The effect of wind on heat transfer in snow

Abstract

Heat flux in snow is found to be a strong function of wind speed. Strong thermal gradients in surface snow layers are observed only during light or calm winds. This finding is not unexpected when it is noted that typical fresh snow has a density of 0.1 to 0.2 gm·cm −3 and is, therefore, largely (90 to 80%) air-filled pore space in a fragile ice matrix. Observed heat flux density in snow during calm winds is in good agreement with the theory of molecular transfer in still air and ice. An expression for the thermal conductivity of snow in still air as a function of path length, age and density is presented. Order of magnitude increases in thermal diffusivity were observed during strong winds, which implies a forcing process or “pumping” action induced by gust or eddy elements in the atmosphere. This is consistent with similar effects in soil reported in the literature. Approximate quantification of the total heat transfer process is possible, but a distinction between sensible and latent heat flux was not possible in this experiment. Heat and mass transfer in snow is important in the analysis of radionuclide pathways through the environment. This work is in support of the Canadian nuclear fuel waste management program.