A rainbow is an optical phenomenon that involves the most spectacular display of an array of light in the sky. The fabulous spectrum of light in the sky is visible to an observer when the sun's rays fall on the raindrops or droplets of water within the earth's atmosphere. The rainbow appears when the sunlight gets dispersed in the atmospheric moisture and then gets refracted twice. Thus the rainbow becomes the distorted reflection of the sunlight in the droplets of water. Thought it seems like weather illusion , it is actually a natural phenomenon.

Since yore rainbows have been an object of fascination for people of all ages. The meteorological phenomenon of the rainbow was not properly known to mankind for long and it was considered as one of the wondrous occurrences in nature. In ancient Greek mythology, it was considered that the rainbow was created by a messenger named Iris as a passageway between the Earth and Heaven. In Hindu mythology, the rainbow is regarded as the bow of Lightning and Thunder God- Indra .

Rainbows are particularly observed during the time of sunshine and falling rain. The best time to see them is during early morning or late afternoon when the sun is low because the arc is higher at these times. The rainbows are always positioned just opposite the sun and their centres lie below the horizon. An observer can see the multi hues within an arc when there is moisture in the air and sunlight shines on it from behind at a low angle.

The outer curve is colored red while the inner arc is violet colored. The colors within the inner bow consist of yellow, orange, blue and green. Sometimes numerous arcs of purples, pinks and electric green are formed outside the main arc when raindrops are smaller. Sometimes there are also rare occurrences of lunar rainbows or a moon bows on lucent moonlit nights.