These images are for non-profit Educational use only.
What are clouds?
Clouds are water. Either small liquid water drops or tiny pieces of ice. Meteorologists
rank clouds according to their height and whether or not they are flat or puffy. The graph
below is Dan's easy way to remember clouds.
Cumulonimbus (or Thunderstorm)
Nimbus means rain cloud.
There are some other specific types of clouds, some of which are very
rare. Visit Dan's Cloud Gallery by clicking on the images above or visit
Plymouth State College's "Cloud
for some fine examples and descriptions
of the many varieties of 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.