Streamer initiation from column hydrometeor at weak ambient electric field

Abstract

In this work, an isolated dielectric column with rigid interface is used to demonstrate the process of streamer initiation from a real hydrometeor in cloud at weak ambient field. For a hydrometeor made of water or ice, it can be approximated as a conductor in electrostatic field. A system with two identical conducting spheres electrically connected by a thin wire has similar electric field distribution as a conducting column, which is adopted to find the electric field of the polarized column conductor in an ambient field. The modeling results show that electric field is significantly enhanced around the tips of the hydrometeor. At a positive streamer can be initiated from the positive tip of the hydrometeor, and no negative streamer is generated at the other tip. Although the main features of the positive streamer are similar with those reported previously on the positive streamer initiated from an ionization column, significant differences exist because the present model of the hydrometeor has a rigid surface. Peak electric field undergoes a slight decrease before it begins increasing, and both peak electric field and electron density have not reached steady values during our simulation time interval. The simulation results also confirm the finding from the ionization column model that when the hydrometeor length is longer, the streamer discharge can be initiated at a lower electric field. The charge accumulation on the hydrometeor and the accumulation rate show that the electron flux on the surface of the hydrometeor undergoes a complex process, which needs to be studied in the future.