Infrared images of bidirectional leaders produced by the cloud of charged water droplets

Abstract

Detailed infrared (2.7-5.5 μm) images of bidirectional leaders produced by the cloud of small (typical radius of 0.5 μm), positively charged water droplets are presented. The leader was composed of the downward extending positive part and the upward extending negative part, these two parts (both branched, although in different ways) being connected by the single-channel middle part. The downward extending part included the tortuous positive leader channel (similar to its upward extending counterpart observed when the cloud polarity was negative) that was often accompanied by much less tortuous but often equally bright downward extending plasma formations of unknown nature. Very faint positive streamer zone was also observed. Either the positive leader channel or the unusual plasma formation (UPF) can come in contact with the grounded plane. The upward extending part is associated with a large network of faint channels, mostly fanning out of the upper part of the usually much brighter leader channel and apparently pervading the entire upper part of the cloud. Some of those faint channels could be unusually long and bright negative streamers, while others could be similar to UPFs. The IR luminosity along the brightest part of the bidirectional leader channel is often nonuniform. Some variations in channel brightness are localized and suggest the involvement of space leader-type processes at multiple positions along the channel, changes in channel orientation, or variations in channel radius.

Initiation and propagation of cloud-to-ground lightning observed with a high-speed video camera

“…Leaving aside bidirectional leaders originating from metallic objects171819, there appear to be four main scenarios for the formation of bidirectional leaders: (1) initiation of lightning in the cloud [present study; see also Kostinskiy et al 9202…”

Observations of the connection of positive and negative leaders in meter‐scale electric discharges generated by clouds of negatively charged water droplets

“…The experimental setup is shown in Figure 1 of Kostinskiy et al . []. The jet‐shaped cloud of negatively charged water droplets was formed above a grounded metal plane.…”

“…A more detailed description of the overall experimental setup can be found in Kostinskiy et al . [].…”

“…Kostinskiy et al . [] have obtained detailed infrared images of bidirectional leaders produced by the cloud of positively charged water droplets. The leader was composed of a downward extending positive part and an upward extending negative part, these two parts (both branched) being connected by a single‐channel middle part.…”

Numerical Simulation of Stepping and Branching Processes in Negative Lightning Leaders

“…In this appendix, we discuss the method of feeding of (supplying negative charge to) the growing discharge tree in our model. Lightning leaders prior to their connection to the ground, have both positive and negative parts (see, e.g., Kostinskiy et al, 2015;van der Velde & Montanyà, 2013). The charge redistribution between those two parts occurs in such a way that the positive part acts as a source of negative charge for the negative one and vice versa.…”