A rainbow is one of nature’s most splendid masterpieces. Sometimes when the sun returns after some rain, we are treated to a brilliant and bright arc of color. Occasionally, if we are lucky enough, two rainbows will form in what is known as ‘The Double Rainbow’. The formation of one rainbow can easily be explained. What brings the second bow?
The formation of one rainbow requires two main ingredients, sun and rain. In order to observe a rainbow the sun needs to be at your back and rain falling in front of you. As light from the sun gets through the clouds and enters the raindrops the light bends in a process called refraction. This refraction occurs as slightly different angles for the different colored wavelengths creating a separation in the colors into what we refer to as a rainbow.
When a double rainbow forms, the first and bright rainbow is called the primary rainbow, while the second and fainter rainbow is called the secondary rainbow. This secondary rainbow is created when the refracted light does not escape the raindrop after being reflected the first time, and goes through a second reflection. This extra reflection causes the colors of secondary rainbow to be reversed compared to the primary one. Unfortunately, the secondary rainbow is not as bright as the primary one because fewer of the light rays are making it out of the drops and to your eyes. Brightness all aside it is truly a remarkable display of light put on by Mother Nature. After the next period of rain run out side and look to the sky, if you are lucky enough to catch a double rainbow, maybe you’ll be lucky enough to gets the two pots of gold that lie at the end.