ETYM Latin convectio, from convehere to bring together; con- + vehere to carry.
1. The transfer of heat through a fluid (liquid or gas) caused by molecular motion.
2. (Meteorology) The vertical movement of heat or other properties by massive motion within the atmosphere.
Transmission of energy or mass in a medium by movement of the medium itself.
Conveying; movement of particles of fluid due to alterations in density, especially caused by heat.
Heat energy transfer that involves the movement of a fluid (gas or liquid). According to kinetic theory, molecules of fluid in contact with the source of heat expand and tend to rise within the bulk of the fluid. Less energetic, cooler molecules sink to take their place, setting up convection currents. This is the principle of natural convection in many domestic hot-water systems and space heaters.