Why does the light dispersed by the raindrop appear as a bow ?

Explanation

A rainbow is not the flat two dimensional arc as it appears to us. The rainbow we see is actually a three dimensional cone with the tip of our eye. All the drops that disperse light towards us lie in the shape of the cone- a cone of different layers. The drops that disperse orange colour to our eye are on the outermost layer of the cone beneath the cone that disperse red colour. In this way the cone responsible for yellow lies beneath orange and so on it continues till to violet colour which the innermost cone.