Large-Scale Charge Separation in Thunderclouds

Currently available evidence for the mechanisms thought to be responsible for large-scale charge separation in thunderclouds is reviewed. The evidence suggests that electrically charged precipitation particles are basic to the electrification process but that convective motions are essential in accounting for the electrical energy of active thunderstorms. The relative contributions of air and particle motions remain largely unquantified, and the physical origins of thundercloud electrification have yet to be established.