[DoctorBeaver (OP)]

Clouds are made of water vapour, right? Water isn't grey or black so why are rainclouds those colours?

[another_someone]

I suspect this for the same reason that if you have white sheets on your bed, and you put your head under the sheets, the sheets (and all else) will look black.

[Batroost]

I suspect this for the same reason that if you have white sheets on your bed, and you put your head under the sheets, the sheets (and all else) will look black.

And there was me thinking it was because I hadn't washed them... [?]

[ukmicky]

Its firstly due to the height of the cloud and how much water vapour ,droplets etc there is in a cloud preventing the light from getting through and secondly as george said its our perception of dark against another shade of white.

[JimBob]

Water has no colour (note English spelling - I am Ethnically sensitive). What we see in the sky are the impurities around which water has changed phase going from a gas to a liquid (nucleation). It is the solid particles that cause the non-transmission of light, making rain clouds look dark. The diffusion of light from the nuclei in a less dense cloud (cumulus, cirrus, etc) is what cause the white clouds.

[neilep]

Hmmm..I'm not so sure.....next time you're up in am aeromobile look out the window with a  bit more attention to detail and focus !!

This is what I saw last time !!

[JimBob]

This is variations in lighting - diffusion and shade it appears.

[DoctorBeaver (OP)]

Water has no colour

It's blue  [^]

[JimBob]

Then How, dear sir, would it be possible to see the bottom of a spring-fed pool or what would be the point of building a glass bottom boat! If water were blue, all we would see is shades of blue and not little orange George the goldfish, swimming around in his aquarium.

(This is somehow off. I think I'll post after a little more coffee - or perhaps I'll roast some bancha tea and trip out on the caffeine.)

[Mornings are] the cruelest month. e. e. cummings

[DoctorBeaver (OP)]

Then How, dear sir, would it be possible to see the bottom of a spring-fed pool or what would be the point of building a glass bottom boat! If water were blue, all we would see is shades of blue and not little orange George the goldfish, swimming around in his aquarium.

(This is somehow off. I think I'll post after a little more coffee - or perhaps I'll roast some bancha tea and trip out on the caffeine.)

[Mornings are] the cruelest month. e. e. cummings

I've got a sneaky feeling the question of the colour of water was asked on TNS radio show a while back.
And here's a link for you http://webexhibits.org/causesofcolor/5B.html