We use the Low Frequency Array (LOFAR) to probe the dynamics of the stepping process of negatively charged plasma channels (negative leaders) in a lightning discharge. We observe that at each step of a leader, multiple pulses of vhf (30-80 MHz) radiation are emitted in short-duration bursts (<10  μs). This is evidence for streamer formation during corona flashes that occur with each leader step, which has not been observed before in natural lightning and it could help explain x-ray emission from lightning leaders, as x rays from laboratory leaders tend to be associated with corona flashes. Surprisingly, we find that the stepping length is very similar to what was observed near the ground, however with a stepping time that is considerably larger, which as yet is not understood. These results will help to improve lightning propagation models, and eventually lightning protection models.

doi.org/10.1103/PhysRevLett.124.105101
Physical Review Letters
Centrum Wiskunde & Informatica, Amsterdam, The Netherlands

Hare, B.M, Scholten, O, Dwyer, J.R, Ebert, U, Nijdam, S, Bonardi, A, … Winchen, T. (2020). Radio emission reveals inner meter-scale structure of negative lightning leader steps. Physical Review Letters, 124(10). doi:10.1103/PhysRevLett.124.105101