Part 2/6:
To understand this, envision a raindrop as a spherical object in which light rays enter, bend, and reflect. The light that strikes the drop is refracted, or bent, at an angle before it reflects off the back inner surface of the drop and exits, returning to the observer’s eye in a spectrum of colors.
Refraction and Snell’s Law
The mathematics of rainbow formation largely stems from Snell’s Law, which governs how light bends when it moves between different mediums. The law states that the sine of the angle of incidence (the angle light hits a surface) divided by the sine of the angle of refraction (the angle light bends) is a constant and can be expressed mathematically:
[ \sin(\alpha) = k \cdot \sin(\beta) ]