by APOD Robot » Tue Feb 21, 2012 5:07 am
Anticrepuscular Rays Over Wyoming
Explanation: What's happening over the horizon? Although the scene may appear somehow
supernatural, nothing more unusual is occurring than a
setting Sun and some well placed clouds. Pictured above are
anticrepuscular rays. To understand them, start by picturing common
crepuscular rays that are seen any time that
sunlight pours though scattered clouds. Now although sunlight indeed travels along
straight lines, the projections of these lines onto the
spherical sky are
great circles. Therefore, the
crepuscular rays from a
setting (or rising) sun will appear to
re-converge on the other side of the sky. At the anti-solar point 180 degrees around from the
Sun, they are referred to as
anticrepuscular rays. Pictured above is a particularly striking set of
anticrepuscular rays photographed last month near
Cheyenne,
Wyoming,
USA.
[/b]
[url=http://apod.nasa.gov/apod/ap120221.html][img]http://apod.nasa.gov/apod/calendar/S_120221.jpg[/img] [size=150]Anticrepuscular Rays Over Wyoming[/size][/url]
[b] Explanation: [/b] What's happening over the horizon? Although the scene may appear somehow [url=http://en.wikipedia.org/wiki/The_Demon-Haunted_World]supernatural[/url], nothing more unusual is occurring than a [url=http://apod.nasa.gov/apod/ap980526.html]setting Sun[/url] and some well placed clouds. Pictured above are [url=http://www.atoptics.co.uk/atoptics/anti1.htm]anticrepuscular rays[/url]. To understand them, start by picturing common [url=http://en.wikipedia.org/wiki/Crepuscular_rays]crepuscular rays[/url] that are seen any time that [url=http://apod.nasa.gov/apod/ap050831.html]sunlight pours[/url] though scattered clouds. Now although sunlight indeed travels along [url=http://www.theory.caltech.edu/people/patricia/grelb.html]straight lines[/url], the projections of these lines onto the [url=http://math.rice.edu/~pcmi/sphere/]spherical sky[/url] are [url=http://en.wikipedia.org/wiki/Great_circle]great circles[/url]. Therefore, the [url=http://www.allthesky.com/atmosphere/sunrays.html]crepuscular rays[/url] from a [url=http://apod.nasa.gov/apod/ap010313.html]setting (or rising) sun[/url] will appear to [url=http://www.youtube.com/watch?v=H9C-fodX95c]re-converge[/url] on the other side of the sky. At the anti-solar point 180 degrees around from the [url=http://apod.nasa.gov/apod/sun.html]Sun[/url], they are referred to as [url=http://en.wikipedia.org/wiki/Anticrepuscular_ray]anticrepuscular rays[/url]. Pictured above is a particularly striking set of [url=http://www.youtube.com/watch?v=0nCY-sBhwqM]anticrepuscular rays[/url] photographed last month near [url=http://en.wikipedia.org/wiki/Cheyenne,_Wyoming]Cheyenne[/url], [url=http://en.wikipedia.org/wiki/Wyoming]Wyoming[/url], [url=https://www.cia.gov/library/publications/the-world-factbook/geos/us.html]USA[/url].
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