Capping inversion

A capping inversion is an elevated inversion layer that caps a convective boundary layer.

The boundary layer is the part of the atmosphere which is closest to the ground. Normally, the sun heats the ground, which in turn heats the air just above it. Thermals form when this warm air rises into the cold air (warm air is less dense than cold air), a process described by convection. A convective layer such as this has the potential for cloud formation, since condensation occurs as the warm air rises and cools.