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Thread: Rainbow before the storm

  1. #1
    Join Date
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    Rainbow before the storm

    My Lovely Bride took this iPhone photo from the deck a bit ago as a storm was approaching. The horses didn't seem to notice the rainbow or the storm.

    rainbow_sharon_IMG_1535.jpg

    JKJ

  2. #2
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    Nice picture! Interesting contrast above and below the rainbow.
    Above looks very ominous.

    Tim

  3. #3
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    West Lafayette, IN
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    Gotta do it: Double Rainbow!!!

  4. #4
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    Alexander's Dark Band

    Quote Originally Posted by Tim Janssen View Post
    Nice picture! Interesting contrast above and below the rainbow.
    Above looks very ominous.
    Tim,

    The dark area above the primary rainbow turns out to be an optical effect. It was evidently first described by Alexander of Aphrodisias in 200 AD (a while back!) so it is called Alexander's Band or Alexander's Dark Band. Note that the area between the two rainbows in this picture is darker than the sky above and below. (I took this picture about 10 years ago from the same spot.)

    rainbow_alexanders_dark_ban.jpg

    I developed my own theory of why this is. When at the Oak Ridge National Laboratory I ran into one of the world's experts on rainbows. I showed him this picture where you can easily see tiny rainbows inside the primary rainbow:

    rainbow_supernumerary_arcs_.jpg

    He said rainbow scientists call these "supernumerary arcs" or "supernumerary bows." It looks to me like there might be many of these arcs, getting smaller and less distinct the further they are inside the rainbow. My theory about the dark band was these arcs lighten the area inside the primary rainbow (and to a lesser extent, outside the secondary rainbow) causing the band between them to look darker, in effect, an optical illusion. You can see this in the first picture in this message.

    Our horse pasture faces east and has turned out to be an excellent spot to see rainbows. Since the weather usually comes from the west, a shower that passes us late in the afternoon might move to the east just as the sun comes out again low in the west making a perfect rainbow. The one today was unusual since the storm came from the east but the light was about the same. The rain was already falling at the end of the field so the rainbow actually extends down over the field. I walked out there but didn't see a pot of gold...

    JKJ

  5. #5
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    Great photo. It helps to get your head around the effect when you realise it is 3 dimensional. Any of you guys get moon bows? We get them when it is clear at the house and snow showers on the Western Tiers as full moon. Photos don't show what the eye sees however. To the eye they are pure white but the camera shows the colours. Cheers

  6. #6
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    Here's a double rainbow photo I took near Craters of the Moon National Monument in August 2014. Although the photo doesn't show it the double rainbow was visible all the way across the sky to the ground on the other side.
    IMG_8473-sm.jpg
    Lee Schierer
    USNA '71
    Go Navy!

    My advice, comments and suggestions are free, but it costs money to run the site. If you found something of value here please give a little something back by becoming a contributor! Please Contribute

  7. #7
    Beautiful ,but now we know about your shipping container full of gold !!

  8. #8
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    Quote Originally Posted by Mel Fulks View Post
    Beautiful ,but now we know about your shipping container full of gold !!
    A friend pointed out that the rainbow in my field yesterday points directly at my beehives just behind the trees to the left of the white horse trailer. Liquid gold.

    BTW, the rainbow yesterday did extend further. She used the phone panoramic algorithm to grab this, a little sloppy for a photograph but very quick:

    rainbow_sharon_pano.jpg

    [sigh] This farm is a terrible place to live but somebody has to do it... :-)

    JKJ

  9. #9
    Love these pics!

    this was at our boat harbor in Oct. 2011, from our boat parked at the shore--

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  10. #10
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    Quote Originally Posted by Kev Williams View Post
    Love these pics!
    this was at our boat harbor in Oct. 2011, from our boat parked at the shore--
    Wow! Looks like the sun was nearly on the horizon. With the trees and hills here we will never see that much of the arc!

    This is one of the most complete web sites that concern rainbows and other atmospheric optical things. It's one to bookmark!

    http://www.atoptics.co.uk/bows.htm

    JKJ

  11. #11
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    Quote Originally Posted by Mel Fulks View Post
    Beautiful ,but now we know about your shipping container full of gold !!
    Yeah, too bad it isn't my shipping container. And since there are several thousand of containers just like that one and they are always being moved around you would still need to catch a leprechaun to find the gold.
    Lee Schierer
    USNA '71
    Go Navy!

    My advice, comments and suggestions are free, but it costs money to run the site. If you found something of value here please give a little something back by becoming a contributor! Please Contribute

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