Rainbows are usually seen soon after a summer rain. It happens when sunlight shines through raindrops which are still present in the air. Light, which appears to be white in colour, is actually a combination of colours like violet, indigo, blue, green, yellow, orange and red, which are not visible to the eye. When sunlight strikes the raindrops at a particular angle the sunlight splits into its component colours making them visible to the eye. These colours form an arc across the sky which is called the rainbow.