SOME QUALITATIVE RESULTS ON THE ELECTRIFICATION OF SNOW

Abstract

This paper reports on observations of the electrical charges on falling and drifting snow, and gives the results of laboratory experiments designed to determine the relative importance of possible charge-producing mechanisms in the atmosphere when snow and ice crystals are present. These mechanisms include impacts of snow particles on one another, melting of snow as it falls, and condensation of water vapor and formation of rime on falling snow. Apparently a large fraction of the snowflakes falling during the cold part of the winter in Saskatchewan has a charge less than 2 × 10−4 e.s.u. per flake. During blizzards the snow particles blowing along or just above the hard surface of the drifted snow carry a net negative charge and the air at the 1 m. level has positive space charge densities that are from 10 to 100 times the normal, positive space charge density. Very large charge separations can occur when a snow surface is eroded by an air blast and when snow is blown against snow and metal surfaces, a resultant negative charge appearing on the heavier particles and the corresponding positive charge on either very small ice particles or ions This charge-producing mechanism is most effective at high air velocities and at low temperatures The melting of newly fallen snow under conditions favorable to the escape of air bubbles does not show a charge separation. Condensation of water vapor and formation of rime on snow surfaces result in only very small charge separations for the conditions readily obtained in laboratory experiments