Rainbows form when sunlight interacts with water droplets through a process of reflection and refraction. The process occurs in several steps:
- Sunlight enters a water droplet and is bent (refracted)
- The light is reflected off the back of the droplet
- As it exits, different wavelengths separate into distinct colors
- Multiple reflections can create double rainbows
Rainbows always appear opposite the Sun from the observer’s position and require both sunlight and water droplets in the air. The classic rainbow colors (ROYGBIV) appear in a consistent order due to different wavelengths of light being bent at slightly different angles.