Convection

Convection is the transfer of heat through the physical movement of a fluid, in which warmer, less dense material rises while cooler, denser material sinks. It arises spontaneously from density differences, typically caused by temperature variation, combined with gravity and buoyancy, and requires gravity to occur; it does not happen in microgravity such as aboard an orbiting spacecraft. The resulting circulating flow carries heat by bulk movement of the fluid itself rather than by direct molecular contact between particles. On Earth, convection drives major natural systems: atmospheric circulation and weather patterns, ocean currents, and the slow motion of the planet's rocky mantle. The same mechanism also powers energy transport inside stars, including the Sun. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/