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Q & A: Does raindrop motion affect rainbows

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Most recent answer: 03/11/2013
Q:
Since a water droplet is in motion, how does a spectrum get stability to form a rainbow?
- Utkarsh (age 16)
India
A:
Hi Utkarsh,

Great question! I'd never thought about that before.

But if you think about it, light in water travels at ~220,000,000 m/s, while a raindrop is traveling at ~10 m/s. So in the time the light crosses a raindrop, the drop falls less than 1nanometer!

Compared to sunlight, a raindrop is basically stationary. Although the light is dragged along with the raindrop somewhat, it doesn't cause any noticeable effects.

David

(published on 03/11/2013)

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