Roles of dust or object perturbing an electric cusp in electric reconnection and consequent electric discharge or lightning

Abstract

On the basis of new electrohydrodynamics (EHD) with the equation of electric field transport, it has been shown that any perturbation exerted on an electric cusp can cause the local singularities, leading to electric field line merging-reconnection. Such a perturbation can usually be done by dust or object, conducting or dielectric. If the background environment is a collisional neutral gas with atmospheric pressure and a local frozen-in field strength at the surface of dust or object is high enouh, a local breakdown or discharge produces an ionising EHD shock along the field line in the form of leader, forming a discharge channel, and eventually causing electric discharge or lightning. Although such a cusp model has already proved relevant to a couple of phenomena, such as rocket-triggered lightning, EHD flow acceleration or shock generation, and ball lightning, new observational evidence supporting this model is introduced which has been obtained from natural lightning observations during winter thunderstorms in a coastal region of the Sea of Japan. Further, it is newly suggested that a fluid vortex breakdown or merging point observed from tornadic thunderstorms such as Minneapolis, Minnesota, tornado might be a manifestation of joint effects of dust-related electric reconnection and self-organization to a coalescence of fluid vortex breakdown or merging point and electric field line merging-reconnection point. Finally, a new interpretation is put forward for the production of a special kind of materials such as Chondrules, CAI-rims, or oxygen isotope anomalies in meteorites that is likely to be consequences of dust heating by electric reconnection in protoplanetary disks. It is thus claimed that dust or object plays multiple crucial roles in whole processes of electric field line merging-reconnection, leader or discharge channel formation, electric or lightning discharge, and rapid heating of dust itself.