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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.

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