Laboratory measurements of charge separation in low liquid watercontent conditions and low impact velocity

E.E. ÁVILA; R.A. LIGHEZZOLO; N.E. CASTELLANO; R.G. PEREYRA; R.E. BÜRGESSER

JOURNAL OF GEOPHYSICAL RESEARCH

AMER GEOPHYSICAL UNION

Año: 2013 p. 1 - 8

0148-0227

A laboratory investigation of the electric charge separated in collisions between vapor-grown ice crystals and a target growing by riming is presented in this work, with the goal of studying the performance of the noninductive mechanism under microphysical conditions similar to some of those which occur in the stratiform regions of the mesoscale convective systems. A series of experiments were conducted by using a target of 2mm in diameter, for ambient temperatures between 7°C and 13°C, effective liquid water content between 0.05 and 0.5 gm3, and air speeds between 1 and 3ms1. Charge diagrams of the sign of the electric charge transfer on the rimer as a function of the ambient temperature and the effective liquid water content for each velocity are presented. The results show that the riming target charges positive for temperatures above 10°C. For temperatures below 10°C, the charging is positive for high liquid water content and negative for low liquid water content. The magnitude of the charge transfer per collision under the studied conditions ranges from 0.01 to 0.2 fC.