[header] How to distinguish the different types of clouds [title] Identify clouds by shape. [step] The two shapes are cumulus and stratus : [substeps] Cumulus clouds: these are the big, " fluffy " clouds that look a bit like cotton balls. These clouds have a thickness that is usually equal to or greater than their width and they have very distinct edges. 
Cumulus clouds tend to indicate that the atmosphere is unstable at the altitude where they are found. Stratus clouds: these clouds are layered and often look flat.