For centuries, pilots and ship captains had occasionally reported strange flashes of red light high above thunderstorms - but most scientists dismissed the sightings. Then in 1989, a research team at the University of Minnesota accidentally captured one on video while testing equipment. The flash was real, lasted only a few milliseconds, and was a vivid red. It was named a sprite, and a whole new category of lightning had been discovered.
Sprites occur between 50 and 90 kilometers above the ground - way above normal lightning, which happens within thunderstorm clouds at a few kilometers’ altitude. They form when an extremely powerful positive lightning bolt strikes the ground from a thunderstorm, creating a sudden electrical imbalance high in the atmosphere. The result is a ghostly column of red plasma, shaped like a jellyfish or carrots, flashing for less than a tenth of a second.
Since the discovery of sprites, scientists have identified other related upper-atmosphere lightning phenomena: blue jets, elves, halos, gigantic jets. They’re now collectively called transient luminous events, and there’s a whole upper-atmosphere weather system that we hadn’t even known existed until recently. The International Space Station has captured spectacular footage of sprites flashing above storms on Earth.
