The Effect of Screening Charge Transport on Electrification and Precipitation Processes in Thunderclouds

Abstract

Considering the growth of hydrometeors along with electrical state and interaction among all categories of particles in thunderclouds, the effect of screening charge transport on electric field, precipitation intensity, charge, size and fall velocity of hydrometeors, has been studied. The study reveals that screening charge transport increases the growth rates of electric fields and decreases the precipitation intensities. The calculations show that thunderclouds containing low precipitation intensities, can also generate high electric fields within appropriate time intervals.

Some theoretical aspects of electric field and precipitation growth in a finite thundercloud

“…In the present study the particles are divided into five (N = 5) size intervals i.e. R1,R2,Ra,R¢ and R5 (Ziv and Levin 1974;Singh et al 1985). The first interval R1 denotes cloud particles while the remaining intervals represent precipitation particles.…”

“…Jd (t) and Js (t) are discharge and screening charge current densities at instant t, respectively. Discharge current density can be expressed as (Levin and Ziv 1974;Singh et al 1985) Ja (t) = (10-8/3) [exp (6.7 x 10-6 E (t)) -exp (6.7 x 10-6 Eo )-],…”

“…The equations describing the variations of the particles sizes and charges are given by (Ziv and Levin 1974;Singh et al 1985):…”

“…Ziv and Levin (1974) and Levin et al (1977) demonstrated a direct coupling between the precipitation and electrical development in thunderclouds. The growth of hydrometeors and the charge separation in thunderclouds have been reported as related processes (Holmes et a11980;Toshikatsu 1980;Singh et al 1985). Experimental evidence for the accretion of supercooled water-droplets as hail pellets in the presence of electric field has also been shown by Aufdermaur and Johnson (1972).…”

“…Many mechanisms have been proposed to explain the electrification of thunderclouds and the generation of thunderstorm electricity. (Mason 1972;Paluch and Sartor 1973;Ziv and Levin 1974;Chiu and Klett 1976;Chiu 1978;Mathpal et al 1982;Singh et al 1985). Generally, in earlier theoretical treatments the cloud has been visualized as an infinite parallel plate capacitor.…”