What are Clouds?

Clouds are made of water.  They are either small liquid water drops or tiny pieces of ice.  Meteorologists are scientists who study the weather.  They rank clouds by their height and whether they are flat or puffy.  The chart below is one way to remember clouds.
 
 

Clouds form when the air rises.  As a blob of air rises it expands and gets colder, the colder air cannot hold as much water as warmer air.  As the temperature and air pressure continue to drop, tiny water droplets group together into clumps called cloud droplets.  At this point, the blob of air becomes a visible cloud.  If the cloud keeps going up, the cloud droplets will clump together and form water droplets.  These water droplets are too heavy to float in the air and they fall from the sky as either rain or snow.  The word nimbus means rain cloud.
 

Types of Clouds

                                           Shape                 Weather