A theoretical study of progressive developments in rain- drop size distribution and other characteristics in rain showers from 'warm' convective type clouds

Abstract

A study, on a theoretical basis, of the expected size distribution of raindrops and rainfall intensity at various phases of rain showers from an overhead large cumulus cloud of 'warm' type has been made, assuming that each raindrop is the result of growth on a 'giant' sea-salt nucleus, and that droplet growth beyond a certain sizes is due mainly to coalescence following collisions between cloud droplets. The study, based on assumptions of plausible physical conditions in a cloud in regard to (a) concentration and size distribution of' giant sea-salt nuclei in air, (b) mean cloud liquid water content and (c) updraft rate and its variations with time, brings out features which are in general conformity with what are observed in rain from warm convective type clouds, and provides some corroboration of the present accepted theory of coalescence growth of raindrops, and of the salt-nucleus hypothesis of rain formation in such clouds.