If the sky's blue comes from bouncing light, why aren't clouds blue too?
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After you watchIf the sky's blue comes from bouncing light, why aren't clouds blue too?
The short answer
Cloud droplets scatter the visible colors reaching them more evenly than tiny air molecules. White illumination can make a cloud look white; orange-red illumination at sunset can make it look orange-red.
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The whole story
How it works
The illustration holds droplet size fixed and uses the same input RGB mixture for the incoming and outgoing rays. It is a qualitative color model, not an angular Mie-scattering calculation. Large droplets scatter visible wavelengths more evenly; the spectrum and viewing direction of real cloud light also matter.
What people get wrong
A cloud does not always make white light. It scatters the colors available in its illumination.
The catch
Thick clouds with many stacked layers of droplets scatter light so many times internally that very little escapes from the bottom — making the underside appear grey or dark.
Questions kids ask
What color will this cloud scatter when only orange-red light arrives?
Cloud droplets scatter the visible colors reaching them more evenly than tiny air molecules. White illumination can make a cloud look white; orange-red illumination at sunset can make it look orange-red.
Talk about it
- What color will this cloud scatter when only orange-red light arrives?
- What stayed the same while you changed the control?
- Which part of the picture supports your prediction or challenges it?
For grown-ups
The illustration holds droplet size fixed and uses the same input RGB mixture for the incoming and outgoing rays. It is a qualitative color model, not an angular Mie-scattering calculation. Large droplets scatter visible wavelengths more evenly; the spectrum and viewing direction of real cloud light also matter.
Keep going
What else makes you wonder?
- Why do storm clouds look so dark and scary?
- How does a rainbow form if clouds just make white?
- Why do clouds turn orange and pink at sunset?
