When air warms in one area, rises and moves horizontally as wind to another location, and then cools and descends, moving horizontally as wind back toward the original area, the pattern of circulation is called a cell.

Convection

Explanation: Convection is a method of heat transfer through the movement of fluid. Convection occurs in liquid and gases. In convection cells in a the body of fluids, liquid and gases due to differential density in the body of the fluid. The general principle in a convection cell involves fluid warming resulting in density loss and fluid is forced into a region of greater density moving horizontally as wind to that location, it then cools and descend moving horizontally back to its origin.

fertile good for trade etc