Subnivean

Subnivean climate refers to the zone in and underneath the snow pack. From the Latin for "under" (sub) and "snow" (nives). This is the environment of many animals that remain active during the winter. This zone provides protection from predators and insulation from the elements. The subnivean climate is formed by three different types of snow metamorphosis: destructive metamorphosis, which begins when snow falls; constructive metamorphosis, the movement of water vapor to the surface of the snow pack; and melt metamorphosis, the melting/sublimation of snow to water vapor and its refreezing in the snow pack. These three types of metamorphosis transform individual snowflakes into ice crystals and create spaces under the snow where small animals can move.