Why are rain clouds usually grey, but normal clouds also filled with moisture are white?
In: Planetary Science
Rain clouds are white at the top. Thin clouds are white all the way through, but thicker clouds are so thick that less light makes it out the other side, so they tend to be dark at the bottom.
When the sun is very low in the horizon, it can illuminate even very thick clouds from below.
“Why is a lake murky, but when I take a glass of water from it, it’s clear?”
Basically, the water droplets scatter light. But they also absorb some. If you have a thin layer of it, you will do more scattering than absorbing, but the thicker it gets, the less light actually makes it all the way through. So they look grey.
If you’re inside the rain cloud, near the top, they’re white because they’re scattering light in all directions, including up.
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