Sublimation as a geomorphic process: A review

Abstract

Ice and snow sublimation is a naturally occurring process in which the solid ice changes state to become a vapour without passing through the usual liquid stage. The sublimation of blowing snow can be critical in areas which rely on melting snow as an important source of moisture. In blowing snow, the sublimation process is influenced by air temperature, relative humidity, wind speed, net radiation and particle surface area. When pore ice sublimation occurs in an ice/sediment mixture, the process is complicated by the presence of the particles of sediment. The sublimation of frozen moisture from sediments has implications for dust production, for human safety in permafrost tunnels, and for the aeolian movement of sediments in cold environments. A limited number of studies have considered sublimation from frozen sediments and a very few of these have been done under field conditions. The variables of air temperature, relative humidity, sediment moisture content and wind speed influence the amount and rate of pore ice sublimation, but there is some disagreement as to the relative importance of these variables.

Ice sublimation as a geomorphic process: A planetary perspective

“…In contrast outdoor experiments performed on pure ice surfaces, tended to emphasize the importance of wind as a transport agent for the water molecules which had been sublimated from the surface (Branton et al, 1972). Experimental data show that sublimation influences the transport of sand under subzero conditions by reducing the binding effectiveness of the pore ice (Law and Van Dijk, 1994;Van Dijk and Law, 1995). The loosened grains can then be entrained by the wind and serve to enhance movement by the abrasion of frozen particles downwind.…”

Rapid changes of the ice mass configuration in the dynamic Diablotins ice cave – Fribourg Prealps, Switzerland

“…Moreover sublimation seems to be more efficient between −1 and −4 • C. Below −4 • C, the rate will decrease to become very low at −12 • C. A more intense airflow velocity (depending on the thermal gradient between the external air and cave air temperatures) will also increase the rate of sublimation, by raising the rate of heat exchange of water molecules between the rock and ice surface, and the air. Nevertheless the magnitude of these effects is widely discussed (Law and vanDijk, 1994). Anyway all experiments showed that the rate of sublimation increase by (1) decreasing relative humidity of air, (2) rise in air temperature until the freezing point and (3) increasing wind velocity.…”

“…4h) or by the presence of a fine dust layer on the floor. Law and vanDijk (1994) interpreted the existence of this thin layer of sediments as a result of the sublimation of the frozen surface of the cave walls. The apparently counter-intuitive relationship between cave air temperature and relative humidity in the different parts of the ice cave could also be interpreted as an evidence of very efficient sublimation events in winter.…”

“…But which variables could best explain this process observed in wintertime? Law and vanDijk (1994) made a review of sublimation as a geomorphic process on frozen sediments, ice and snow, and discussed the relative importance of changes in relative humidity, air temperature and wind velocity. Some experiments showed that a decrease in relative humidity from 90% to 80% had doubled the rate of sublimation (Law and vanDijk 1994).…”

“…Law and vanDijk (1994) made a review of sublimation as a geomorphic process on frozen sediments, ice and snow, and discussed the relative importance of changes in relative humidity, air temperature and wind velocity. Some experiments showed that a decrease in relative humidity from 90% to 80% had doubled the rate of sublimation (Law and vanDijk 1994). Moreover sublimation seems to be more efficient between −1 and −4 • C. Below −4 • C, the rate will decrease to become very low at −12 • C. A more intense airflow velocity (depending on the thermal gradient between the external air and cave air temperatures) will also increase the rate of sublimation, by raising the rate of heat exchange of water molecules between the rock and ice surface, and the air.…”