by APOD Robot » Mon Feb 08, 2010 4:54 am
A Sun Halo Over Cambodia
Explanation: Have you ever seen a halo around the Sun? This fairly common sight occurs when
high thin clouds containing millions of tiny
ice crystals cover much of the sky. Each
ice crystal acts like a
miniature lens. Because
most of the crystals have a similar elongated
hexagonal shape, light entering one crystal face and exiting through the opposing face refracts 22
degrees, which corresponds to the radius of the
Sun halo. A similar
Moon halo may be visible during the night.
Pictured above, a nearly complete
sun halo was photographed high above the ancient
Bayon temple in
Angkor,
Cambodia. Exactly how
ice-crystals form in clouds remains under
investigation.
[/b]
[url=http://apod.nasa.gov/apod/ap100208.html][img]http://apod.nasa.gov/apod/calendar/S_100208.jpg[/img] [size=150]A Sun Halo Over Cambodia[/size][/url]
[b] Explanation: [/b] Have you ever seen a halo around the Sun? This fairly common sight occurs when [url=http://ww2010.atmos.uiuc.edu/%28Gh%29/guides/mtr/cld/cldtyp/hgh/crs.rxml]high thin clouds[/url] containing millions of tiny [url=http://www.its.caltech.edu/~atomic/snowcrystals/photos/photos.htm]ice crystals[/url] cover much of the sky. Each [url=http://en.wikipedia.org/wiki/Ice_crystal]ice crystal[/url] acts like a [url=http://en.wikipedia.org/wiki/Halo_%28optical_phenomenon%29]miniature lens[/url]. Because [url=http://www.atoptics.co.uk/halo/xtalreal.htm]most[/url] of the crystals have a similar elongated [url=http://apod.nasa.gov/apod/ap091214.html]hexagonal[/url] shape, light entering one crystal face and exiting through the opposing face refracts 22 [url=http://mintaka.sdsu.edu/GF/explain/atmos_refr/angles.html]degrees[/url], which corresponds to the radius of the [url=http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/opt/ice/halo/22.rxml]Sun halo[/url]. A similar [url=http://apod.nasa.gov/apod/ap030321.html]Moon halo[/url] may be visible during the night. [url=http://indafoto.hu/naked/image/6713745-796bca69/details/m]Pictured above[/url], a nearly complete [url=http://apod.nasa.gov/apod/ap060613.html]sun halo[/url] was photographed high above the ancient [url=http://en.wikipedia.org/wiki/Bayon_Temple]Bayon temple[/url] in [url=http://en.wikipedia.org/wiki/Angkor]Angkor[/url], [url=http://en.wikipedia.org/wiki/Cambodia]Cambodia[/url]. Exactly how [url=http://www.its.caltech.edu/~atomic/snowcrystals/primer/primer.htm]ice-crystals form[/url] in clouds remains under [url=http://adsabs.harvard.edu/abs/1995dri..rept.....H]investigation[/url].
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