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Crown flash

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Crown Flash - a rare but observed phenomenon involving "The brightening of a thunderhead crown followed by the appearance of aurora-like streamers emanating into the clear atmosphere" [1]. The current hypothesis is that sunlight is reflecting off or refracting through tiny ice crystals above the crown of a cumulonimbus cloud. These ice crystals are aligned by the strong electro-magnetic effects around the cloud [2], so the effect may appear as a tall streamer or pillar of light. When the electro-magnetic field is disturbed by lightning flashes within the cloud, the ice crystals are re-orientated causing the light pattern to shift very rapidly and appear to 'dance' in a strikingly mechanical fashion. The effect may also sometimes known as a "leaping sundog" [3]. As with sundogs, the observer would have to be in a specific position to see the effect, which is not a self-generated light such as seen in a lightning strike, but rather a changing reflection of the sunlight.

Mentioned in Nature [4] and in a letter to Nature slightly earlier in the same year[5], this phenomenon was regarded as rare and not well documented. Recently several Youtube videos have emerged that appear to document this phenomenon - and some discussion around them.

  1. "Crown Flash" and Leaping Sundogs, Meteorological Phenomenon: parhelia altered by thunderstorm e-fields - 2009 Page by William Beatty - http://amasci.com/amateur/sundog.html
  2. "Leaping Streams of Light: A new natural phenonmenon?" - 2011 - http://forgetomori.com/2011/science/leaping-streams-of-light-a-new-natural-phenomenon/
  3. "A new Natural phenomenon Crown Flash" - 2011 - Follow up article - http://forgetomori.com/2011/science/a-new-natural-phenomenon-crown-flash/
  4. Discover Magazine - 2011 - http://blogs.discovermagazine.com/badastronomy/2011/10/25/amazing-video-of-a-bizarre-twisting-dancing-cloud/
  5. Youtube Playlist of Leaping Sundog / Crown Flashes - https://www.youtube.com/playlist?list=PLS8LbL7GIZiDcEf_E4GWRwKbx3fIFpW0p


References

  1. ^ Corliss, William (1982). Lightning, Auroras, Nocturnal Lights, and Related Luminous Phenomena: A Catalog of Geophysical Anomalies. ISBN 978-0915554096.
  2. ^ Vonnegut, B (1965). "Orientation of Ice Crystals in the electric field of a Thunderstorm". Weather. 20 (10): 310–312.
  3. ^ "A New Natural Phenomenon - Crown Flash". Retrieved 2015-09-03.
  4. ^ Graves, Maurice E.; Gall, John C.; Vonnegut, Bernard (1971). "Meteorological Phenomenon called Crown Flash". Nature. 231 (5300): 258.
  5. ^ Graves, Maurice E; Gall, John C (1971). "Possible Newly Recognized Meteorological Phenomenon called Crown Flash". Nature. 229: 184-185.
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