# How did this weird rainbow formation happen? (pics) **URL:** \ **Category:** Factual Questions\ **Created:** [December 10, 2003, 12:11am UTC](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041 "2003-12-10T00:11:24Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [December 10, 2003, 12:11am UTC](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041/1 "2003-12-10T00:11:24Z")
So, with my new computer I am finally getting round to sorting out some of the (literally) thousands of digital photos I took on a trip round the world. I just got to a batch of pictures from the Cook Islands, which reminded me of something I found strange at the time… strange enough to take some photos. It was sunny, I was just returning from a boat trip on the lagoon, and there was a storm approaching. Cue rainbows as the rain arrived. But here’s the weird thing - whenever I’ve seen double rainbows before, they have been sections of concentric circles. But this weird formation – [pic 1](http://www.geocities.com/robkingston/rainbows.jpg) and [pic 2](http://www.geocities.com/robkingston/rainbows2.jpg) – caught my eye. I have boosted the contrast and saturation of these pictures just so you can see them easier - hence the addition of some random colour noise in the sky, but you can clearly see that there is an almost vertical rainbow coming off the main arc at a tangent. Can any meteorological or physics-minded folks explain this? My best guess is that a reflection of the sun in the water is also forming a rainbow, but I can’t really see why it would make that shape… ---
**Author:** ![Viscera](https://avatars.discourse-cdn.com/v4/letter/v/258eb7/32.png) [@Viscera](https://boards.straightdope.com/u/Viscera)\ **Post date:** [December 10, 2003, 12:17am UTC](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041/2 "2003-12-10T00:17:51Z")
Well, I think it has to be another source, since a double rainbow has it’s color lineup opposite of the primary rainbow. Your images have the orientation of each rainbow the same. Vis ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [December 10, 2003, 12:32am UTC](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041/3 "2003-12-10T00:32:13Z")
Hmm, good point… I hadn’t actually noticed that. There certainly weren’t any artificial light sources around… these pics were taken on the lagoon of [Aitutaki](http://www.jetsave.co.ck/aitutaki_island.htm), which is hardly a major conurbation 🙂 ---
**Author:** ![bughunter](https://avatars.discourse-cdn.com/v4/letter/b/aeb1de/32.png) [@bughunter](https://boards.straightdope.com/u/bughunter)\ **Post date:** [December 10, 2003, 12:32am UTC](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041/4 "2003-12-10T00:32:36Z")
Send your photos to the folks at [Earth Science Picture of the Day](http://epod.usra.edu/) and they may know more. Plus, they may put one of your pics up on their site and you can have your 15 minutes of internet fame! ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [December 10, 2003, 12:34am UTC](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041/5 "2003-12-10T00:34:27Z")
In the second of the pictures, the tree and water below the more vertical of the two features appear blurred - any idea what that is all about? ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [December 10, 2003, 12:36am UTC](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041/6 "2003-12-10T00:36:55Z")
**Mangetout** , I think that is just a drop of water on the camera lens - it had started to rain quite hard by that time. But the double rainbow effect was clear to the naked eye - it had nothing to do with that… in fact it is the only reason I had my camera out in the rain! ---
**Author:** ![Zazie](https://avatars.discourse-cdn.com/v4/letter/z/6f9a4e/32.png) [@Zazie](https://boards.straightdope.com/u/Zazie)\ **Post date:** [December 10, 2003, 12:40am UTC](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041/7 "2003-12-10T00:40:59Z")
I just saw a double rainbow in Prince Edward Island, Canada when visiting 3 weeks ago. I had never seen “one” before… well… two… Although they were at the same angle… ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [December 10, 2003, 12:51am UTC](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041/8 "2003-12-10T00:51:22Z")
In the second photo, there’s what appears to be a very faint band of colour running up near the left-hand end of the frame - I believe this is the secondary bow, concentric with the more curved of the two rainbows. The other one must be from a different light source; possibly something quite nearby, like a shiny tabletop or a window (rainbows that are actually very close (that is to say formed by nearby water droplets) can look as if they are quite distant) ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [December 10, 2003, 12:56am UTC](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041/9 "2003-12-10T00:56:04Z")
Once I was back on dry land there was a proper, and fairly spectacular, [double rainbow](http://www.geocities.com/robkingston/rainbows4.jpg) to be seen, behaving as it should - concentric and with colours reversed. That’s why I thought it might have been because I was still on the water when I saw the weird one. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [December 10, 2003, 1:00am UTC](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041/10 "2003-12-10T01:00:49Z")
Perhaps the light source for the second, non-concentric bow is the reflection of the sun from the water’s surface? ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [December 10, 2003, 1:04am UTC](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041/11 "2003-12-10T01:04:21Z")
Yep, that was my first guess (see OP), but I don’t really see how that would work… hmmm. I don’t think it could have come from the boat I was on at the time ([this one](http://www.geocities.com/robkingston/boat.jpg) 🆒 ) Anyway, time for me to get some sleep. I will await any words of wisdom from ray-tracing experts overnight… ---
**Author:** ![bughunter](https://avatars.discourse-cdn.com/v4/letter/b/aeb1de/32.png) [@bughunter](https://boards.straightdope.com/u/bughunter)\ **Post date:** [December 10, 2003, 2:37am UTC](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041/12 "2003-12-10T02:37:05Z")
It could easily happen if the sun was low in the sky behind you. Imagine this: ```auto sun # droplets ` you <) _______________________________________________________________________________________ Water ``` Now imagine what the view to the left from the position of the droplets would be. They’d see the sun, and a reflection of the sun from the water. And then, you’d get a dispersed reflection from both sources from the droplets… i.e., non-concentric multiple rainbows. Kudos for Mangetout for solving that one! ---
**Author:** ![Scarlett67](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/scarlett67/32/7387_2.png) [@Scarlett67](https://boards.straightdope.com/u/Scarlett67)\ **Post date:** [December 10, 2003, 12:38pm UTC](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041/13 "2003-12-10T12:38:08Z")
Mr. S once saw a TRIPLE rainbow. Three complete arcs. He says it was the most amazing thing he’s ever seen. ---
**Author:** ![Achernar](https://avatars.discourse-cdn.com/v4/letter/a/e274bd/32.png) [@Achernar](https://boards.straightdope.com/u/Achernar)\ **Post date:** [December 10, 2003, 12:52pm UTC](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041/14 "2003-12-10T12:52:43Z")
> [@](#): > > \*Originally posted by r\_k \* > My best guess is that a reflection of the sun in the water is also forming a rainbow, but I can’t really see why it would make that shape… Yes, that’s what it is. They’re called [reflected-light rainbows](http://www.pacarras.net/gm1/archives/00000142.htm). I actually first learned about them from [EPOD](http://epod.usra.edu/archive/epodviewer.php3?oid=108672). I agree with **bughunter** that you should send these in. ---
**Author:** ![CurtC](https://avatars.discourse-cdn.com/v4/letter/c/ce73a5/32.png) [@CurtC](https://boards.straightdope.com/u/CurtC)\ **Post date:** [December 10, 2003, 2:32pm UTC](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041/15 "2003-12-10T14:32:13Z")
I’d never thought about the possibility of a reflection rainbow, but agree that this could be the case here. The sharp, normal-looking rainbow is an arc of a circle whose center is below the horizon, so you can see it tilted sideways. But if the other is due to a reflection off the sea, its center would be an equal amount above the horizon, so that arc would be more vertical. And the secondary would be less sharp. The data seems to fit. ---
**Author:** ![Achilles](https://avatars.discourse-cdn.com/v4/letter/a/dc4da7/32.png) [@Achilles](https://boards.straightdope.com/u/Achilles)\ **Post date:** [December 10, 2003, 2:36pm UTC](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041/16 "2003-12-10T14:36:09Z")
We’re forever getting double rainbows in Ireland, what with the pissy weather and all. The second rainbow is supposed to displaced by 33.5 degrees from the primary rainbow… but all the way around. Your pics look like they taper in at the ends - this doesn’t happen with normal double rainbows… ---
**Author:** ![Achilles](https://avatars.discourse-cdn.com/v4/letter/a/dc4da7/32.png) [@Achilles](https://boards.straightdope.com/u/Achilles)\ **Post date:** [December 10, 2003, 2:37pm UTC](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041/17 "2003-12-10T14:37:15Z")
…make that 33.3 degrees… ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [December 10, 2003, 2:44pm UTC](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041/18 "2003-12-10T14:44:45Z")
Hey, thanks **Achernar**. That pic you linked to is almost exactly like what I saw, only their photo came out better. By the time I had got my camera out, the one I saw was already fading. Mystery solved, and my first guess was right 🙂 I was thinking about it this morning, and realised that the more vertical angle would make sense for a lower light source, as you would see more of the complete circle. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [January 1, 2004, 5:59pm UTC](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041/19 "2004-01-01T17:59:23Z")
They’re having a regular Dopefest over at [EPOD](http://epod.usra.edu/) lately. Yesterday it was **Thylacinewas taken** ’s [Pillar](http://epod.usra.edu/archive/epodviewer.php3?oid=170240), today **r\_k** ’s [Reflection Rainbow](http://epod.usra.edu/archive/epodviewer.php3?oid=170432). ---
**Author:** ![whiterabbit](https://avatars.discourse-cdn.com/v4/letter/w/cab0a1/32.png) [@whiterabbit](https://boards.straightdope.com/u/whiterabbit)\ **Post date:** [January 1, 2004, 7:12pm UTC](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041/20 "2004-01-01T19:12:30Z")
I once saw a triple rainbow – the third one was very faint but there was definitely something there. Quite a sight! [Next page](https://boards.straightdope.com/t/how-did-this-weird-rainbow-formation-happen-pics/218041.md?page=2)