[填空题]
The sun radiates energy to * hqr;uv; ktn+ mrpi0+9d m+sco7p* +tmtewy1 the sur; qrz:;kolji8o,6e ow)s2y ffface of the earth. Some of this energy is scattered and the rek or;:o;qi)fjw, e26y lfz8sost reaches the earth's surface.
1.Differentiate between heat transfer methods: conduction, convection and thermal radiation.
2.At any given time, the power of the radiation of the sun absorbed by the earth's surface is $P$.
$P$is given by
$P\,=\,(1−α)SπR^2$
Where $α$ is the albedo of the earth’s surface.
(1)Show that the average intensity of radiation $I_{avg}$ that is absorbed by the earth's surface is given by $I_{avg}$=$\frac{(1−α)S}{4}$.
(2)Calculate the average intensity of the radiation that is absorbed by the earth's surface. The earth's albedo is 0.3. $I_{avg}$ = $Wm^{-2}$
Some of the infrared radiation from the earth is absorbed and reradiated by the greenhouse gasses.
3.Explain this absorption and emission of radiation in terms of molecular energy levels.
