Direct cell

From Glossary of Meteorology

direct cell

(Also referred to as direct circulation.) A closed thermal circulation in a vertical plane in which the rising motion occurs at higher potential temperature than the sinking motion.

Such a cell converts heat energy to potential energy and then to kinetic energy. The importance of such cells in the atmosphere, in particular the subtropical and equatorial circulation, is much discussed in theories of the general circulation. It has also been suggested that the tropical cyclone is essentially a direct cell.
See indirect cell.