The phenomena of light involved in the formation of a rainbow are refraction, dispersion, and internal reflection (or total internal reflection).
Explanation:
- When sunlight enters a raindrop, it first undergoes refraction as the light changes medium from air to water, bending the light.
- Inside the droplet, the light undergoes dispersion , which means the white sunlight splits into its constituent colors because different colors bend by different amounts.
- The dispersed light is then internally reflected off the back of the raindrop.
- Finally, the light is refracted again as it exits the raindrop, sending the separated colors to the observer's eye to form a rainbow.
These combined phenomena result in the circular color spectrum seen in rainbows.