Report of the committee on evaporation and transpiration, 1951–1952

Abstract

The Committee's report for 1951–52 consists of items dealing with evapotranspiration as influenced by soil‐plant‐climatic interaction and with methods of determining water loss.The Snow, Ice, and Permafrost Research Establishment is highly interested in a little recognized evaporation problem in snow‐covered areas. This is the “production of depth hoar within the snow blanket.” Investigations at Fort Churchill, Manitoba, and adjacent areas in the Arctic in February and March, 1951, indicate that the production of massive amounts of depth hoar is the result of a soil‐plant‐climate interaction. Depth hoar may consist of a few inches to several feet of a loose, fragile horizon of crystals which have little or no resemblance to the more classic forms of snow crystals. The depth hoar crystals lack cohesiveness, and when such horizons exist near the snow surface, the supporting capacity for troops, vehicles, and planes is greatly reduced. This very deceptive hazard is difficult to recognize.