted out of other glacier material; usually formed by seracs falling from a hanging glacier then re-adhering; also called reconstituted glacier, regenerated glacier, or glacier remainie.

irregularly shaped areas of persistent open water that are sustained by winds or ocean heat; they often occur near coasts, fast ice, or ice shelves.

algae common on temperate glaciers and perennial snow; its red color sometimes prompts people to call it watermelon snow.

motion of an object through ice by melting and freezing that is caused by pressure differences; this process allows a glacier to slide past small obstacles on its bed.

a glacier that is reconstructed or reconstituted out of other glacier material; usually formed by seracs falling from a hanging glacier then re-adhering; also called reconstituted or reconstructed glacier, or glacier remainie.

The ratio of the absolute error in a measurement to the size of the measurement.

the (dimensionless) ratio of the actual vapor pressure of the air to the saturation vapor pressure; usually expressed as a percent, and can be computed from psychrometric data.

the relative permitivity of a soil is the ratio of the permitivity of the soil to the permitivity of a vacuum.

a layer of ground, now perennially frozen, lying immediately below the modern active layer; its thickness indicates the greater annual depth of thaw that occurred during a previous period.

ice formed in, and remaining from, the geologically recent past.

permafrost existing in areas where permafrost can not form under present climatic conditions; reflects past climatic conditions that were colder.

the effective stress generated in a thawing soil if no volume change is permitted during thaw.

a layer of thawed ground between the seasonally frozen ground and the permafrost table.

the cryostructure in which horizontal and vertical ice veins form a three-dimensional, rectangular or square lattice.

a network of horizontal and vertical ice veins forming a three-dimensional, often rectangular or square lattice.

the cryostructure in which horizontal and vertical ice veins form a three-dimensional, irregular rectangular lattice.

when a mountain glacier's terminus doesn't extend as far downvalley as it previously did; occurs when ablation surpasses accumulation.

a glacier whose terminus is increasingly retreating upvalley compared to its previous position due to a higher level of ablation compared to accumulation.

a slope failure resulting from thawing of ice-rich permafrost.

in meteorology, an elongated area of relatively high atmospheric pressure, almost always associated with and most clearly identified as an area of maximum anticyclonic curvature of wind flow.

piled ice formed by ridging.

process that occurs when wind, ocean currents, and other forces push sea ice around into piles that rise and form small mountains above the level sea ice surface; ridges are initially thin and transparent with very sharp edges from blocks of ice piling up; also see keels.

a white or milky and opaque granular deposit of ice formed by the rapid freezing of super-cooled water drops as they impinge upon an exposed object; it is denser and harder than hoarfrost, but lighter, softer, and less transparent than glaze.

corrugation on a snow surface caused by wind (as on sand).

floating ice formed in rivers.

a layer or body of unfrozen ground occupying a depression in the permafrost table beneath a river.

a fine powder of silt- and clay-sized particles that a glacier creates as its rock-laden ice scrapes over bedrock; usually flushed out in meltwater streams, causing water to look powdery gray; lakes and oceans that fill with glacier flour may develop a banded appearance.

looks like a mountain glacier and has active flow; usually includes a poorly sorted mess of rocks and fine material; may include: (1) interstitial ice a meter or so below the surface (“ice-cemented”), (2) a buried core of ice (“ice-cored”), and/or (3) rock debris from avalanching snow and rock.

floating ice which has become honeycombed in the course of melting, and which is in an advanced state of disintegration.

the part of a ridge above sea level; like a sail on a sailboat, it catches wind and moves the ice.

permafrost in which part or all of the total water content is unfrozen because of freezing-point depression due to a high dissolved-solids content of the pore water.

(1) a general property of aqueous solutions caused by the alkali, alkaline earth, and metal salts of strong acids (Cl, SO4 and NO3) that are not hydrolyzed (2) in soil science, the ratio of the weight of salt in a soil sample to the total weight of the sample.

a wedge-shaped body of sand produced by filling of a thermal contraction crack with sand either blown in from above or washed down the walls of the crack.

a polygon outlined by sand wedges underlying its boundaries.

complex, fragile shapes of snow on top of sea ice that resemble sand dunes; they form parallel to the prevailing wind direction; sastrugi can also form on snow cover over land.

the condition in which the partial pressure of any fluid constituent (water in the atmospheric air) is equal to its maximum possible partial pressure under the existing environmental conditions, such that any increase in the amount of that constituent will initiate within it a change to a more condensed state; evaporation ceases under such conditions.

the maximum amount of water vapor necessary to keep moist air in equilibrium with a surface of pure water; this is the maximum water vapor the air can hold for any given combination of temperature and pressure.

(1) a series of marks at regular intervals for the purpose of measuring (scale of an instrument, for example, a thermometer) (2) system of units for measuring ( 3) proportion between the size of something and the map, diagram, etc. which represents it (4) order of magnitude of a phenomenon or of a meteorological parameter.

any form of ice found at sea which has originated from the freezing of sea water.

see ice extent.

the day of the year when the sea ice covers the largest area of the Arctic or Antarctic.

the day of the year when the sea ice covers the smallest area of the Arctic or Antarctic

evaporation fog formed when water vapor is added to air which is much colder than the vapor's source; most commonly, when very cold air drifts across relatively warm water; also called steam fog.

temperature of the water film at the sea surface.

the atmospheric pressure at mean sea level, either directly measured or, most commonly, empirically determined from the observed station pressure.

the cumulative number of degree-days below 0 degrees Celsius, calculated as the arithmetic sum of all the negative and positive mean daily air temperatures (degrees Celsius) for a specific station during the time period between the highest point in the fall and the lowest point the next spring on the cumulative degree-day time curve.

the occurrence of ground temperatures below 0 degrees Celsius for only part of the year; see also active layer.

an area of ocean that extends from the permanent ice zone to the boundary where winter sea ice extent is at a maximum; here, sea ice is present only part of the year; this zone primarily consists of first-year ice.

(1) snow that accumulates during one season (2) snow that lasts for only one season.

the cumulative number of degree-days above 0 degrees Celsius, calculated as the arithmetic sum of all the positive and negative mean daily air temperatures (degrees Celsius) for a specific station during the time period between the lowest point in the spring and the highest point the next fall on the cumulative degree-day time curve.

ground that freezes and thaws annually.

the active layer in areas without permafrost.

ground that thaws and refreezes annually.

the active layer in permafrost areas.

the uppermost layer of the permafrost which undergoes seasonal phase changes due to the lowered thawing temperature and freezing-point depression of its pore water.

sea ice which has not melted in the first summer of its existence; by the end of the second winter, it attains a thickness of 2 meters (6.6 feet) or more; it stands higher out of the water than first-year ice; summer melting has somewhat smoothed and rounded the hummocks, which accentuation of minor relief by differential melting may have caused others to develop; bare patches and puddles are usually greenish-blue.

alternating bands of light and dark at the firn limit of a glacier; the light bands are usually young and lightest at the highest level up-glacier, becoming increasingly older and darker as they progress down-glacier.

ice in discrete layers or ice lenses, formed by ice segregation.

the ratio of the rate of moisture migration to the temperature gradient in a frozen soil near the 0 degrees Celsius isotherm.

high pressure area largely predominate during a major portion of the year where an anticyclone appears on the mean monthly pressure charts.

slowly moving or motionless cyclone.

same as enthalpy; the heat absorbed or transmitted by a substance during a change of temperature which is not accompanied by a change of state; used in meteorology in contrast to latent heat.

a polynya that forms from the upwelling of warm (above-freezing) ocean water from lower depths; these can form in mid-ocean areas, far from coasts or other barriers.

an isolated block of ice that is formed where the glacier surface is fractured.

in geology, describes the compressive strength (ability to withstand pushing forces) of soils; results from two internal mechanisms: cohesion between soil particles, and friction caused by contact between particles; variable among different soils.

a screen to shield a rain-gauge from the influence of the wind, or to shield a thermometer against insolation.

a stretch of navigable water between pack ice and the shore.

the failure strength of a material under a short-term loading (e.g. up to about 10 minutes in a uniaxial compression test).

in meteorology, a term used loosely to distinguish radiation in the visible and near-visible portions of the electromagnetic spectrum (roughly 0.4 to 4.0 microns in wavelength) from longwave (terrestrial) radiation.

a form of new ice, composed of spongy, white lumps a few cm across, that tend to form in rough seas; they resemble slushy snow balls.

an area of high pressure which forms over Siberia in winter, and which is particularly apparent on mean charts of sea-level pressure.

very old, thick sea ice that forms in fjords; it often resembles glacial ice, because snow can pile up on the ice over many years.

a passive heat transfer device, filled with either a liquid or a gas, installed to remove heat from the ground.

the bonding together of ice crystals.

(1) (United States) frozen raindrops that bind on impact with the ground (2) (elsewhere) a mix of rain and snow, a mix of rain and hail, or melting snow.

mass movement of earth material down a slope; includes landslides, mudslides, debris flows, avalanches, etc; speed of movement can be sudden and catastrophic or slow.

a mixture of snow and grease ice.

common near the snow line on a relatively flat portion of a glacier where melting snow forms slush.

currently used as a synonym for general air pollution; it was originally created by combining the words smoke and fog.

(1) an ice particle formed by sublimation of vapor in the atmosphere (2) a collection of loosely bonded ice crystals deposited from the atmosphere; high density snow (greater than 550 kilograms per cubic meter; 34 pounds per cubic foot) is called firn if it is older than one year.

horseshoe-shaped snowdrift, with the ends pointing down-wind.

a specially constructed board used to identify the surface of snow that has been recently covered by snowfall.

an arch formed by snow which has drifted aross a crevasse, forming first a cornice, and ultimately a covering which may completely obscure the opening.

a sample of snow, either just the freshly fallen snow or the combined old and new snow on the ground, obtained by pushing a cylinder down through the snow layer and extracting it.

(1) in general, the accumulation of snow on the ground surface (2) the areal extent of snow-covered ground, usually expressed as percent of total area in a given region.

the mass of snow per unit volume which is equal to the water content of snow divided by its depth.

the combined total depth of both old and new snow on the ground.

the total land area covered by some amount of snow; typically reported in square kilometers.

snow that falls for short durations and which often changes in intensity; flurries usually produce little accumulation.

precipitation in the form of very small, white opaque ice particles; they resemble snow pellets but are more flattened and elongated, with a diameter less than 1 mm; the solid equivalent of drizzle.

a layer of ice crystals with similar size and shape.

the minimum elevation of snow lying on the ground or glacier surface; the snow line at the end of an ablation season marks a glacier's current equilibrium line.

the downward force on an object or structure caused by the weight of accumulated snow.

relatively small area of snow cover remaining after the main snowmelt period.

precipitation in the form of small, white opaque ice particles; resemble ice grains, but are round (sometimes conical) and about 2-5 mm in diameter.

roll-like snow formation, caused by a unique combination of snow, wind, temperature and moisture

a brief, but intense fall of snow that greatly reduces visibility and which is often accompanied by strong winds.

the water content obtained from melting.

an oligochaete worm that lives on temperate glaciers or perennial snow; there are several species that range in color from yellowish-brown to reddish-brown or black; they are usually less than 1 millimeter (0.04 inch) in diameter and average about 3 millimeters (0.1 inch) in length; some feed off red algae.

a bright white glare on the underside of clouds, produced by the reflection of light from a snow-covered surface; snowblink is lighter than ice blink, and much lighter than land sky or water sky.

very intense showers of snow, often of short duration, that greatly restrict visibility and produce periods of rapid snow accumulation.

an accumulation or bank of snow formed when wind blows snow against an obstruction; often considerably thicker than the surrounding snowcover.

a semipermanent mass of firn formed by drifted snow behind obstructions or in the ground; also called a catchment glacier or a drift glacier.

the depth of new snow that has accumulated since the previous day or since the previous observation.

a cluster of ice crystals that falls from a cloud.

melting of the snowcover, and also the period during which melting of the snow cover occurs at the end of the winter.

the total snow and ice on the ground, including both new snow and the previous snow and ice which have not melted.

strong wind with snow.

a wedge-shaped body of soil that is different in structure and texture from the surrounding soil.

the total electromagnetic radiation emitted by the sun.

slow downslope flow of saturated unfrozen earth materials.

a fan-like deposit at the base of a slope, produced by solifluction.

geomorphological features of varying scale produced by the process of solifluction.

an isolated, tongue-shaped solifluction feature, up to 25 meters (27 yards) wide and 150 meters (164 yards) or more long; formed by more rapid solifluction on certain sections of a slope showing variations in gradient.

a broad deposit of nonsorted, water-saturated, locally derived materials that is moving or has moved downslope.

a low step, or bench, with a straight or lobate front, the latter reflecting local differences in the rate of solifluction movement.

the point in time when the vertical rays of the sun are striking either the Tropic of Cancer (23 degrees, 30 minutes N, the summer solstice in the northern hemisphere) or the Tropic of Capricorn (23 degrees, 30 minutes S, the winter solstice in the northern hemisphere); represents the longest or shortest day of the year; in the northern hemisphere, the summer solstice falls on or about 21 June, and the winter solstice on or about 22 December.

a patterned ground form that is equidimensional in several directions, with a dominantly circular outline, and a sorted appearance commonly due to a border of stones surrounding a central area of finer material.

a type of patterned ground with cells that are equidimensional in several directions, neither dominantly circular nor polygonal, with a sorted appearance commonly due to borders of stones surrounding central areas of finer material.

a patterned ground form that is equidimensional in several directions, with a dominantly polygonal outline, and a sorted appearance commonly due to a border of stones surrounding a central area of finer material.

a patterned ground feature with a step-like form and a downslope border of stones embanking an area of relatively fine-grained bare ground upslope.

patterned ground with a striped and sorted appearance, due to parallel strips of stones and intervening strips of finer material, oriented down the steepest available slope.

90° S latitude; one of the two points where the Earth's axis of rotation meets the Earth's surface (the other being the north pole, diametrically opposite).

the amount of heat required to raise the temperature of a unit mass of a substance by one degree.

the mass of water vapor per unit mass of air, including the water vapor (usually expressed as grams of water vapor per kilogram of air).

a crevasse pattern that forms where ice slowly spreads out sideways; commonly found near a glacier terminus.

(1) (North American usage) permafrost underlying 10 - 50% of the exposed land surface (2) (Russian usage) permafrost underlying 5 - 30% of the exposed land surface.

either of the two points of intersection of the sun's apparent annual path and the plane of the earth's equator; in the northern hemisphere, the spring (vernal) equinox falls on or about 21 March, and the autumnal equinox on or about 22 September.

air mass having static stability in its lower layers; it is free from convection, has a low degree of turbulence and may have stratiform clouds or fog, or no clouds.

thick ridges that become grounded during the winter and become part of the fast ice zone; while the rest of the fast ice melts during the summer, a stamukhi remains throughout the summer attached to the ocean bottom.

Statistical measurement of the variation in a distribution: In science, standard deviation serves as measure of the spread of the data, or how likely a data point will fall close to the mean.

a mineral soil showing little or no evidence of cryoturbation, with permafrost within 1 meter (3.3 feet) below the surface.

atmospheric pressure observed at a station.

evaporation fog formed when water vapor is added to air which is much colder than the vapor's source; most commonly, when very cold air drifts across relatively warm water; also called sea smoke.

in meteorology, a basic fluid flow which exerts a strong influence upon the direction of movement of disturbances embedded in it; in the atmosphere, it is usually an air flow in the middle or upper troposphere which govern directions of the disturbances at low levels.

a type of nonsorted circle developed in gravelly materials.

the downslope border of stones along a sorted step, embanking an area of relatively fine-grained bare ground upslope.

a solifluction lobe with a stony front.

a solifluction terrace with a stony front.

a fissure at the junction between an inland ice sheet, ice piedmont or ice rise and an ice shelf, the latter being subject to the rise and fall of the tide.

a principal low-level cloud type (cloud genus), predominantly stratiform, in the form of relatively low gray and/or whitish layer, sheet or patch; its elements are often arranged in bands or rolls that lie across the wind; light rain, snow, or sleet may fall from stratocumulus.

the boundary layer between the stratosphere and the mesosphere at about 50 to 55 kilometers (31 to 34 miles).

a layer of the Earth’s atmosphere, between the troposphere and mesosphere, that is stratified in temperature such that cooler layers are closer to the Earth’s surface, and warmer layers are higher up (opposite the pattern of the troposphere near the Earth’s surface); situated between about 10 to 50 kilometers (6 to 31 miles) in altitude above the surface of the moderate latitudes; at the poles, it starts at about 8 km in altitude; composition is basically the same as that of the lower atmosphere, with the addition of ozone.

a principal low-level cloud type (cloud genus) in the form of a low-altitude, light to dark gray cloud layer with a rather uniform base; generally diffuse and dull; this cloud formation has little structure and looks like fog, except that it is above the ground, stratus does not usually produce precipitation, but when it does occur, it is in the form of minute particles, such as drizzle, ice crystals, or fine snow grains.

a peatland with roughly parallel narrow ridges of peat dominated by fenland vegetation interspersed with slight depressions, many of which contain shallow pools.

a long narrow area of pack ice, about 1 kilometer (0.6 mile) or less in width, usually composed of small fragments detatched from the main mass of ice, and run together under the influence of wind or current.

permafrost beneath a glacier.

a layer or body of unfrozen ground beneath a glacier in an area with permafrost.

the transition of a substance from the solid phase directly to the vapor phase, or vice versa, without passing through an intermediate liquid phase.

ice formed by reverse sublimation of water vapour on cold surfaces.

water occurring in the noncryotic ground below the permafrost.

a glacier whose temperature regime is between polar and temperate; usually predominantly below freezing, but could experience extensive summer melt.

permafrost occurring beneath the sea bottom.

a layer or body of unfrozen ground beneath the seabottom, and forming part of the subsea permafrost.

the permanent ice zone that remains in summer after all melting has occurred.

ablation hollows that develop during intense sunshine.

dark spot on the sun, with cooler-than-average temperatures and strong magnetic activity

the condition when a liquid remains in the liquid state even through its temperature is below its freezing point.

cooling of a liquid to a temperature below its freezing point, without causing solidification.

the condition which occurs in the atmosphere when the relative humidity is greater than 100%.

water occurring in unfrozen ground above perennially frozen ground.

a distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which coarser soil particles have vertical or near-vertical orientation.

the cumulative number of degree-days below 0 degrees Celsius for the surface temperature (of the ground, pavement, etc.) during a given time period.

the deposition (sublimation) of ice crystals on a surface which occurs when the temperature of the surface is colder than the air above and colder than the frost point of that air.

a meteorological observation made on the earth's surface, in contrast with an upper-air observation.

the ambient temperature indicated by a thermometer exposed to the air but sheltered from direct solar radiation, or placed in an instrument shelter 1.5 - 2.0 meters (5.0 - 6.6 feet) above ground; also called air temperature.

wind blowing near the earth's surface; it is measured, by convention, at a height of 10 meters (33 feet) above ground in an area where the distance between the anemometer and any obstruction is at least 10 times the height of the obstruction.

a glacier that experiences a dramatic increase in flow rate, 10 to 100 times faster than its normal rate; usually surge events last less than one year and occur periodically, between 15 and 100 years.

a substance dispersed throughout another substance; also called suspended phase.

ground ice developed during the formation of syngenetic permafrost.

an ice wedge developed during the formation of syngenetic permafrost.

permafrost that formed through a rise of the permafrost table during the deposition of additional sediment or other earth material on the ground surface.

the study of the synoptic observation data plotted on synoptic charts aimed at analysis of the atmospheric disturbances (for example, fronts, cyclones, and anticyclones).

a weather chart reflecting the state of the atmosphere over a large area at a given moment.

a code approved by the World Meteorological Organization, by which meteorological elements observed at the earth's surface at synoptic times are encoded in groups of five figures and transmitted internationally through the GTS (Global Telecommunications System).

hour (UTC - Coordinated Universal Time) determined by