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    A halo-like rainbow round the Sun: some sextant measurements.
    From: Tony Oz
    Date: 2017 May 17, 05:04 -0700

    Hello!

    Few days ago the clouds (like these, the cirrus uncinus and cirrus fibratus) were obscuring the Sun in the evening. One part of the cloud layer was colored like a raindow sector. The red band was at ~20°10' from the Sun, the violet band was at ~20°30'. I.e., unlike the usual (seen away from the Sun) raindow which has violet band closer to the center of its' arc - this one was "reversed". It was around the Sun and color order was reversed too.

    I could not find the data about the angular width of the usual rainbow, but I vaguely recall it is wider than those 20° radius I measured for that halo. Next time I see a regular rainbow - I hope I'll have the sextant with me.

    Regards,

    Tony

       
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