We found a match
Your institution may have rights to this item. Sign in to continue.
- Title
Lightning Initiation From Fast Negative Breakdown is Led by Positive Polarity Dominated Streamers.
- Authors
Huang, Anjing; Cummer, Steven A.; Pu, Yunjiao
- Abstract
Evidence of positive polarity dominated streamers preceding fast negative breakdown (FNB) and of simultaneous positive and negative polarity streamer development in lightning initiation is reported. Observations of lightning initiation as FNB have remained a puzzle because simulations of lightning initiation have shown that negative streamers are not produced in virgin air without simultaneous positive streamers. Here, the authors observe positive streamer development forms first or at least simultaneously with negative streamers. Further evidence comes from observations of mixed fast breakdown (FB). The overall trajectory of the positive breakdown during such mixed events indicates that the positive streamers continuously propagate during the burst of strong negative breakdown. These observations indicate that even when negative streamers dominate the overall very high frequency (VHF) emissions, both positive and negative streamers are propagating simultaneously from the initiation point. These findings on the structure and dynamics of FB provide key new insight to our understanding of lightning initiation. Plain Language Summary: Lightning initiation remains a complex and poorly‐understood process. Recent observations have indicated that lightning initiation can sometimes occur through a burst of negative polarity streamers called FNB. However, our understanding of streamer initiation says that positive polarity streamers should always initiate first. We used high bandwidth and fast time resolution VHF interferometry to examine in greater detail of the development of FB during first several microseconds. We find strong evidence that FNB in fact begins with streamer systems containing positive streamers, and transitions to negative streamer dominance after 1–2 μs. Further evidence for unseen positive streamer development comes from observations of mixed FB, in which a strong burst of negative streamers masks the development of continuous positive streamers that become visible only after the negative streamer emissions get weakened. These observations show that even when negative streamers dominate the overall VHF emissions in FB, positive and negative streamers are both likely propagating simultaneously from the initiation point. These observations represent a significant addition to our current physical understanding of lightning initiation. Key Points: Fast breakdown of both polarities appears to begin with an around 1 μs burst of positive‐dominated streamer developmentNewly identified mixed fast breakdown exhibits simultaneous upward and downward streamer developmentWe conjecture that many fast breakdown events consist of simultaneous positive and negative streamer development
- Subjects
LIGHTNING; THUNDERSTORMS; POSITIVE systems; INTERFEROMETRY
- Publication
Geophysical Research Letters, 2021, Vol 48, Issue 8, p1
- ISSN
0094-8276
- Publication type
Article
- DOI
10.1029/2020GL091553