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How does a rainbow form?
Quick answer
A rainbow forms when sunlight passes through raindrops, which bend and split the light into its colors. Each droplet acts like a tiny prism, separating white light into red, orange, yellow, green, blue, and violet, and reflecting them back to your eyes.
Step by step
- Sunlight enters a raindrop and bends (refracts).
- Different colors bend by slightly different amounts, spreading them out.
- The light reflects off the back of the drop and exits, split into colors.
- You see a rainbow with the sun behind you and rain ahead.
- It's always a circle, though the ground usually hides the lower half.
People also ask
Why does a rainbow have colors?
White sunlight is a mix of colors; a raindrop bends each color by a slightly different amount, fanning them out into the visible spectrum.
Why do you need the sun behind you to see a rainbow?
The drops reflect sunlight back toward its source, so you see the bow when the sun is behind you and the rain is in front.
Are rainbows actually circular?
Yes — a rainbow is a full circle of light, but the horizon usually blocks the bottom; from a plane you can sometimes see the whole ring.
What causes a rainbow?
Sunlight bending and splitting into colors as it passes through raindrops acting like tiny prisms.
Why is a rainbow curved?
Light reflects from drops at a specific angle all around, forming a circular arc centered opposite the sun.
Part of the guide: Water & Weather Phenomena →