What is Rainbow?
{{for|the English hard rock band|Rainbow (band)}} [[File:Радуга над вулканическими конусами.jpg|thumb|A rainbow over the 1975-76 Tolbachik eruption: [[Kamchatka Krai]], [[Russia]]]] [[Image:Nashi pear tree in bloom.jpg|thumb|220px|A rainbow near the Nashi [[pear tree]] in the bloom]]A '''rainbow''' is an [[arc]] of [[colour]] in the [[sky]] that can be seen when the [[sun]] shines through falling [[rain]]. The pattern of colours, called a [[spectrum]], starts with [[red]] on the outside and changes through [[Orange (color)|orange]], [[yellow]], [[green]], [[blue]], [[indigo]], and [[Violet (color)|violet]] on the inside. Sometimes a second, larger, dimmer rainbow is seen. A rainbow is created when white light is bent ([[refraction|refracted]]) while entering a droplet of water, [[dispersion|split]] into separate colours, and [[reflection|reflected]] back. A rainbow is actually round like a circle. On the ground, the bottom part is hidden, but in the sky, like from a flying airplane, it can be seen as a circle around the point opposite the [[Sun]]. Rainbows often appear after [[storm]]s, and are popular symbols for peace in many [[culture]]s. == Cause == The rainbow effect can be seen when there are [[water]] drops in the [[air]] and the [[sun]] is giving light at the back of the observer at a low distance up or angle. Rainbows always appear opposite the [[Sun]]: they form circles around the shadow of your head (which is the point opposite the [[Sun]]). While [[sunlight]] is [[white]], all white light is actually a blend of many different colours. [[Water]] and other materials bend the different colours at different angles, some more strongly than others. This is called [[dispersion]]. By splitting up white light into its separate colours, rainbows appear colourful even though the source of light hitting them is [[white]]. The rainbow displays with the deepest effect in our minds take place when: * Half of the sky is still dark with draining [[cloud]]s; and * The observer is at a place with clear sky above