Geophysics

What Causes Sprites?

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Science  01 Apr 2005:
Vol. 308, Issue 5718, pp. 19
DOI: 10.1126/science.308.5718.19c

Sprites are transient luminous events in the mesosphere, at heights of about 50 to 90 km. They are associated with positive cloud-to-ground lightning, but may occur up to 50 km from the location of the lightning strike, with a delay of up to 100 ms. The mechanism by which sprites are generated and evolve is not well understood.

Ohkubo et al. have analyzed 21 sprites detected on 15 December 2003 during thunderstorms above the coast of the Sea of Japan. By comparing optical measurements with data taken at very low radio frequencies, the authors show that low-frequency discharges occur within the cloud at the same time as the sprite. These intracloud discharges may generate the sprites and help to explain the long time delay between cloud-to-ground lightning and sprite formation. — JFU

Geophys. Res. Lett. 32, 10.1029/2004GL021943 (2005).

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