2.1.8 Glaciers

Glaciers are semi-permanent, large masses of ice that form when snow accumulates over time, turns to ice, and starts flowing downhill under the pressure of its own weight. In polar and high-altitude alpine regions, glaciers accumulate more snow in the winter than they lose in the summer from melting and sublimation. As more snow accumulates, air spaces collapse, snow grains recrystallize, and the buried layers slowly grow together to form a thickened mass of ice. This dense ice usually looks somewhat blue.

Glacier calving, Johns Hopkins glacier, Glacier Bay, AK, 1991

Glaciers are common at high latitudes and in high-elevation areas of the lower-latitude mountain ranges of the Andes, Rocky Mountains, Alps, and Himalayas.

Global glacier locations of sizes 1-5 km