Rainbow
A natural phenomenon sometimes visible in the sky, when light from the Sun interacts with water droplets in the Earth’s atmosphere. The range of hues we see in a rainbow comprise the visible spectrum.
Rainbow seen in The Trossacks, Scotland. Image courtesy of Stephen Green-Armytage http://www.stephengreenarmytage.com/photographs/?category=28&print=277.
See also spectrum and non-spectral hues.
