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| Image credit: Frankie Lucena. |
On September 18, Frankie Lucena of Cabo Rojo, Puerto Rico, photographed an enormous sprite over the Caribbean Sea. For a split-second, the sky was illuminated by a mushroom-shaped flash: Oscar van der Velde, a member of the Lightning Research Group at the Universitat Politecnica de Catalunya, explains what Lucena photographed:
''This type of sprite is often called 'jellyfish' or 'A-bomb,' and ranks as the largest type of sprite in both horizontal and vertical dimensions, '' he says. ''It consists of a bright halo approximately 85 km above Earth's surface surrounding sprite elements with long tendrils reaching down as low as 30 km above ground level.''
''This kind of sprite tends to be triggered by a very impulsive positive cloud-to-ground flash,'' van der Velde said to spaceweather.
The curios thing is, Lucena did not observe an instigating lightning bolt. Instead, just before the sprite appeared, he recorded a bright point-like flash of light. ''Was it a cosmic ray hitting the camera?'' wonders Lucena. Another possibility: The point-like flash could have been a cloud-to-ground strike mostly eclipsed by intervening clouds.
Source: spaceweather.com
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