There are three primary mechanisms of heat transfer: conduction, convection, and radiation. All three methods involve the transfer of energy from a warmer object to a cooler one.
-Conduction is the direct transfer of heat between two objects that are in physical contact with each other. The molecules in the warmer object vibrate more rapidly than those in the cooler object, and these vibrations are transferred directly to the cooler object. Metals are particularly good conductors of heat, which is why metal pans are often used for cooking.
-Convection is the transfer of heat via fluid motion. When a fluid (liquid or gas) is heated, it becomes less dense and rises. This movement creates convection currents that circulate warm fluids away from the heat source and colder fluids back towards it. Convection can be natural, like when warm air rises and cold air sinks in Earth’s atmosphere, or it can be manmade, like when water is heated in a radiator.
-Radiation is the transfer of heat via electromagnetic waves. All objects emit radiation (even our bodies!) but some objects emit more than others. The hotter an object is, the more radiation it emits. Radiation can travel through empty space–that’s how we get sunlight on Earth!–but it can also be absorbed or reflected by other materials.