Some research problems in snow mechanics and thermodynamics

The causes for discrepancies in the presently reported values for physical constants of snow are discussed. Snow strength is influenced by present and past temperatures and the frequency of temperature cycles. Some problems in snow mechanics are analogous to those in soils, but snow, particularly near the freezing point, may react oppositely for a given force. Releasing pressure on a soil increases its plasticity; releasing pressure on snow, near the ice point reduces plasticity by causing free water between the grains to freeze. The derivation of a traction index from the mechanical properties of snow or the forecastable degree of metamorphism is complicated by the inconsistency of the frictional resistance of the snow surface. Theories based on the narrow temperature range which separates the liquid, vapor, and solid phases of snow to account for the low but variable coefficient of friction for snow are discussed.