When the temperature of a fluid flowing over an object differs from that of the object, heat transfer occurs. The amount of heat transfer varies depending on the fluid flow rate. Convective heat loads on TEM's are generally a result of natural convection (not artificially induced as with a fan or pump). The convective loading on a system is a function of the exposed area and the difference in temperature between this area and the surrounding gas. Convective loading is usually most significant in systems operating in a gaseous environment with small active loads or large temperature differences.