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

shear strength

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.

shore lead

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

short-term strength

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

shortwave radiation

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.
(Photo courtesy of the Antarctic Sea-Ice Processes and Climate program (ASPeCt).)

Siberian high

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.

single-phase thermosyphon

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.

slope failure

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.

slush zone

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.

snow barchan

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

snow board

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

snow bridge

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.

snow core

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.

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.

snow density

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

snow depth

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

snow extent

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

snow flurry

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

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.

snow layer

a layer of ice crystals with similar size and shape.

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.

snow load

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

snow patch

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

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.

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.

snow water equivalent

the water content obtained from melting.

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.