Why is the sky always darker above a rainbow, than below it? 🌈

Question

I’m looking at one right now.

In: Physics

Answer 1

A rainbow lines up with you and the sun. If you were in the air above a waterfall, for example, you could see a complete ring.

The water droplets inside the rainbow act like a mirror and reflect light back at you. As you move outward through the rainbow, the light is hitting the drops at an angle, relative to you, so it acts like a prism and refraction the light.

The light that hits the water outside the rainbow is reflected away from you.