11.2 Convection in Liquids and Gases
Liquids and gases are not very efficient in conducting heat. However, heat can still be transferred through these fluids by a process called convection.
When a liquid or gas is heated, it becomes less dense (lighter) and expands. The heated liquid or gas rises above the heat source, and cooler fluid from the surrounding area moves in to take its place. This colder fluid then gets heated as well. In this way, heat is transferred through fluids by the movement of heated molecules from the hotter parts to the colder parts of the fluid.
lightbulbConvection is the transfer of heat through the actual movement of molecules from a hot area to a cold area.