Reflected Light Rainbow

January 01, 2004


Referred by: Rob Kingston
Summary authors & editors: Jim Foster; Rob Kingston

Uh, un, un! Wouldn't this be a nice way to start off the new year; a tranquil lagoon, swaying palms, tropical breezes, and even a rainbow. However, this isn't "just" a rainbow, it's a reflected-light rainbow. The near-vertical shaft to the left of the primary rainbow is caused by the reflection of the Sun in the water. It was taken from a small boat on the lagoon shown above, just off the island of Aitutaki (Cook Islands), as a rain shower paid a brief visit on an otherwise sunny day. Back on dry land, a few minutes later, a spectacular double rainbow was visible.

The reflected-light rainbow is produced when light from the Sun reflects off a smooth body of water and into the sky at a higher angle than the sunlight responsible for causing the primary rainbow. Essentially, the mirror-like reflection of sunlight from the lagoon interacted with cloud droplets to form the steeper bow at left. You can tell that this bow is a reflected bow and not a secondary rainbow since the color sequence is the same as that of the primary bow.

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