Short Notes: On Depth Hoar and the Strength of Snow

It has long been known that a temperature gradient in the snowpack, when temperatures are less than 0°C, can metamorphose the snow to produce a fragile euhedral crystalline end product called “depth hoar" which is considered to be responsible for snowpack collapse and climax avalanches. The wave of metamorphism advancing through anhedral snow converts it, first to subhedral, and finally to euhedral depth hoar. Our field observations, which are at the moment supported by laboratory evidence, reveal that the zone of minimum snow strength in the gradient metamorphic layer is associated with the intermediate subhedral phase rather than with the euhedral end product.