Snow, an Intriguing, Complex, and Changeable Solid

Abstract

This chapter provides basics of snow structure and topology. As snow is a complex arrangement of ice crystals, themselves found in oodles of geometrical shapes, sizes, and formation mechanisms, we essentially focus on those that are more directly involved in avalanche release. Three snow peculiarities are also outlined. Snow being made of ice, it inherits its particular propensity to melt under external pressure. Since snow cover results from accumulation of snowflakes, it may be considered as a granular material, with quite original properties due to the unusually large grain surface vs volume ratio, and to their related tendency to change shapes and to heal. Snow being also a mixture of ice, air, and water, the topological concept of percolation is of interest to deal with stress distribution in the snow cover, and is briefly discussed.