Well-sintered snow was examined in a scanning electron microscope. This revealed a structure that protruded into the pore space along ice grain boundaries, and was termed a grain-boundary ridge. This was attributed to grain-boundary diffusion with mass migrating, from the center of contact of the crystals, to the surface of the bond. Because mass tended to sublimate from sharp features and towards lower-curvature surfaces, via vapor diffusion, ridges developed by grain-boundary diffusion could easily give up mass to surrounding ice surfaces. Based upon the observed geometry, a mass balance between vapor and grain-boundary diffusion was derived. This indicated that grain-boundary diffusion could play a much more significant role than was generally thought.

Grain Boundary Ridge on Sintered Bonds between Ice Crystals. E.E.Adams, D.A.Miller, R.L.Brown: Journal of Applied Physics, 2001, 90[11], 5782-5