Continuing press for triple and quadruple rainbows

The media attention continues for the recently published triple and quadruple rainbows… this time in “The Times” of London.
http://www.thetimes.co.uk/tto/life/courtsocial/article3192375.ece

Weather Eye: the triple and quadruple rainbows
Paul Simons
October 13 2011 12:01AM 

A rainbow is a wonderful sight, and a double rainbow even more so. But a German photographer has taken rainbows to a new dimension — he has captured both triple and quadruple rainbows.

On June 11 Michael Theusner was watching a thunderstorm approach his home town of Schiffdorf, near Bremerhaven in northern Germany. “I went to a field road by car to take some photos of the storm clouds. Just after I had arrived, about 6pm, heavy rain started . . . I waited and hoped that the Sun would come out soon and produce some nice rainbows. When it did, I realised that the dark clouds covered the sky to the right of the Sun.” And those dark clouds beside the Sun gave exactly the right backdrop to catch the elusive third and fourth rainbows, later revealed with sophisticated photo processing and which can be seen at http://bit.ly/nXmqQZ.

According to the Optical Society in the US, there have been only five scientific reports of triple rainbows in 250 years, and none of the quadruple bow. In fact, some scientists said that both types of rainbows were a myth. It is easy to see why they remained so elusive because primary and secondary rainbows are easy to see as they light up the sky away from the Sun. But tertiary and quadruple rainbows form close to the Sun, where the intense glare of the Sun makes them extremely difficult and dangerous to see. They only start to become apparent against a dark background of thunderclouds with a heavy downpour, or a shower of nearly uniformly sized raindrops. Even then, a filter is needed to cut out the Sun’s glare and photo processing needed afterwards because the bows are very faint.

Although very rare, the extra rainbows are created in just the same way as normal rainbows, by sunlight refracting and reflecting inside raindrops before beaming out into an arc generic for cymbalta. A triple rainbow forms when the light rays are reflected three times inside the raindrops, and a quadruple bow has four internal reflections, although its colours are reversed and the bow is even fainter.

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About Joe Shaw

Joseph Shaw is Director of the Optical Technology Center and Professor of Electrical Engineering, Optics, and Physics at Montana State University in Bozeman, Montana. He loves to photograph, study, and teach about optical effects in nature. His PhD is in Optical Sciences from the University of Arizona.

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