What does the rainbow refraction theory explain?

The rainbow refraction theory explains that as light enters a raindrop, it slows down and bends due to the change in medium from air to water. This process is known as refraction. Once inside the raindrop, the light reflects off the inner surface and undergoes dispersion, which means that the different wavelengths of light (colors) separate from one another. As the light exits the droplet, it refracts again, leading to the formation of a circular arc of colors that we see as a rainbow.

This theory highlights the crucial role of the raindrop's shape and the physics of light in creating the colorful arcs in the sky, particularly after rain when light has the opportunity to interact with water droplets. It is the mechanism of refraction and the resultant dispersion of light that produces the vivid spectrum of colors that are characteristic of rainbows.