Double and supernumerary rainbows

Supernumerary rainbows (the additional cycles of color at the inside edge of the primary bow) are not commonly observed and occur only when the raindrops are all nearly the same size. Compare this supernumerary bow with a normal rainbow and you can easily see the difference for rainbows taken on the same day only a few miles apart near Paihia, New Zealand.

The darker region between the primary and secondary bows is called "Alexander's Dark Band" and arises due to raindrops preferentially scattering (refracting and reflecting) light from the sun backwards at angles inside the main bow and outside the secondary bow. Photoshop has been used to perform a few adjustments to this picture. First, the brightness was decreased and contrast increased to enhance the presence of the supernumerary bow. In addition, the guy and girl were turned in the opposite direction to face the rainbow and the pedestal was moved a bit to the right so the rainbow appears to be ending at it.

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Taken in August 1991