A Modeling Study of the Impact of Ice Particle Sizes and Relative Velocity on Non-inductive Charge Transfer

摘要

Theoretical investigations on the impact of ice particle sizes and relative velocity on the sign of non-inductive charge transfer during graupel/ice crystal interactions in thunderstorms are performed. The numerical simulations are carried out based on the concept of the Relative Growth Rate Hypothesis that the ice surface growing faster by water vapor diffusion charges positively. Diffusional growth rates of ice crystals and riming graupel particles are calculated for various particle sizes and velocities, and the sign of the non-inductive charging during crystal/graupel collisions is determined. Our study reveals that increasing the graupel particle size favors negative graupel charging, while increasing ice crystal size, or the relative velocity, favors positive graupel charging.