www.weather.gov RAINBOW
Many times after a passing shower, we are amazed by the vivid display of color
-a rainbow. Rainbows have shown great significance to many cultures since the
beginning of time. The most well known legend is that one will find a pot of
gold at the end of the rainbow; this is an old European tradition. Yet in some
African mythologies, the rainbow is signified by a giant snake that brings bad
luck to the house it touches. The scientific explanation for rainbows came about
in the 17th Century with discoveries by the famous scientists, Rene Descartes
and Sir Issac Newton.
Rainbows are formed when raindrops, acting like a prism, reflect sunlight toward the observer, dispersing the light into colors. As light enters a water drop, different colors bend at slightly different angles. Some of the light reflects off the back of the drop and is bent again as it emerges. Drops at different angles from you send different colors to your eye. If the light is hitting the rain drop at the proper angle, a secondary, larger rainbow will form outside of the main rainbow. This secondary rainbow is fainter then the main one because the light is reflected twice by each raindrop. This also reverses the colors of the secondary rainbow.
To see a rainbow, you must
be standing with the sun at your back and rain must be falling in another part
of the sky. Each raindrop lit up by the white light of the sun produces a spectrum
of colors. No two people ever see exactly the same rainbow. Each observer views
a different set of drops at a slightly different angle. In other words, each
color you see is coming from different rain drops.
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