sea ice

lead shore

a lead that forms between drift ice and the coast.


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.
Lead that developed through the middle of an Arctic camp site. (Photo courtesy of Don Perovich, U.S. Army Cold Regions Research and Engineering Laboratory.)

latent heat polynya

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).


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.

internal ice stress

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.


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


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.

ice skylight

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.

ice rind

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.

ice limit

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


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