Heat energy is transmitted by the process of radiation, conduction and convection. Each of the three mechanisms of heat transfer has an important role in affecting weather changes.
Radiation:
Radiation is the process of transmission of energy from one body to another without the aid of a material medium – solid, liquid, or gas. Through the process of the transfer of heat, there is no warming of the medium.
It is by this process that most of the energy is transferred through space from the sun to the earth. The transmission takes place along straight lines. The process of transfer by radiation is similar to wave motion, and a wide range of wavelengths is possible.
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Conduction:
Conduction is the process of heat transfer through matter by molecular activity. In this process heat is transferred from one part of a body to another or between two objects touching each other.
Conduction occurs through molecular movement. Heat flows from the warmer to the cooler part of a body so that the temperatures between them are equalized.
The ability of substances to conduct heat varies in direct proportion to the heat conductivity of the substance. Thus, metals are good conductors, while air is a very poor conductor of heat.
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Besides, so long as the difference in temperature between any two bodies in contact with each other is large enough, the conduction of heat from the warmer to the cooler body proceeds at a faster rate.
As soon as this difference is reduced, the process of heat transfer is slowed down. Therefore, for the transmission of energy through this process it is essential that the difference in temperature between the touching bodies is large enough.
Convection:
Convection is the process of the transfer of heat through movement of a mass or substance from one place to another. Thus, it involves the transfer of heat by means of mass motions of the medium through which the heat is transferred.
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Convection is possible only in gases or fluids, for they alone have internal mass motions. In solid substances this type of heat transfer is impossible. In this process, the moving substances transport the heat acquired by conduction previously.