The snow cover is the entire snowfall deposited over a period, which varies widely in space and time. The individual layers differ in consolidation, density and plasticity and can often be detected with the naked eye. The temperature conditions in snow cover are extremely important for the quality of the snow and therefore the stability of the snow cover. Temperatures on the ground are around freezing point but the temperature on the surface of the snow is determined by the atmospheric conditions. Daily fluctuations only affect the top 20-30 cm of the snowpack. Consequently there is a temperature gradient in the snowpack which contributes to metamorphosis of the snow.