HEAT BALANCE STUDIES DURING AN ICE-FOG PERIOD IN FAIRBANKS, ALASKA

Abstract

Ice fog, which is in a way similar to a dense cirrostratus cloud near the surface, occurs in Fairbanks when the temperature drops below ?35°C. The heat balance of two stations, one below the ice fog in the valley and the other one on Birch Hill above the ice fog, are compared for the longest cold spell in winter 1966/67. The valley station shows a relatively small radiative loss of 47 cal cm?2 day?1, as the ice fog shelters the surface against a highly negative long-wave radiation balance. The energy for compensation of this loss comes mostly (25 cal cm?2 day?1) out of the soil. On Birch Hill the radiative loss (124 cal cm?2 day?1) is nearly three times larger, mostly due to the smaller amount of the incoming long-wave radiation, and here the sensible heat flux (102 cal cm?2 day?1) provides most of the energy.