A rainbow is refraction, or bending of light. When the light bends it changes directions, and causes different wavelengths to bend differently. The sun’s rays enter the group of raindrops and the light bends off the edge of the drop back to our eyes.

Rainbows are caused when white light (sun light), enters a big group of raindrops. Light white light that enters the drops, refracts and the white light distributes and creates the rainbow we see in the sky.