MEASUREMENTS OF THE SIZE AND ELECTRIFICATION OF DROPLETS IN CUMULIFORM CLOUDS

Abstract

The size and the free electric charge of more than 6000 individual natural cloud droplets have been measured. The measurements were made at a mountain laboratory in southeastern United States in strato-cumulus clouds and in thunderstorm-associated clouds. Stratocumulus clouds with fair-weather electric fields were found to have approximate Gaussian-charge distributions symmetric about zero charge. The magnitude and distribution of charge observed on these non-storm clouds approach values described recently by R. Gunn in his theory of aerosol electrification by the diffusion of environmental light ions. Thundercloud droplets were highly electrified and within given cloud volumes the droplets were charged entirely positive, entirely negative, or fractionally positive and negative.