[AZ-Observing] Re: [Fwd: CHECK THIS RAINBOW!]
- From: "Bernie Sanden" <bsanden@xxxxxxx>
- To: <az-observing@xxxxxxxxxxxxx>
- Date: Mon, 12 Mar 2007 21:12:16 -0700
On June 24th 2006 at the Grand Canyon star party, I took this shot of a
circumhorizontal arc. It's not as dramatic as the Idaho shot but that
may be because I didn't pump up the saturation since I wanted to retain
the visual impression. This shot was taken near Yavapai overlook at the
rim in the early afternoon:
http://www.pbase.com/bsanden/image/63187567
I know Brad Nevers from the Las Vegas club captured the same display,
but his www.starnevada.com site appears to be down.
- Bernie
-----Original Message-----
From: az-observing-bounce@xxxxxxxxxxxxx
[mailto:az-observing-bounce@xxxxxxxxxxxxx] On Behalf Of Brian Skiff
Sent: Monday, March 12, 2007 2:16 PM
To: az-observing@xxxxxxxxxxxxx
Subject: [AZ-Observing] Re: [Fwd: CHECK THIS RAINBOW!]
Thanks for the link. I assumed it was a recent photo,
necessitating the circumzenithal arc (low Sun), whereas the caption
says it was taken in June 2006, which is the season when you'd
expect the circumhorizontal arc (high Sun, arc fairly low in the sky).
The photo does show the irridescent character of the light very well.
Yes, they are uncommon, but I wouldn't call them "rarest"
by a long shot. We get them pretty regularly in Arizona particularly
in late spring when there is still some cirrus around of the right
sort but with the Sun above 58 deg elevation. (It doesn't have to
be exactly that angle, just _above_ that elevation.) As I recall,
the crystals in the clouds have to be dominated by ones hanging nearly
vertical (imagine a six-sided pencil with a umbrella-like snowflake
cap on end end---the whole thing about 1mm long or less).
More details (and photos) can be found at Les Cowley's excellent
atmospheric optics pages:
http://www.atoptics.co.uk/halo/cha.htm
\Brian
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