A rainbow is a meteorological phenomenon that occurs when sunlight is refracted, or bent, and reflected inside raindrops in the air. It takes the form of a multicolored circular arc in the sky. Rainbows are typically seen when there are rain showers or other sources of water droplets in the air, such as mist, spray, or fog.

The process of the formation of a rainbow begins when sunlight enters a raindrop. The sunlight is made up of different colors, each with a different wavelength. As the light enters the water droplet, it slows down and bends, or refracts, due to the change in the density of the medium. The different wavelengths of light are refracted by different amounts, causing them to separate and spread out.

Upon entering the droplet, the light is partially reflected off the inner surface of the droplet and then refracted again as it exits the droplet. This refraction and reflection within the droplet cause the light to undergo further separation and dispersion. The different colors of light then exit the raindrop at different angles, forming a circular arc of colors.

The most common type of rainbow, known as a primary rainbow, is the one that people are most familiar with. It displays a sequence of colors from red on the outer edge to violet on the inner edge, with orange, yellow, green, and blue in between. The primary rainbow appears as an arc, with its center opposite the sun in the sky. Sometimes, a secondary rainbow can be seen outside the primary rainbow, appearing as a fainter and wider arc. In the secondary rainbow, the colors are reversed, with red on the inner edge and violet on the outer edge.

Rainbows are not physical objects, but rather optical illusions created by the interaction of light with water droplets. They are observed from the observer’s perspective, so each person sees their own unique rainbow. The exact colors and intensity of a rainbow depend on factors such as the size of the raindrops, the angle of the sunlight, and the position of the observer.