I saw a rainbow outside Silverton, CO last week that for a few minutes seemed to show part of the color cycle (red to purple) several times within the same band. This picture is how it looked to my eye. I assume this is some refraction phenomenon of multiple rainbows, or ... ? It was also a double, but that part isn't shown.

showed this banding for a few minutes

I took another picture a few minutes later of it looking normal (the rainbow brightened, the droplets were bigger, and there was a strong double):

enter image description here

What is causing this strange banding?


1 Answer 1


It a supernumerary bow, which results when the droplets that create the rainbow are very small and of nearly uniform size. The droplets need to be small enough so as to make diffraction a significant effect.


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