Eric Berger, writing for Ars Technica:
Scientists don’t know much about the mysterious, powerful electric discharges that sometimes occur in the upper levels of the atmosphere in conjunction with thunderstorms. The first photograph of the phenomenon—which can occur as high as about 90km above the surface of the Earth and are known variously as sprites, pixies, elves, or jets—was only taken from Earth in 1989.
Fortunately for scientists interested in these storms, the International Space Station offers an excellent vantage point at an altitude of about 400km. So Danish researchers devised a “Thor experiment”—named after the hammer-wielding Norse god—to study the phenomenon. As part of the experiment, an astronaut on board the station would image thunderstorms under certain conditions, and these observations would be correlated with data collected by satellites and ground-based radar and lightning detection systems.
It has been interesting seeing more and more proper research going into these upward-directed electric discharges from thunderstorms. I recall just in the early 2000’s stories about pilots who had seen these phenomenon but didn’t share their experiences because they felt people may not believe them.
Now we know not only that these blue flashes exist, among other upper-atmosphere related phenomenon, but also that thunderstorms may have a role in troposphere-stratosphere gas exchange.
- Chanrion, O., T. Neubert, A. Mogensen, Y. Yair, M. Stendel, R. Singh, and D. Siingh (2017), Profuse activity of blue electrical discharges at the tops of thunderstorms, Geophys. Res. Lett., 44, 496–503, doi:10.1002/2016GL071311. ↩