Convection

In addition to heat conduction in materials through collisions of inner particles, heat can also occur through direct mass transfer. This process is called convection This phenomenon can be observed, for example, when sunlight falls through a window under which a heated radiator is located. The air heated at the radiator rises due to its lower density, while cold air flows in from below. The changing refractive index due to the density fluctuations is then noticeable by flickering in the air. This technology is used in heat sinks, which are mostly made of heat-conducting metal, to cool electronic components. The heat is transferred to the cooling fins, which in turn heat up the air. The thermal conductivity of air would be far too low to dissipate the heat. However, the heat dissipation can be greatly increased by the rising and drawing in of colder ambient air. The convection is supported by the additional attachment of fans, so that in practice even several hundred watts of waste heat can be cooled relatively easily.