Stratus are basically flat clouds that form along a certain altitude, making them look “stratified”, and are low in the atmosphere, often not far above the ground. read more
But when atmosphere instability get huge, runaway settles, ans a cumulus grows as congestus (a massive bulged cumulus), then the bulge rise as a column up to stratosphere roof (12km above floor) and splatch there, making the anvil shape. read more
As nouns the difference between cumulonimbus and cumulus is that cumulonimbus is a cloud, with a tall structure and a flat base, that is often associated with thunderstorms while cumulus is a large white puffy cloud that develops through convection on a hot, humid day, they can form towers and even become cumulonimbus clouds. read more
Cumulus clouds are those that take a vertical form, such as fluffy fair weather clouds, or Cumulonimbus, (thunderstorms). However, there isn’t necessarily a difference between Cirrus and Cumulus clouds, because Cumulus clouds may form at the Cirrus level of the atmosphere, and then be known as Cirrocumulus. read more