Comment on 'Grain boundary ridge on sintered bonds between ice crystals' (J. Appl. Phys., 90, 5782 (2001))

Ridges have been observed at the bonds between sintering snow grains. Images collected using the scanning electron microscope (SEM) and x-ray analysis of Antarctic snow are presented. These indicate the ridges are composed from soluble impurity and not ice or water as previously suggested. The ridges can be explained by the coagulation of soluble impurities distributed either at the grain boundaries or on the grain surface. Coagulation is most likely to occur as a result of sublimation during the preparation of the snow specimens for SEM examination, however, they could also form under specific temperature conditions in the snow pack. Consequently, a theory of grain boundary diffusion is not required to explain the presence of ridges at snow bonds.