National Snow and Ice Data Center

snow cover

(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.

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snow density

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

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snow depth

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

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snow extent

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

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snow flurry

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

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snow grains

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.

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snow layer

a layer of ice crystals with similar size and shape.

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snow line

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.

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snow load

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

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snow patch

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

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snow pellets

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.

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snow roller

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

snow squall

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

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snow water equivalent

the water content obtained from melting.

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snow worm

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.

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glaciers

snowblink

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.

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snowbursts

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

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snowdrift

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

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snowdrift glacier

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

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glaciers

snowfall

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

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snowflake

a cluster of ice crystals that falls from a cloud.

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snowmelt

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

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snowpack

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

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snowstorm

strong wind with snow.

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soil wedge

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

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solar radiation

the total electromagnetic radiation emitted by the sun.

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solifluction

slow downslope flow of saturated unfrozen earth materials.

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solifluction apron

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

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solifluction features

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

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solifluction lobe

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.

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solifluction sheet

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

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solifluction terrace

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

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solstice

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.

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sorted circle

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.

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sorted net

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.

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