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Дата изменения: Tue Nov 8 13:23:59 2011
Дата индексирования: Sun Feb 3 11:25:22 2013
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Поисковые слова: trifid nebula
Jumping Sundogs Over Thunderclouds
Astronomy Picture of the Day
    


Jumping Sundogs Over Thunderclouds
<< Yesterday 8.11.2011 Tomorrow >>
Credit & Copyright: abrigatti, YouTube
Explanation: What's happening above those clouds? In the past few years, videos have appeared on the web detailing an unusual but little known phenomenon: rapid light changes over clouds. Upon inspection and contemplation, a leading hypothesis for its cause has now emerged. In sum, this hypothesis holds that a lightning discharge in a thundercloud can temporarily change the electric field above the cloud where charged ice crystals were reflecting sunlight. The new electric field quickly re-orients the geometric crystals to a new orientation that reflects sunlight differently. In other words, a lightning discharge can cause a sundog to jump. Soon, the old electric field may be restored, causing the ice crystals to return to their original orientation. To help this curious phenomenon become better studied, sky enthusiasts with similar jumping or dancing sundog videos are encouraged to share them.

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.

Based on Astronomy Picture Of the Day

Publications with keywords: Sun dogs - lightning - thunderstorm - clouds
Publications with words: Sun dogs - lightning - thunderstorm - clouds
See also:
All publications on this topic >>