22º halo image index
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Lunar halo and aurora. Imaged in Norway by Arne Danielsen (astrophotography
and atmospheric phenomena) during the great auroral display
over Europe on 21st January 2005. The ice crystals of the thin cirrus
layer that created the halo are well below the glowing atoms of the
aurora. The Pleiades and Taurus are to the right of the moon, Castor
and Pollux to the left and Saturn lower left. |
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The moon was high in the sky when this image was taken. Whenever the
sun or moon is high and a circular halo is seen, it could be a circumscribed
halo produced by horizontal columns rather than a 22º
halo made by poorly oriented crystals. The two are not easy to distinguish
but the circumscribed halo is slightly sharper with brighter colours
-- it is usually also accompanied by a parhelic circle. This one looks
like a 22º halo. |
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