Airplane pilots have spotted "transient luminous events" since the dawn of aviation, "but many were afraid to report the [flashes of light] because of their elusive nature," commented Victor P. Pasko at Penn State University's Communications and Space Sciences Laboratory in University Park.
However, the first image was captured in 1989, quite accidentally during the testing of a low-light-level television camera. Since then, said Pasko, who has penned a commentary on the new discovery also published in Nature, several different types of transient luminous events have been discovered and filmed on many occasions.
Sprites are red in color and spread out in bright tendrils of light. They appear above active thunderstorms and accompany strong lightning strikes. These flashes can stretch 50 kilometers (about 30 miles) across and reach up into the ionosphere, but don't reach down as far as cloud level. Blue jets on the other hand, shoot out from the core regions of thunderstorms, but usually do not reach higher than 40 to 50 kilometers (25 to 30 miles) in height. Other types of luminous event, called elves, crawlers, trolls, and pixies, have also been recorded.
"Gigantic jets are a really new and exciting finding," said Pasko, and appear to be an electric link between the thunderclouds and the ionosphere. "Globally these jets could also be playing an important role in atmospheric chemistry," said Pasko. In a similar way to lightning, the discharges of current from these jets could cause reactions between gases to produce ozone and could be playing an important role in our planet's chemical cycles, said Pasko.
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