Radar Tests of the Precipitation Hypothesis for Thunderstorm Electrification

The contribution of falling precipitation to thunderstorm electrification is examined from an energy standpoint by means of radar measurements of precipitation. The gravitational power associated with falling precipitation is compared with estimates of the thunderstorm electrical output as a test of a causal relationship between these two quantities. The relative importance of the gravitational and electrical forces acting on precipitation particles is investigated by monitoring the stability of particle vertical motions to lightning-associated changes in electric field. The general absence of abrupt particle velocity changes is difficult to reconcile with the gravitational power determinations in electrically active storms unless the electrical energy contribution from convective motions is substantial.