Types of Clouds  
  Cirrus are high wispy clouds made up of ice crystals. Cirrostatus and cirrocumulus are types of cirrus clouds.  
  Cumulus clouds are bright white, fluffy and round. They indicate fair weather. Over time they may develop into storm clouds. Altocumulus and stratocumulus are just cumulus clouds at higher altitudes with a greater potential to bring bad weather.  
  Cumulonimbus clouds are thunderclouds. They are sometimes called thunderheads and are known by their anvil like shapes. These clouds are often accompanied by high winds, thunder, and lightning. Think of them as "super" cumulus clouds.  
  Stratus clouds are thick, gray, low-altitude layers that usually bring light rain or fog. They like to spread outward in sheets and sometimes cover higher ground.  
  Nimbostratus clouds are low altitude versions of stratus clouds. They often mean bad weather such as fog, snow, or rain.