Without quoting directly from the text, tell me about rainbows.

Rainbows may appear when light passes through water. When a rainbow appears when it's raining, it's always in the opposite direction from the Sun. Although usually in the form of an arc, rainbows can also be full circle. The colors on the primary and double rainbows are inverted with red appearing on the outer part of the primary rainbow and the inner part of a double rainbow.