A Kauai Rainbow
September 08, 2006
Hawaii is known as the Rainbow State and for good reason. On this mid ocean island chain, frequent rain showers and plentiful sunshine produce rainbows at every turn it seems. On a recent trip to the Islands this past winter, my wife and saw rainbows on every one of the three islands we visited over a two-week period! The photo above shows a gorgeous double rainbow taken late in the afternoon on February 2, 2006 -- on the east coast of the island of Kauai (at Kapa’a).
The primary bow is the much brighter of the two bands. Notice that the secondary bow is not only always fainter (partially because it's spread over a larger area), but it's colours are also reversed from those of the primary bow. The darkened area between the bows is called Alexander’s Dark Band, a phenomenon first described by a Greek, Alexander of Aphrodisias, in 200 AD. Not all of the sunlight passing through raindrops is reflected back toward our eyes. Much of the light between the angles of 46 and 51 degrees is scattered from our view, and thus the sky in this area appears relatively dark.