Double rainbows: Here's what they mean

The physics blog Skulls in the Stars has answers to your rainbow-related questions. Among the fascinating things we learn here — each color in a rainbow represents the light reflected by a separate group of raindrops; skydivers can see circular rainbows; and the famous double rainbow happens when light bounces off the inside of a raindrop not just once ... but twice.


  1.  Easiest way to locate a faint rainbow is to turn your back to the sun and stretch your arms straight out in front of you and spread your hands like you are trying to make a shadow puppet bird — the rainbow should be grazing the tips of your fingers on both hands…  (makes the 42 degree angle)

  2. Twice in my life I’ve seen full double rainbows. Once in an airplane I saw a full circle rainbow. And a few years ago, driving on the highway at sunset, one end of the rainbow set on the highway ahead, so the oncoming cars were colored by it. (This settled my question as to whether rainbows could be somewhere in particular, or just…in a direction. Well, they’re both, I suppose.)

    I’d love to see a fogbow, but I live in the Mojave desert, and I’m not holding my breath.

      1. “God gave Noah the rainbow sign, no more water but fire next time” ((and given global climate change…))

  3. An interesting consequence of the physics of rainbows is that each instance of seeing rainbow is a unique relationship between a light source, water droplets, and an observer. No two people have ever seen the same rainbow.

    I’ve seen a fogbow from the Hartman bridge in Baytown, TX. Seems like that would also be a good place to see a Brocken Spectre too, but I think the DHS would hassle me if I spent every foggy winter morning looking for one.

    1.  “Excuse me citizen, what are you doing?”
      “Looking for beautiful things. Sometimes the light is really amazing here”
      */taser sound, dragged into waiting van/*


  4. My only experience with anything like a double rainbow was sometime around 2001. This was in the small town of Lismore in northern NSW, Australia. While walking home I stopped to chat to a friend who was passing by. I don’t know who saw the rainbow first. But it was full and particularly bright. Before long we noticed a second rainbow. And then a third.

    After some time the spaces in between the three rainbows began to fill with the colours of more rainbows until there was no break between any of them. The effect it gave was of a giant open air dome. What would cause such an illusion?

  5. One of my favorite factoids: at the center of every rainbow is your own shadow! (Not the “middle,” the center.) Usually only visible from an airplane…or while skydiving apparently.

  6. err, surely it would have to be reflected *thrice*, as I seem to recall from my physics classes. twice would have the light pointing in a direction similar to its original one, away from the sun again.

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