Ice crystals grown from vapor onto an orientated substrate: application to snow depth-hoar development and gas inclusions in lake ice

Abstract

AbstractA laboratory experiment was conducted in which new ice crystals were nucleated from the vapor phase onto large existing ice crystals obtained from Antarctic lake ice. Flat, smooth ice-crystal surfaces were prepared, with c axes oriented either vertically or horizontally. When these were subjected to a supersaturated vapor environment, multiple individual crystals nucleated onto the substrates adopting the same crystallographic orientation as the parent. A dominant grain-growth scenario for kinetic-growth metamorphism in snow, which in some ways is analogous to the oriented morphologies in lake ice, is hypothesized. In the lake-ice-growth scenario, optimally oriented crystals will grow at the expense of those less preferentially positioned.The proposed dominant grain-growth theory for snow is in agreement with the observed decrease in the number of grains and the proximal similarity of crystal habit in kinetic-growth metamorphism in snow. Similarly, kinetic crystal growth on the interior of gas inclusions in Antarctic lake ice will also acquire the crystallographic orientation of the substrate ice. These small-faceted interior crystals significantly influence light scattering and penetration in the lake-ice cover.