Convection

Generally, it is the transport of heat and moisture by the movement of a fluid. In meteorology, the term is used specifically to describe vertical transport of heat and moisture, especially by updrafts and downdrafts in an unstable atmosphere.

The terms "convection" and "thunderstorms" often are used interchangeably, although thunderstorms are only one form of convection. Convection is not always made visible by clouds. Convection which occurs without cloud formation is called dry convection, while the visible convection processes are forms of moist convection