Great Barrier Reef Rainbow

November 05, 2010

Photographer: Leah Fiander
Summary Author: David Wigglesworth

Whenever you see a low-slung rainbow such as this, you can be sure that it was taken well after sunrise or well before sunset. My wife captured this bright primary rainbow from a small boat while traveling from the Great Barrier Reef back to Cairns, Australia. Rainbows have a radius of approximately 42.5 degrees and are centered on the antisolar point -- opposite of the rainbow. This picture was taken when the sun was approximately 30 to 35 degrees above the horizon, which means that the antisolar point was approximately 33 degrees below the opposite horizon. Therefore, the bow itself was about 10 degrees above the horizon (42.5 minus 33).

Note that the sky appears lighter within the arc of the bow than above it bow. This is because raindrops that exist within the “cone” of the bow (that is, the cone from our eye to the edge of the virtual bow) are also reflecting sunlight back to the viewer, however, the colors are overlapping. Thus, we're unable to see specific colors near the middle of the primary bow -- we only see “white light.” Photo taken on September 13, 2010. Compare this bow with the high arching beauty taken by Riccardo Di Nasso from Pisa Italy, also on September 13.

Photo details: Camera Maker: NIKON CORPORATION; Camera Model: NIKON D70s; Focal Length: 34.0mm (35mm equivalent: 51mm); Aperture: f/11.0; Exposure Time: 0.0020 s (1/500); Exposure Bias: none; Metering Mode: Matrix; White Balance: Auto; Light Source: Unknown; Flash Fired: No (Manual); Color Space: sRGB.