by Konstantinos Kourtidis, Demokritus University of Thrace, Xanthi, Greece
A supernumerary rainbow is rather rare. It consists of several (in this image three) faint rainbows on the inner side of the primary rainbow. Supernumerary rainbows are slightly detached and have pastel colour bands that do not fit the usual pattern.
The faint rainbows are caused by interference between rays of light following slightly different paths with slightly varying lengths within the raindrops. Some rays are in phase, reinforcing each other through constructive interference, creating a bright band; others are out of phase by up to half a wavelength, cancelling each other out through destructive interference, and creating a gap.
The supernumeraries are more clearly visible when only the RED band of the original image is displayed; the RED-only of this image can be viewed at http://imaggeo.egu.eu/view/2599/ .
Taken on 17
Submitted on 02 September 2014
Credit: Konstantinos Kourtidis (distributed via imaggeo.egu.eu)
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