An investigation of the effect of electrical charges on the collision efficiency of cloud drops

Theoretical investigations of the effects of drop electric charges on the gravitational coagulation process of drops of significantly varying sizes, while increasing their charge to the limiting values, are summarized. The intermediate Reynolds numbers ranging from 10 to 60, which correspond to fall velocities of the collector drops with radii ranging from 100 to 250 microns are studied because of the lack of data on the strongly charged drop growth velocity due to coagulation with neutral and charged droplets of radii from 1 to 20 microns. The drop size and charge range is the range in which particle growth occurs in clouds including thunderstorm clouds. Modification methods of warm clouds intended for precipitation growth enhancement are developed also in this range.