Thundercloud Electrification: Cloud Growth and Electrical Development

Abstract

A time-dependent numerical model is used to simulate the growth of the electric field in thunderclouds by the polarization mechanism, including both the growth of hydrometeors and the growth of the electric charge centers. The results demonstrate a direct coupling between the hydrometeor growth and the electric field. Different types of cloud are discussed with reference to their electrical behavior. It is found that clouds containing large ice particles and small supercooled water drops and fully glaciated clouds can produce electric fields sufficient for lightning to occur. Electrical forces in the clouds tend to slow down the relative fall velocities of the precipitation particles, and reduce their interaction rate. The net effect is a slowing down of the growth of the hydrometeors and the rate of buildup of the electric field.