Why are clouds white?

Staring in the sky on a cloudy day (provided the weather is okay) you are going to wonder why the clouds are white. This may seem like a sentimental question to ask yourself but there is lots of science behind this question.

When you see water it is colourless. But when you see a cloud it is white. Suppose you go up in the mountains and stand 10-15 meters away from a cloud then you are going to see that it is purely white when you go further up...BOOM! You are in the middle of transparent stuff.

Why does this happen? This is why... Normally water is transparent but when layers of water vapour pile up they look like it is white. As an example take cling film. A piece of cling film in almost completely transparent but as you keep on folding it, it will slowly become translucent and then opaque. Same is with soap studs. They are individually transparent but when they are kept with hundreds of others they look very much white.

Now why white out of all the colours. Well because white is all the colours. If you mix all the colours you get white. Normally water and bubbles (soap) help the dispersion of light but when kept collectively in front of a light source, you are going to find that they act together and mix all the colours of the light spectrum up.