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stone earth circle

a type of nonsorted circle developed in gravelly materials.

stone garland

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

stone-banked (solifluction) lobe

a solifluction lobe with a stony front.

stone-banked (solifluction) terrace

a solifluction terrace with a stony front.

strand crack

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.

string fen

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.

subglacial permafrost

permafrost beneath a glacier.

subglacial talik

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.

sublimation ice

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

subpermafrost water

water occurring in the noncryotic ground below the permafrost.

subpolar glacier

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

subsea permafrost

permafrost occurring beneath the sea bottom.

subsea talik

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


Provides the ability to narrow your search by providing specific temporal ranges and or spatial coordinates.

summer minimum extent

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

sun cups

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%.

supraglacial moraine

dust and/or rock that rides the surface of a glacier.


suprapermafrost water

water occurring in unfrozen ground above perennially frozen ground.

surface cryogenic fabric

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

surface freezing index

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

surface hoar

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.


surface observation

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

surface temperature

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.

surface thawing index

the cumulative number of degree-days above 0°C for the surface temperature (of the ground, pavement, etc.) during a given period.

surface wind

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.

surging glacier

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.
In 1941, Hole-in-the-Wall Glacier surged, also knocking over trees during its advance. (Photo courtesy of the World Data Center for Glaciology, Boulder, CO. Photo probably taken by W.O. Field.)