|What is convection? — DB, Corona, CA
Convection is the transfer of heat by a circulating fluid, such as air or water. This heat is carried from a hotter object to a colder object. The fluid first passes near the hotter object and receives heat. The fluid becomes warmer and more buoyant, and it's lifted upward by the colder fluid around it—just as a hot air balloon is lifted upward by the colder air around it. The rising fluid carries the heat with it. Eventually the rising fluid spreads outward and it pass near colder objects, giving up its heat. The fluid becomes cooler and less buoyant, and soon it begins to descend back toward the ground. Eventually it's drawn back past the hotter object and this cycle begins again.