Blue jets and elves lightning
Thunderstorms monitored by the Danish-led ASIM mission delivers historical data for groundbreaking science discovery now revealed in the prestigious Nature magazine.
Blue jets are a form of lightning that travels from the top of thunder clouds into space. Lasting fractions of a second, and their origin is still under debate. The blue jet, detected by ASIM, was observed over a thunderstorm close to the island of Nauru in the Pacific Ocean. Five blue flashes in the cloud top layer were observed, with one generating the blue jet.
Blue jets are electric discharges of several hundred millisecond duration that fan into cones as they propagate from the top of thunderclouds into the stratosphere. They are thought to initiate in an electric breakdown between the positively charged upper region of a cloud and a layer of negative charge at the cloud boundary and in the air above.
Here we report spectral measurements from the International Space Station, which offers an unimpeded view of thunderclouds, with 10-microsecond temporal resolution. We observe five intense, approximately 10-microsecond blue flashes from a thunderstorm cell. One flash initiates a pulsating blue jet to the stratopause (the interface between the stratosphere and the ionosphere).
The observed flashes were accompanied by ‘elves’ in the ionosphere. We propose that the microsecond flashes are the optical equivalent of negative narrow bipolar events observed in radio waves. These are known to initiate lightning within the cloud and to the ground, and blue lightning into the stratosphere, as reported here.
https://www.nature.com/articles/s41586-020-03122-6
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