Couldn't Find the Pot of Gold

click to enlarge
Large Rainbow
Rainbow During Severe Storm
Orland Park, Illinois
October 18, 2007

A very warm, windy October day ended with severe storms in parts of the Chicagoland area. Temperatures reached 79 degrees (that's warm for October!) and an approaching cold front produced heavy winds, storms, hail and a terrific double rainbow.

Light passes into a raindrop and is refracted back to the opposite side and then again until it leaves the raindrop. The "bending" of the lightwave causes different wavelengths of light (or different colors) to exit at a slightly different angle thus producing the colors of the rainbow.

The inside of a rainbow is brighter than the outside because rainbows are actually discs of light, not narrow bands, so the interior of a rainbow is quite bright. Occasionally, a double rainbow can be seen. The outer band is called Alexander's Bow and displays the colors in the opposite direction as the primary bow. You can see a little bit of a second band in the photo here. Note the the space between the two rainbows is much darker than the inside, this is called Alexander's Dark Band.

click to enlarge
double Rainbow

Rainbows are best spotted just after sunrise or just before sunset. The low angle of the sun produces a rainbow that "touches" the ground on both sides. Actually, a full circular rainbow can be seen from an airplane.

Every rainbow is unique to the viewer. In other words, the rainbow you see is actually completely different from the rainbow observed by the person next to you.

This is probably the last rainbow of 2007 for us in Chicago, but the way the warm weather has been sticking around, maybe we'll have one for Christmas.

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