SOME OBSERVATIONS ON THE DENSIFICATION OF ALPINE SNOW COVERS

Through pit measurements on selected deep seasonal snow covers, observations have been made on the densification rates of dry snows. The variation between rates has been compared with such physical characteristics of the snow as temperature, grain size, and loading rate. The rate of densification does not appear to be affected by temperature in the -1 to -10 degrees C range but it is inversely proportional to grain size and sensitive to rates of loading during the formative stage of any particular snow layer. Values of compressive viscosity vary from 100,000 to 10 to the 9th power gm/sq cm per second which is an order of magnitude less than the lowest values for polar snow. Plots of specific volume against overburden reveal a sharp discontinuity at a specific volume of about 3.0 cu cm/gm. The persistence of this discontinuity from location to location indicates that it may reflect a real phenomenon. It is suggested that it may be accounted for by extremely high strain rates at low densities. (Author)