Why are rain clouds dark?

I dunno

But we can't see through to the bottom of the ocean... how a wave turns whitish when it breaks on the shore.. or how the steam vapor from a tea kettle is white and opaque.. Water in clouds is a suspended, very fine mist or vapor that is constantly in turbulence, even if the outside of the cloud looks still and fluffy. When water is in motion, perhaps billions of droplets in motion against each other, combined with any sort of grit, pollen etc., it could make a cloud look dark and opaque. Yes, they are "just" vapor, but there are countless water bits/particles in a cloud that prevent us from seeing through them. When all of the particles of mist join together and become heavy enough to drop from the cloud with the pull of gravity, then that's your rain 'drop'. I always love how things can turn from one state to another, like going from a gas (water as steam) to a solid (water as ice), sometimes without going through the middle state of being a liquid..

Hello :) Here is a link to explain it in more detail than I do, but basically it has to do with the fact that the rain clouds are thicker/heavier than fair weather clouds, and don't let the sunshine through like fair weather clouds do >>>

http://www.abc.net.au/science/articles/2011/04/21/3196689.htm

When I was in grammer school, I vividly remember learning the names of the different cloud formations and the names of them were the spelling words for the week. Also again in 8th grade science class. Do you want to be a Meterologist? Here is a link that explains it better than I can.

https://www.livescience.com/39069-why-are-rain-clouds-dark.html

Or to learn more, you can just Google - "why are rain clouds dark" then check out the links.