From Simple English Wikipedia, the free encyclopedia
Water naturally moving in a pot showing convection currents
Convection is the movement ofheat because of the movement of warmmatter. Convection is defined as the method of heat transfer through a fluid from places of higher temperature to lower temperature by the movement of the molecules due to their different densities.
For example,atmospheric circulation moves warmair to cool places, causingwind. Wind, in turn, can enter and cool a room if the window is open. The movement of theclouds, theocean currents and many types ofheaters are examples of convection.
Convection can happen naturally ("natural convection") or because of a moving device ("forced convection").
Thefan is a device that moves air artificially. The air in this case is moving because of the rotation of the fan. This is an example of "forced convection".
Natural convection happens because a fluid is lighter when hot and heavier when cold. Thus, if a fluid has a hot part and a cold part, the hot part naturally moves upward and the cold part naturally moves downward. For example, if the water in a pot is hotter near the bottom because of the fire, it rises from the bottom to the surface. At the same time the water near the surface is colder so it sinks to the bottom.
Convectioncurrents occur when there are significant differences intemperature between two parts of afluid.[1] When this happens, hot fluids rise and cold fluids sink.[1] This causes movements or currents in the fluid.[1]Atmospheric circulation, for example, is made by convection currents.
