What causes the rainbow?
The rainbow is caused by light from the sun (or moon) interacting with raindrops falling from the air. These raindrops are mostly round. A ray of light entering such a droplet is bent (refracted) and decomposed into all possible colors (wavelengths) which the white light consists of. The ray then reflects internally in the droplet, and emerges roughly into the direction it came from when it entered the drop. Since the rays of the different colors all exit at slightly different directions, you see a color band in the sky. • Why is the rainbow colored? The colors are produced by a phenomenon called dispersion. Dispersion causes white light, which consists of all possible colors (better: wavelengths or frequencies) to break up into all components, when the light travels from one medium (e.g. air) to another (e.g. water). The different colors of light have all slightly different directions, so if you look in a certain direction in the sky from which mostly some particular colored light com
