Precipitation

Weather

Precipitation

Where there is moisture and heat, there is evaportation. The heat makes the water evaporate and rise. Warm air can hold more water vapor than cold air, because it is less dense. As the air rises into lower pressure it cools because of energy and work. The water vapor creates clouds. When the air is cooled to its dewpoint it reaches saturation.

http://images.google.com/images?um=1&hl=en&q=rain&btnG=Search+Images

There are four basic types of clouds...

Cirro-form: usually composed of ice crystals
Nimbo-form: Nimbos means rain, brings steady precipitation
Cumulo-form: Show the vertical motion and thermal uplife of the air taking place. The lower the bottom of it, the higher the humidity.
Strato-form: latin for layer or blanket, brings gray and dull weather.

http://www.srh.weather.gov/jetstream/synoptic/clouds.htm

Before 1800 there were no official terms for all the different types of clouds in the sky. Luke Howard, an Englishman, who studied the clouds and eventually gave them these names.

http://inventors.about.com/od/britishinventions/a/clouds.htm