Sprite (lightning)

[3] Nobel laureate C. T. R. Wilson had suggested in 1925, on theoretical grounds, that electrical breakdown could occur in the upper atmosphere, and in 1956 he witnessed what possibly could have been a sprite.

They were first documented photographically on July 6, 1989, when scientists from the University of Minnesota, using a low-light video camera, accidentally captured the first image of what would subsequently become known as a sprite.

[4] Several years after their discovery they were named sprites (air spirits) after their namesake mythological entity based on their elusive nature.

A featured high speed video that was captured by Thomas Ashcraft, Jacob L Harley, Matthew G McHarg, and Hans Nielsen in 2019 at about 100,000 frames per second is fast enough to provide better detailing of how sprites develop.

[13] They often occur in clusters of two or more, and typically span the altitude range 50 to 90 kilometres (31 to 56 mi), with what appear to be tendrils hanging below, and branches reaching above.

In order to film sprites from Earth, special conditions must be present: 150–500 km (93–311 mi) of clear view to a powerful thunderstorm with positive lightning between cloud and ground, red-sensitive recording equipment, and a black unlit sky.

[15] Sprites occur near the top of the mesosphere at about 80 km altitude in response to the electric field generated by lightning flashes in underlying thunderstorms.

In the low pressure of the upper mesosphere the breakdown voltage is drastically reduced, allowing for an electron avalanche to occur.