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Thread: Circumzenithal Arc

  1. #1
    tybrad's Avatar
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    Circumzenithal Arc

    I am fascinated with atmospheric phenomena. As is usual, they are best pinned to something Earthly, so I framed with a gnarled pine nearby.

    Here is one- a circumzenithal arc. They are a bit unusual since they arc AWAY from the solar point and arise from refraction of sunlight through horizontally-oriented ice crystals, generally in cirrus clouds, rather than from raindrops. It forms no more than one-quarter of a circle centered on the zenith and on the same side as the sun. Its colors are from blue on the inside to red on the outside of the arc. It is one of the brightest and most colorful solar halos. Its colors are purer than those of the rainbow because there is much less color overlap in its formation. The first impression is that of an upside-down rainbow.

    C&C welcomed.

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    Circumzenithal Arc

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    Circumzenithal Arc

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    Circumzenithal Arc
    Last edited by tybrad; 15th November 2012 at 10:37 PM.

  2. #2
    Moderator Dave Humphries's Avatar
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    Re: Circumzenithal Arc

    A very educational series Tyler

    Well done,

  3. #3

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    Re: Circumzenithal Arc

    The second image certainly brings everything together as a good scenic shot.

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    MilT0s's Avatar
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    Re: Circumzenithal Arc

    Ah, new knowledge combined with nice photos!

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    Re: Circumzenithal Arc

    Hi Tyler,

    Thanks for the image and information. I never knew that was what it was called, I thought it was still called a rainbow.
    Interesting though is that when I looked at the one I photographed a couple of weeks ago in the Kosciuszko National Park it was upside down compared to yours. Now I know that we are in the southern hemisphere but that surprises me as I thought we are looking at a refraction pattern of light which doesn't have an up or down. I will have to do a bit of re-thinking....

    Circumzenithal Arc

    I only took casually because it was there when I was doing something else thinking it would be good for a collection of sky for blending into other images later. I didn't really know how best to process it but this was how I saw it. I had a 70 - 200 lens on at the time and I could only get this much.

    Graham

  6. #6

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    Re: Circumzenithal Arc

    I like the first image best and especially appreciate the explanation.

    A polarizer will enhance or completely eliminate a rainbow, depending on the position of the filter. Am I right that the same thing would happen when using a polarizer to capture a circumzenithal arc?

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