A rainbow is an optical illusion that occurs when the sun's rays shine through moisture in the air, such as the moisture left over from a recent rain storm or shower. To understand what is happening to the light provided by the sun once it hits the water in the atmosphere, we must turn to terms we most likely learned in seventh grade science class: refraction and reflection, refraction being the bending of light and reflection being the bouncing back of light. Okay, so once the sunlight hits the particle or drop of water it is refracted or bended, then it is reflect through the back of the particle, and then refracted a final time. Through this bending and bouncing of light, the different angles created provide the spectrum of light we see as the rainbow in the predictable pattern of Roy G Biv: red, orange, yellow, green, blue, indigo, and violet.
Now, that's the first rainbow. At times, a subsequent rainbow – the elusive “double rainbow” -- is formed on the outside of the first and in the opposite order of colors as the primary rainbow. This happens because the sunlight is reflected through the drops of water twice, with the second reflection coming at a different angle. The second rainbow will be lighter than the first for two reasons. The first reason is that the rainbow is on the outside of the brighter rainbow, and therefore is traveling a greater distance across the sky. Secondly, more light has broken away from the drops of water with the second reflection than the first.
Ultimately, that is the scientific explanation behind the phenomena of the double rainbow. In order to get the effect, two things must be present: water and light. Perhaps the most convenient way to purposefully create a double rainbow is by spraying an arc of water from a water hose through the air on a sunny day.
Posted 3470 day ago