Current caused by the expansion of a liquid or gas as its temperature rises. The expanded material, being less dense, rises above colder and therefore denser material. Convection currents arise in the atmosphere above warm land masses or seas, giving rise to sea breezes and land breezes respectively. In some heating systems, convection currents are used to carry hot water upward in pipes.
Convection currents in the semisolid rock of the Earth's mantle are responsible for the movement of the rigid plates making up the Earth's surface (see plate tectonics).