Thursday, September 4, 2008

Transfer of Thermal Energy


Convection is the name for a means of heat transfer, as distinguished from conduction and radiation. It is also a term that describes processes affecting the atmosphere, waters, and solid earth. In the atmosphere, hot air rises on convection currents, circulating and creating clouds and winds. Likewise, convection in the hydrosphere circulates water, keeping the temperature gradients of the oceans stable. The term convection generally refers to the movement of fluids, meaning liquids and gases, but in the earth sciences, convection also can be used to describe processes that occur in the solid earth. This geologic convection, as it is known, drives the plate movement that is one of the key aspects of plate tectonics.
Conduction is the transfer of energy through a medium such as heat or electricity through metal, without any apparent change in the medium.
Radiation is energy radiated or transmitted as rays, waves, in the form of particles. Higher doses of radiation may be used to kill cancerous cells.

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