Definitions for "Firn"
Névé on a glacier that survives the year's ablation season. With time much of the firn is transformed into glacial ice.
The granular edge of snowfield that has remained frozen through the summer but is not yet considered glacial.
A transitional stage between snow crystals and ice where the increasing weight of the overlying material causes the snow crystals to settle, deform and recrystallize, leading to an increase in unit density. Further increases in the overburden causes the firn to continue to increase in density as the air spaces in the crystals are reduced by mechanical packing and plastic deformation. The interconnected air passages are sealed off into individual air bubbles at a density of about 0.83 kg/m3, marking the transition into ice.
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