Ion transport to cloud droplets by diffusion and conduction, and the resulting droplet charge distribution

Abstract

The influence of an electric field on the diffusion of ions to cloud droplets is calculated by the method of matched asymptotic expansions. The model assumes the droplet suspension is disperse and stationary in the ionic gas, ignores space charge and selective adsorption of ions, and regards each droplet as a perfectly conducting sphere. The resulting mean charge and dispersion of an assumed normal distribution of charge among a set of equal- sized droplets are determined. It is found that the dispersion increases with electric field strength, as does the mean charge for a fixed ratio of polar conductivities.