Modification of some microphysical properties in the highly electrified regions of thundercloud

Abstract

Changes in the velocity of charged cloud and precipitation particles due to large electrical forces acting on them, cause them to accumulate in small regions of intense electrification in thunderclouds. These accumulations of particles can modify the microphysical properties of such regions. Here we have calculated the changes in size-distribution of the cloud and precipitation particles, the rain water content and the rainfall intensity in these regions for different values of electric field, drop charges and updraft speed. Modified size-distributions of precipitation particles show a general increase in concentrations of large particles and a maxima for particle sizes whose velocity under the influence of gravitational and electrical forces is equal and opposite to the updraft speed. Rain water content increases and the rainfall generally decreases in such regions. Size-range of the particles contributing the maximum to the rain water content is higher in higher electric fields and for large particle charges. However, size-range of particles contribute the maximum to the rainfall intensity. For any appreciable change in size-distribution of cloud particles, the electric field and the particle charges have to be very large. In view of the above results, it is suggested that levitation of the particles in regions of intense electrification may cause or contribute to the rain gush phenomenon in thunderclouds.