Multi-Pulse Corona Discharges in Thunderclouds Observed in Optical and Radio Bands

How lightning initiates inside thunderclouds remains a major puzzle of atmospheric electricity. By monitoring optical emissions from thunderstorms, the Atmosphere-Space Interactions Monitor (ASIM) onboard the International Space Station is providing new clues about lightning initiation by detecting Blue LUminous Events (BLUEs), which are manifestations of electrical corona discharges that sometimes precedes lightning. Here we combine optical and radio observations from a thunderstorm near Malaysia to uncover a new type of event containing multiple optical and radio pulses. We find that the first optical pulse coincides with a strong radio signal in the form of a Narrow Bipolar Event (NBE) but subsequent optical pulses, delayed some milliseconds, have weaker radio signals, possibly because they emanate from a horizontally oriented electrical discharges which does not trigger full-fledged lightning. Our results cast light on the differences between isolated and lightning-initiating electrical discharges.

Automated summary

This study investigates lightning initiation inside thunderclouds by monitoring optical emissions and radio observations. The researchers uncover a new type of event that contains multiple optical and radio pulses. The first optical pulse coincides with a strong radio signal, while subsequent optical pulses, delayed by milliseconds, have weaker radio signals, indicating a difference between isolated electrical discharges and lightning-initiating discharges.