How does water vapor form clouds?

Question

i know that clouds are water vapor that has condensed....but where does the sun-blocking, visible form of water vapor known as clouds come from?

Answer 1

The air itself cools to below the dewpoint. But there actually are surfaces in the sky, very small ones such as dust and salt particles. They are critical to droplet formation. Without them, the moist air would have a very hard time condensing the water out. It would have to be cooled to well below the dewpoint before enough water molecules could get together to form a droplet. But once it did, golly gee that would be a sight because that highly subcooled droplet would suddenly be the surface that all the water would condense on, and it would get real big, real fast.

Answer 2

in order for something to condense they must have something which to condense on.  the water vapor condenses onto the the dust in the air and forms the cloud.