NASA Image Reveals 'Red Sprites' Floating Above Thunderstorm

An astronaut aboard the International Space Station (ISS) has snapped a picture of a rare and spectacular atmospheric phenomenon.

NASA astronaut Matthew Dominick captured a form of lightning known as "red sprites" in the upper atmosphere on June 3.

These branching red flashes are a form of strange weather event known as Transient Luminous Events (TLEs), and are associated with intense thunderstorms.

Red sprites occur far above these thunderstorms, specifically in the mesosphere, and are a form of lightning that rather than going toward the ground, shoot up into the atmosphere.

Sprites are triggered by positive cloud-to-ground lightning strikes, which transfer a large amount of charge to the ground, leaving the thundercloud with a strong negative charge. The electric field produced by these lightning strikes can then exceed the breakdown threshold of the upper atmosphere due to the lower pressure, creating these bizarre sprites as a kind of secondary lightning. Some sprites may be up to 30 miles across.

"Red sprites are one type of visible manifestation of electrical discharges that occur at altitudes of 35-50 miles, far above the top of active thunderstorms or other strongly electrified clouds which produce lightning strokes," József Bór, a lightning researcher at the Institute of Earth Physics and Space Science (ELKH EPSS) in Hungary, told Newsweek.

"Red sprites are practically high altitude lightning which looks like this because in that altitude range, atmospheric pressure is about 10,000 times smaller than that at sea level. So the air is generally very thin but not only that. These events may span a height range of 10-30 miles over which the pressure exhibits more than 10-fold change (grows downward)."

Sprites often have a red or reddish-orange color at higher altitudes, with bluish tendrils extending downward. This red color comes from the excitation of nitrogen molecules by the electrical discharge. They typically appear as clusters of vertical columns, resembling jellyfish or carrot shapes, and last for less than a tenth of a second.

"Red sprites do not appear very frequently because very strong lightning strokes capable of producing them don't occur very often. The appearance of red sprites indicates that extremely strong lightning has occurred in the underlying thunderstorm," Bór said.

Other types of TLE include blue jets, elves, halos, ghosts, trolls, gigantic jets, gnomes, and pixies, all of which are other short-lived optical phenomena occurring above thunderstorms in the upper atmosphere.

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