Speaker
Description
The initiation mechanism of lightning flash remains poorly understood in
modern atmospheric physics, despite decades of observational and theoretical efforts. Gurevich et al. proposed that abundant low-energy electrons produced during
relativistic runaway electron avalanche process (RREA) can utilize hydrometeors as "amplifiers" to form a high-conductivity region, thereby reaching the conditions for
lightning initiation. This highlights the necessity of investigating the relationship
between lightning flash and hydrometeors. In this work, the correlation between
lightning activity and relative humidity (RH) during January 2022–August 2026 is
statistically analyzed using atmospheric electric field and meteorological data from
the LHAASO site (~4410 m a.s.l., Daocheng, Sichuan, China). The results show that
approximately 96% of lightning events are accompanied by an increase in relative
humidity. Meanwhile, lightning activity is frequent when RH ranges between 60%
and 90%, while it is markedly suppressed above 90%, accompanied by a sharp
decrease in flash counts. Lightning event are sparse when RH is below 60%, and no
lightning occurs when RH is below 35%. These results suggest that hydrometeors
may play a key role in lightning initiation, and this study provides observational
information for understanding the lightning initiation mechanism and its correlation
with humidity at high altitudes.
