Altocumulus are the classic cotton ball clouds. These puffy, white clouds are the most common mid-level clouds and sometimes signal that a storm is on the way. The type of cloud that looks like a cotton ball is a cumulus cloud. This type of cloud is white and puffy, often scattered throughout an otherwise blue sky. Cumulo-form are detached clouds, that sometimes look like white fluffy cotton balls. They show vertical motion or thermal uplift of air taking place in the atmosphere. They are usually dense in appearance with sharp outlines.