Rainbows are one of nature’s most beautiful optical illusions
WHEN DO RAINBOWS OCCUR?
Rainbows only occur when the Sun is low in the sky and behind the viewer, shining at just the right angle into air full of water droplets, such as a rain shower. When sunlight shines into a water droplet, it exits it at different angles depending on its different wavelengths. This is called refraction and it splits up the light into its rainbow colors.
What Are The Colors In A Rainbow?
Orange and red colors are always on the outside, green, blue and purple on the inside. For double rainbows, the second rainbow will be further out with colors reversed because of a double reflection within each water droplet.
How is a Rainbow Created?
Here is a schematic view of how a rainbow is created. It illustrates that you have to be at the exact right position with respect to the Sun and the water droplets in order to see a rainbow.