Effect of Electric Charge on Collisions between Cloud Droplets

Abstract

simple model is presented for the calculation of the effect of electric charges on the collision and coalescence of cloud droplets, a topic that is of importance for coalescence-induced natural rainfall and for the possible effectiveness of techniques for increasing rainfall by injection of ions into the atmosphere. Whereas electric charges of opposite sign enhance the collision efficiency of cloud droplets, the effect when all droplets bear charges of the same sign depends strongly upon the droplet sizes and separations and upon the ratio of charges on each of a droplet pair. The conditions under which coalescence is increased exist for only a very small fraction of actual cloud structures.