Mechanism of lightning initiation without electrodes and at low breakdown fields

Determine the physical mechanism that accounts for lightning initiation and discharge in thunderclouds in the absence of electrodes and at electric field strengths substantially below classical breakdown thresholds, clarifying how streamer formation and channel development proceed under these conditions.

Background

The paper reviews observational and theoretical challenges in explaining lightning initiation. A specific difficulty highlighted is that natural lightning occurs without conventional electrodes and often at electric field strengths lower than laboratory breakdown thresholds. Prior studies examining the role of metastable oxygen and nitrogen molecules suggest their influence is insufficient to initiate lightning streamers, and time-domain simulations of preliminary breakdown have been conducted in simplified geometries, yet a comprehensive mechanism remains unsettled.

The authors propose a new mechanism involving temporary metallic bonding and resonance-percolation pathways in thunderclouds, but explicitly note that the traditional problem of understanding initiation under low-field, electrode-free conditions is not yet closed.

References

Another difficulty in explaining the processes of lightning discharges is associated with the absence of electrodes and with low breakdown fields. Despite the increased interest in such studies, this problem cannot yet be considered to be closed.

— New Physical Mechanism for Lightning  (2402.04096 - Artekha et al., 2024) in Section 1, Introduction