Clouds turn black from white or blue when it rains.

A cloud is a group of ice and water macromolecules.

After the Sun's heat boils the water in water bodies, the steam goes up.

These small molecules of water are the 100th part of a millimetre, and because of the cold atmosphere, it starts freezing.

These molecules are in a volume of 100 million pieces of water in a cubic metre of air.

Because of their smallness, they keep floating in the air at -31 degrees in liquid form.

Shining Sun makes them look white like wool.

The density of the clouds increases due to the volume of the water.

When that happens, Sunlight can't penetrate the clouds, Which is why they look black.