Cloud formation is the process of creating clouds in the atmosphere. Stratiform clouds, also known as STRATUS clouds, are low-level clouds that form a continuous layer. Wispy clouds, or cirrus clouds, are thin and wispy clouds that are usually found at high altitudes. Mesa clouds, or cumulus clouds, are large, fluffy clouds that form in the middle atmosphere. VEE clouds, or lenticular clouds, are lens-shaped clouds that form when air is forced up and over a mountain range.