Question: Why are clouds formed in different shapes?

Susan Cartwright answered on 17 Jun 2015:

Clouds form when water droplets condense out of the atmosphere, usually because the air has become cooler. The different shapes happen because this cooling can happen in different ways. Little fluffy clouds (cumulus) often form at the top of rising columns of warm air (thermals) from warm spots on the ground, which can be caused, for example, by the presence of a factory in otherwise open countryside: as the hot air rises, it cools, and eventually the water condenses to form a cloud. Other types of cloud form when warm and cold air flowing around weather systems meet, or if air is forced up over a hill, or if you have a wind which is not stable in strength or direction (turbulence). Aircraft contrails are basically artificial clouds formed by turbulence coming off the aircraft body, for example.