- storm clouds
These mammatus storm clouds looked pretty ominous, but they just brought heavy rain. These kinds of clouds often occur after a thunderstorm. For more information on the formation of these clouds, see: Mammatus clouds
Tornado clouds are often an eerie green. It is important to know the difference between a storm watch
and a storm warning
. A storm watch
means that conditions are favorable for a storm; a storm warning
means the storm has been spotted.