The Bible tells us in Genesis that Noah, his family,
and all those animals bobbed around on endless waters for 40 days and 40 nights before the Lord finally drained off the flood and allowed them to return to firm land. He promised Noah and his descendants dominion over all nature and never again to visit upon them another flood.
And then the Lord set in the sky a mighty bow of brilliant colors. "This is the token of the covenant which I make between me and you and every living creature that is with you, for perpetual generations." He told Noah, "I do set my bow in the clouds, and it shall be a token of a covenant between me and the earth."
Long before Dorothy started her walk down the yellow brick road, rainbows have fascinated mankind. Perhaps no other natural phenomenon has so captured our imaginations as the rainbow. For thousands of years the rainbow has figured in legends and mythologies of nearly every known culture and artists throughout the ages have celebrated it in painting, poetry and prose.
Homer wrote in "The Iliad" that Aphrodite, wounded by the warrior Diomedes, fled the field of battle to Olympus along the rainbow bridge, carried swiftly by the goddess Iris. It was Iris, goddess of the elements, who in classical mythology charged the clouds with water from the rivers and lakes and thus benefited the farmer. In time Iris came to be the personification of the rainbow and the favorite patron of Greek and Roman farmers who paid her homage to her many shrines scattered about the countryside.
Ancient Babylonian mythology held the rainbow to be the financee' of the rain. The Mojave Indians of the American Southwest looked upon the rainbow as a charm sent by their creator to still the violent thunderstorms and calm the skies. Ancient Lapps saw in the rainbow the bow of their thunder god, who used it to shoot lightning bolts.

Six hundred years ago a German tradition insisted that before God would destroy the world, He would cause no rainbow to appear of 40 years; thus, medieval Germans gave thanks each time they saw a rainbow arch its way across a dark sky.
The "pot of gold at the end of the rainbow" that has long fascinated American children has it's roots in European folklore. It is but one of the many legends inspired by the inaccessibility of a rainbow's ends. An ancient French legend insists that a magic pearls lies at the end, waiting to be recovered by whoever is charmed enough to find it. Eastern European folklore says that angels use rainbows as slides and sometimes let drop little dishes that are especially effective in easing labor pains of expectant mothers.
But may primitive peoples fear the rainbow and look upon each appearance as a possible threat to their very lives. Some earlier Eastern European cultures saw the rainbow as a giant snake that drained water from river and lakes and sometimes sucked children on high. The myths of the Zulus in western Africa are full of horror stories of men and cattle swallowed by rainbows and never seen again. The people of many cultures believe that any house upon which a rainbow falls will suffer bad luck.
Other cultures give the rainbow different names. Italians call it "the flashing arch". In Sanskrit it is "the bow of Indra". North African tribes greet the rainbow as "the bride of God". For the Japanese it is "the floating bridge of heaven."
Superstition slowly has yielded to science. In 1637, Rene' Descartes, French philosopher and mathematician, postulated the first major scientific explanation of the refraction of light and formation of rainbows. Thirty-five years later, British scientist Sir Isaac Newton answered the age-old question of how the colors of the rainbows were formed. But what they and later scientists discovers only enhanced the wonder of the phenomenon. the science of the rainbow is as fascinating as its mythology.
Rainbows are often formed only a few hundred feet from the spectator. But the rain may not fill the sky over a wide enough area for a complete bow to develop. A rainbow is formed by two reflections and one internal reflection of light rays from the sun as they pass through falling raindrops. Sometimes a secondary bow, much fainter than the primary one, will appear inside the first. A rainbow is largest when the sun sits low on the horizon, so the best ones are found in early morning or late evening.

The higher the sun, the lower the bow. If the sun is above 40 degrees, no bow will appear. However, if you are "above" the sun, say on a mountain top or in an airplane, you will see rainbow as a perfect circle. Although the colored arc appears to lie in a two-dimensional plane, this is an illusion; in actual fact, it has great depth.
No two people ever see exactly the same rainbow. This is because two people, standing near one another and admiring a rainbow in the landscape, actually are seeing sunlight refracted and reflected by different sets of raindrops.
One of the advantages to being a rainbow buff is that you can see your rainbows almost anytime in any place. As Robert Greenler, a professor of physics as the University of Wisconsin and the author of the book "Rainbows, Halos and Glories", has observed: "Those of us who are hooked on rainbows see them in many places. The sprays from hoses, fountains, or waterfalls are obvious places to look. Other possibilities are the bow wave of a boat, the blown spray of a breaking wave, or a spray thrown up by the tires of passing cars on a wet road. You can see them where they lie trapped in the drops of dew on a lawn..or in the drops of moisture hanging from a spider web.
Few people know that the moon can create rainbows as readily as the sun, so most of us do not look for them on nights when a full moon shines through a light mist.

Nocturnal rainbows contain the same colors as the more familiar daytime rainbows but at such low light intensity that the eye does not detect them. However, the careful observer may glimpse these special rainbows - great bands of black and gray arching their way across the nighttime skies.
Black Rainbows!
Goodness! What would Dorothy have said about that?