What is heat convection?

Heat convection is defined as a process of heat transfer that occurs through the motion of fluids, which can include liquids and gases. In convection, the warmer parts of the fluid rise due to decreased density, while cooler, denser parts sink. This movement creates a continuous circulation pattern that helps distribute heat throughout the fluid. For example, when water is heated in a pot, the hot water rises to the top while cooler water descends to the bottom, resulting in a convection current that evenly distributes heat.

This process is fundamental to understanding how heat is transferred in various natural and engineered systems, such as the heating of homes, ocean currents, and atmospheric circulation. The other options do not accurately describe convection: direct contact is relevant to conduction, the statement that convection only occurs in gases is incorrect because it also occurs in liquids, and requiring a solid medium pertains to conduction rather than convection.