02 January 2012

A "reflection rainbow" - not a double rainbow

I have seen innumerable rainbows in my life, but have never seen this phenomenon. 
Phil Thompson was walking along a jetty at the Bellarine Peninsula in Victoria, Australia, when he spotted a rainbow reflecting off the sea to create two visible arcs of colour emanating from the same spot.
In the traditional double rainbow, the two arc would have he same radius of curvature.  The reflection phenomenon is explained at Wikipedia:

Where sunlight reflects off a body of water before reaching the raindrops (see diagram), it may produce a reflection rainbow (see photo at the right), if the water body is large, quiet over its entire surface, and close to the rain curtain. The reflection rainbow appears above the horizon. It intersects the normal rainbow at the horizon, and its arc reaches higher in the sky, with its centre as high above the horizon as the normal rainbow's centre is below it. Due to the combination of requirements, a reflection rainbow is rarely visible.

Six (or even eight) bows may be distinguished if the reflection of the reflection bow, and the secondary bow with its reflections happen to appear simultaneously [example below, from Norway, posted at APOD]:

Top photo: Phil Thompson / SWNS.com, via The Telegraph.  Lower photo: Terje O. Nordvik.

3 comments:

  1. Nit picky (what would the web be without it!) - a traditional double rainbow does not have arcs of "same radius of curvature" but all the arcs are concentric. If they had the same radius of curvature, they would intersect.

    The other difference in a traditional rainbow is the order of the colors in each arc. The even arcs have the opposite coloring from the odd arcs.

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  2. because someone had to say it:

    someday we'll find it
    the rainbow reflection
    the lovers, the dreamers and me

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  3. This is awesome and thank you for sharing! Love your blog and Happy New Year to you!

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