Heat transport via atmosphere

How much thermal energy is transferred through air? It depends on the thickness of the gap I believe and the temperature difference.

 

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It also depends on the cross-sectional area of the gap. If the thickness is \(d\), the cross-sectional area is \(A\), the temperature difference is \(\theta\) and the thermal conductivity of air is \(k\), the amount of heat \(q\) transferred in time \(t\) is given by

\(q\ =\ \frac{kA\theta t}d\)​

The thermal conductivity of air between 0°C and 27°C is about \(0.025\ \mathrm{W\,m^{-1}\,K^{-1}}\) according to the Wikipedia list of thermal conductivities. So rate of heat transfer through an air gap of thickness 1 metre, cross-sectional area 1 square metre and temperature difference 1°C in is about 25 millijoules per second.

 

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I have seen the formula before, but I do not know if it is very accurate.. there are probably variables that would change the outcome- such as air flow and confinement of gas molecules. I suppose it can't be too far off from the truth.

 

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Actually, conduction is an extremely bad way of transferring heat through air. Heat is much more usually transferred through air by convection instead – in which case, I would say that the process is likely to depend more on such factors as density and thermal absorptivity and less on the dimensions of the pocket of air through which transference takes place.

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