For those of us who've had the giddy fortune of seeing a double rainbow, apparently there's even bigger surprises in nature -- the quadruple rainbow.
Also called a "fourth-order" or quaternary rainbow, this rare and elusive phenomenon (along with "third-order" or tertiary rainbows) has only been reported a handful of times in the last 250 years. But a German meteorologist and amateur astronomer recently captured the first photo of this rare occurrence. Multiple rainbows are seen when light is refracted, dispersed and reflected multiple times inside a raindrop; twice for double rainbows and three for tertiary rainbows and so on.
You may be looking at the photo above and saying, hey, that's nothing but a double rainbow. But it is actually a tertiary and quaternary rainbow, and here's why, as explained by LiveScience:
The spectacle in the image looks like a double rainbow, because it only shows the third-order (tertiary) rainbow (left), accompanied by the fourth-order (quaternary) rainbow (right). They appear on the sunward side of the sky, at approximately 40 degrees and 45 degrees, respectively, from the sun. Tertiary and quaternary rainbows can only form on the same side of the sky as the sun, unlike primary and secondary rainbows. As such, the primary and secondary rainbows are on the other side of the sky and so not shown in the new photo.
Cool stuff. The photo above was taken by Michael Theusner, a meteorologist and amateur astronomer who answered the call to a "rainbow chaser challenge," issued by a professor of astronomy at last year's International Conference on Atmospheric Optics. Along with colleague Michael Grossman, the pair snapped this image during June this year, later published in Applied Optics.
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