How do evaporation and condensation make snow grains rounder and denser?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

glacier Perito Moreno Glacier, Los Glaciares National Park, Argentina.

The process of evaporation and condensation is a key factor in the transformation of snow into glacier ice.

In a deposited snowpack, the intricate, sharp-pointed shapes of initial snow crystals are unstable. Molecules tend to evaporate from these high-curvature points and condense into the hollows of the ice grains. This redistribution of mass causes the grains to become rounder, allowing them to fit more closely together. As these grains pack more tightly, the overall density of the snowpack increases.1

This process can continue as touching grains develop "necks" of ice—a process known as sintering—which further connects the grains and contributes to the densification of the mass. These changes occur more rapidly at temperatures near the melting point and more slowly in colder conditions.1