Rainbows are beautiful bursts of color in the sky, which are usually seen following a rain shower. They are a natural phenomenon that has mystified people for centuries. No matter how old you are, it is always fun to see a rainbow appear in the sky. The arch of light is separated into several bands of color that always occur in the same order. Sometimes, though, a rainbow might begin and end with a different color. For instance, you might see only the orange, yellow and green, or the red, purple, and blue portion of the rainbow. A full rainbow includes red, orange, yellow, green, blue, indigo, and violet.
How the Color is Created
The colors of the rainbow are produced by dispersion. White light passes through a prism and scatters, causing it to be seen as different colors. It is dispersion that causes a rainbow to be visible in the sky. Drops of water (rain) form in the atmosphere and the light of the sun moves through these droplets, which are acting as the prism. As the light enters the droplet, the light is bent and scatters. The colors are reflected off the back of the droplet of water and redirected back through the front side of the droplet. The angle of the bending light creates the colors of the rainbow.
A rainbow is always be opposite from the sun, so someone facing the rainbow will have their back to the sun. Rainbows are rarely seen unless the sun is low in the sky. This makes early evening a more popular time to see rainbows. The droplets of water are actually moving through the atmosphere and what you see in the rainbow is moving water, although it does not appear to be moving to the naked eye.
Rainbows are Circular
Rainbows appear in the sky as an arched shape, but are actually a circle. The angle of light is usually about 42 degrees, which corresponds with the sun’s level in the sky. The angle is large, so it is usually only possible to see a portion of the circle because the horizon cuts the lower part of the arch. When the sun is lower in the sky, more of the rainbow is visible. Those who want to view the rainbow as a complete circle can do so from a high altitude location.
There is such a thing as a double rainbow, which is considered lucky to those who are superstitious. Double rainbows occur when a second rainbow appears just outside of the primary rainbow. The second rainbow is parallel to the main rainbow and is caused by the sun’s light waves reflecting twice inside of the water droplets before emerging as color. The second rainbow in a double rainbow is usually not as bright as the primary rainbow.
Rainbows usually appear before or after a rain shower, but you might see a rainbow at other times without any rain. This is because there can be water in the higher levels of the atmosphere that never materialize into rain. Ancient cultures believed rainbows were a sign it was about to rain heavily, but this was not always accurate.