Why are rainbows curved

The multicolored pattern of the rainbow is so overwhelmingly beautiful that the incorrigible questioning tendency of humans gets checked, at least for some time. Inquisitive as man is, the investigations as regards the formation of the rainbow have already taken place. The dissection has given mankind quite a few answers to the mysteries of the vibrant rainbow patterns.

It is indispensable to understand the basic recipe of a rainbow in order to grab the gist of its peculiar curvature. Though it harbors multiple shades, there are just two basic ingredients of a full fledged rainbow — water droplets suspended in the sky, and adequate sunlight. A water droplet is a lot more than just an integration of two atoms of hydrogen and one of oxygen. Deep inside, it has the apt optical circuitry to act as a prism. Just like a prism, a water droplet receives light at its front, allows it to barge into its back, and then reflects it back through the front in the form of a multi-colored band. After rainfall, a blanket of raindrops forms in the sky. When situated at an appropriate height, and in presence of sufficient sunlight, the droplets’ blanket reflects light from each drop separately, at the corresponding angles at which the droplets are suspended in the sky. Those at too high an altitude fail to exhibit any visible color pattern, and this inefficiency is also associated with those situated at too low a height. However, those at an appropriate height do the necessary reflection and create the rainbow pattern.

The relatively higher placed droplets create red hues, and the relatively lower ones give off shades of orange and its derivatives. The relative angle at which the reflection takes place creates the unbelievably well sculptured curvature of the rainbow. Sometimes, light may undergo double reflection inside the spherical water droplets. In such a scenario, a breathtaking pattern of dual rainbows decorates the sky. It is also important to realize that we would have observed a filled semi-sphere pattern of the rainbow, were it not for the fact that there is lesser rain near the ground surface and hence, the pattern gets fainter as we go downwards.