Scavenging of Atmospheric Particles by Growing Ice Crystals: A Contribution to a Proposed Mechanism

Abstract

The mechanism which attributes to Stefan flow around ice crystals (growing by evaporation of supercooled droplets) their high efficiency in scavenging airborne particles is re-examined. The thermophoretic flow toward evaporating bodies, which should counteract the Stefan flow, dons not appear to have an appreciable effect on the motion of particles around supercooled droplets evaporating in the vicinity of the branches of an ice crystal. The relaxation time of water vapor diffusion fields around condensing or evaporating droplets is much shorter than the thermal relaxation time of the droplets and the ice crystals.