Grain coarsening of snow saturated with solution

Abstract

The effect of impurities on grain coarsening of water-saturated snow was studied by saturating fine grained snow with solutions of NaCl, HCl, glucose and dextran of varying concentration from zero up to 2 moles per kilogram of water. Over the observed time scale of up to 1, 000 hours, mean grain volume increased linearly with time as with pure water, but the rate of increase was slowed in comparison to that for pure water, depending on the type of impurity and its concentration. For concentrations less than about 0.01 mole per kilogram, there was negligible departure from the pure water rate, but at the highest concentration rate was slowed by a factor of 1/32. Based on a model of texture change caused by freezing and melting on particle surfaces and analyses of the diffusion of heat and solute through the interstitial solution, the retardation of grain growth rate is determined by the ratio of freezing point depression and impurity diffusion coefficient of the solution, and the experimental data are found to be consistent with the theoretical predictions.