How do glaciers form?

Glacial ice is composed of ice crystals, snow, air, water and sediments. Glaciers are mainly formed from compressed snow, with only a small proportion due to freezing of water. Glaciers form when more snow accumulates over the year than melts during the summer. As layers of snow accumulate, the buried snow grains become more and more tightly packed and are converted to firn which subsequently metamorphoses to glacial ice as the firn recrystallizes. This process takes place in the accumulation area at the higher altitudes. The thick mass of ice deforms under its own weight and flows downstream like dough or molten metal. The ice flows downhill towards the ablation area where melting exceeds the accumulation of snow over the year.

 

 Conversion of snow to glacial ice.

Conversion of snow to glacial ice.