On the processes leading to different modes of charge transfer in negative flashes according to fast videos and correlated records of current and electric field

Abstract

This work discusses the processes involved in different modes of charge transfer in negative lightning flashes, taking as reference video-records obtained with a fast camera and records of current and close electric-field measured at Morro do Cachimbo Station. The data of two downward and one upward negative flashes are explored for considering the features of these processes and for supporting their interpretation, based on the bidirectional and bipolar leader approach. The processes comprise three sequences (stepped leader - first return stroke, dart leader - subsequent return stroke, dart-stepped leader - subsequent return stroke), in addition to the initial continuous current in upward lightning, return strokes following it, continuing current and M-components, the latter observed superimposed on both the continuing current and the tail of return stroke currents. An unreported process of charge transfer, consisting of the reignition of the dissipating leader of an upward lightning from the ground to the cloud is analyzed as well.