MOISTURE EXCHANGE BETWEEN THE ATMOSPHERE AND ALPINE SNOW SURFACES UNDER SUMMER CONDITIONS (Preliminary Results)

Abstract

In order to determine how much of the summer ablation of alpine snowfields was caused by evaporation, known quantities of snow were exposed to the atmosphere in two types of plastic containers. A net gain of moisture was measured at the snow surface during August 1957. A net loss was measured during the first half of July 1958. The diurnal trend was for condensation at nights, evaporation in mornings, and either evaporation or condensation in the afternoons, depending on weather conditions. Shading the snow reduced melt during daylight hours but increased melt after dark. Poor agreement was found between moisture exchange as computed from Sverdrup's equation and measured values.