Rainbow formation physics

Rainbow formation involves all three optical phenomena: (1) Refraction: Sunlight bends when entering and exiting water droplets (different refractive index of water vs air). (2) Dispersion: White light separates into different colors because each wavelength refracts at slightly different angles in water. (3) Internal reflection: Light reflects internally off the back surface of the water droplet before exiting, with primary rainbow involving one internal reflection. All three phenomena work together: sunlight refracts entering droplet → disperses into spectrum → internally reflects → refracts again exiting. Without any one of these, rainbow formation would not occur. Each is essential to the complete rainbow phenomenon. > Process sequence: Refraction (entry) → Dispersion (color separation) → Internal Reflection (bounce) → Refraction (exit) = Rainbow.