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rainbow overload I

© All rights reserved (by me the photographer - Dr. David J. Otway)


We do get a lot of rainbows in Cork :-)


blow me down with a sausage - this made no. 5 on Explore for 19-11-07 - thx to you all !


If you look at this shot full size you can see a few faint supernumerary bands (esp the yellow/green one)


This was tough to capture as the clouds were moving at a serious speed (about 40 mph) and so the rainbows came and went very quickly.


More pics (same rainbow in fact just further up the bow) and yet more pics of supernumerary rainbows.


Info from the wikipedia on Supernumerary Rainbows: Infrequently, another beautiful and striking rainbow phenomenon can be observed, consisting of several faint rainbows on the inner side of the primary rainbow, and very rarely also outside the secondary rainbow. They are slightly detached and have pastel colour bands that do not fit the usual pattern. They are known as supernumerary rainbows, and it is not possible to explain their existence using classical geometric optics. The alternating 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. Given the different angles of refraction for rays of different colours, the patterns of interference are slightly different for rays of different colours, so each bright band is differentiated in colour, creating a miniature rainbow. Supernumerary rainbows are clearest when raindrops are small and of similar size. The very existence of supernumerary rainbows was historically a first indication of the wave nature of light, and the first explanation was provided by Thomas Young in 1804.


there is an even more indepth discussion of supernumerary bows at this most excellent site.


All three of these last shots are taken from our house in Co. Cork, Ireland (but not all on the same day!)

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Taken on August 20, 2007