Convection is the transfer of heat within a fluid (a gas or a liquid) by means of motion of the fluid (fluids are very poor conductors). In natural convection, currents of warm and cold fluid arise by virtue of the warmer parts being less dense than the cooler parts. Thus the warmer fluid rises and the colder fluid sinks under the influence of gravity. In forced
convection, some external cause, such as a fan, drives colder fluid into a warmer one, or vice versa. Research Convection