Sprites are large scale electrical discharges that occur high above thunderstorm clouds, or cumulonimbus, giving rise to  varied range of visual shapes flickering in the night sky. They are triggered by the discharges of positive lightning between an underlying thundercloud and the ground. Sprites are colored reddish-orange in the upper regions, with bluish hanging tendrils below, and can be preceded by a reddish halo.  Sporadic visual reports of sprites go back at least to 1886, but they were first photographed on July 6, 1989 by scientists from the University of Minnesota and have subsequently been captured in video recordings many thousands of times.

Sprites have been observed over North America, Central America, South America, Europe, Southern Africa (Zaire), Australia, the Sea of Japan, and Asia and are believed to occur during most large thunderstorm systems. Sprites appear as luminous reddish-orange flashes, last longer than normal lower stratospheric discharges (typically a few milliseconds)(an unconfirmed observation of 4 sprites lasting over 1 hour in Zaire circa 1995), and are triggered by the discharges of positive lightning between the thundercloud and the ground. They often occur in clusters of two or more, and typically span the altitude range 50 kilometers (31 mi) to 90 kilometers (56 mi), with what appear to be tendrils hanging below, and branches reaching above.

Sprites are actually clusters of small, decameter-sized (10-100 m, 30-300 ft) balls of ionization that are launched at an altitude of about 80 km and then move downward at speeds of up to ten percent the speed of light, followed a few milliseconds later by a separate set of upward moving balls of ionization.

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