convectional, adj.
/keuhn vek"sheuhn/, n.
1. Physics. the transfer of heat by the circulation or movement of the heated parts of a liquid or gas.
2. Meteorol. the vertical transport of atmospheric properties, esp. upward (distinguished from advection).
3. the act of conveying or transmitting.
[1615-25; < LL convection- (s. of convectio) a bringing together. See CONVECT, -ION]

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Process by which heat is transferred by movement of a heated fluid such as air or water.

Most fluids expand when heated. They become less dense and more buoyant, and so rise. The heated molecules eventually cool, become more dense, and sink. This repeated process sets up convection currents that account for the uniform heating of the air in a room or water in a kettle. Air convection can be forced by a fan, and water convection by a pump. Atmospheric convection currents can be set up by local heating effects such as solar radiation or contact with cold surfaces. Such currents are usually vertical and account for atmospheric phenomena such as clouds and thunderstorms.

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      process by which heat is transferred by movement of a heated fluid such as air or water.

      Natural convection results from the tendency of most fluids to expand when heated—i.e., to become less dense and to rise as a result of the increased buoyancy. Circulation caused by this effect accounts for the uniform heating of water in a kettle or air in a heated room: the heated molecules expand the space they move in through increased speed against one another, rise, and then cool and come closer together again, with increase in density and a resultant sinking.

      Forced convection involves the transport of fluid by methods other than that resulting from variation of density with temperature. Movement of air by a fan or of water by a pump are examples of forced convection.

      Atmospheric convection currents can be set up by local heating effects such as solar radiation (heating and rising) or contact with cold surface masses (cooling and sinking). Such convection currents primarily move vertically and account for many atmospheric phenomena, such as clouds and thunderstorms.

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Universalium. 2010.

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