thundercloud

A thundercloud is a common name for a cumulonimbus cloud, a tall, dense cloud associated with thunderstorms. It forms in an unstable atmosphere when warm, humid air rises rapidly due to convection. As air ascends, condensation releases latent heat that fuels further vertical growth, often creating a cloud that extends from near the surface to the upper troposphere.

Cumulonimbus clouds exhibit strong vertical development and a characteristic anvil-shaped top when upper-level winds shear the updraft into a broad, flat cap. They contain strong updrafts in the mature phase, allowing hail formation, and downdrafts that bring in cold air and heavy rain. The base is typically dark and may be a precursor to heavy precipitation.

The life cycle includes a developing stage, a mature stage with intense precipitation and electrical activity, and a dissipating stage as the updrafts weaken and dry air entrainment suppresses the cloud. Lightning and thunder are common features; thunder results from rapid heating and expansion of air around a lightning channel.

Thunderclouds commonly form along cold fronts, squall lines, or warm, humid air masses in daytime heating. They can produce severe weather including strong winds, heavy rainfall, hail, and occasionally tornadoes. They are monitored by weather radar and satellite observations to assess potential hazards and warnings.