Features of negative and positive leaders of negative CG lightning according to simultaneous records of current, E-field, luminosity and high-speed videos

Abstract

Lightning measurements performed recently at Morro do Cachimbo Station, Brazil, are considered in the discussion in order to consolidate previous findings regarding the main propagation features of negative and positive leaders. The stepping mechanism of negative leaders was observed at the station for the first time. Common and unusual propagation features of such leaders were presented. Regarding positive leaders, it was demonstrated that sustained positive upward connecting leaders in negative downward lightning initiates after a 4-A continuous current threshold is exceeded. It was also shown that propagating continuously is a common feature of positive upward leaders in general. Based on these findings, a model of positive upward connecting leaders was presented and discussed.