First confirmation of upper-atmosphere 'sprites'

Settled in 1990 by R.C. Franz, R.J. Nemzek, J.R. Winckler (University of Minnesota).

Airline pilots had reported brief upward flashes above thunderstorms for decades, but without instrumental evidence the phenomenon was widely dismissed by atmospheric scientists as anecdotal. In 1989, a low-light television camera being tested by Franz, Nemzek and Winckler at the University of Minnesota accidentally captured an unambiguous image of a large discharge extending from a storm's cloud tops up roughly 20 km into the clear air above, published in Science in 1990. This first instrumental confirmation launched the now-large field of 'transient luminous events' (sprites, jets, elves), later studied extensively via space shuttle video and dedicated campaigns. It remains a textbook case of folklore preceding, and eventually being vindicated by, rigorous instrumental science.

A phenomenon pilots had quietly reported to each other for generations turned out to be a real, enormous electrical discharge reaching from thunderclouds into the edge of space, caught almost by accident on a low-light camera.

Explanations that circulated

• Early anecdotal pilot reports were commonly dismissed by scientists as optical illusions, camera artifacts, or confusion with St. Elmo's fire rather than genuine large-scale electrical discharges reaching the mesosphere

References

• Television Image of a Large Upward Electrical Discharge Above a Thunderstorm System, R. C. Franz, R. J. Nemzek, J. R. Winckler, Science, 1990