Clouds are condensations of water and other particles in the atmosphere. Cloud shapes—and the dynamics of their formation—are accurate indicators of important atmospheric properties, including air stability, moisture content, and motion.

Clouds are divided into families of high level, middle level, low level, and vertically developing clouds, and are classified again, in accord with their general shape (e.g., cumuliform or stratoform)

High level clouds include cirrus, cirrostratus, and cirrocumulus clouds that occur at altitudes between 16,000 and 45,000 feet. Middle level clouds include altostratus, altocumulus, and nimbostratus clouds that occur between 6500 and 22,000 feet. Low-level clouds include stratus and stratocumulus clouds that occur between the surface and 6,500 feet. Vertical development clouds include cumulus and cumulonimbus clouds, and range in their development from the surface to 45,000 feet. The heights of the bases of the clouds used to designate cloud families can vary with...