22° halos form when the sky contains millions of poorly oriented ice crystals. Some of these happen to be aligned perpendicular to the sun light as viewed by one observer which produces the illuminated 22° circle, while other crystals produces the same phenomenon for other observers.
Like other ice halos, 22° halos appear when the sky is covered by thin cirrus clouds containing the ice crystals which causes the phenomenon. Small colourful coronas much nearer the sun produced by water droplets can occasionally be confused with 22° halos. -Wikipedia
Thursday, December 27, 2007
Golden Sundog
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I just learned about circumhorizon arcs, and thought you would enjoy this link http://www.atoptics.co.uk/halo/common.htm
which doesn't show the circumhorizon arc but does show the different halo effects.
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