Assignment #9: Due on Wed, March 23. 1. Use the simple model of the greenhouse-gas effect of the Earth given in Lecture note §18.1.7 to address the following two issues. (a) Discuss the effect of increasing atmospheric CO 2 concentrations from the current value of ~388 ppm on the future Earth surface temperature, if the CO 2 level is so high that the transmittance ρ t of the outgoing thermal radiation in the infrared (IR) region of 13-17 μ m at the atmosphere becomes zero . (b) On the basis of the greenhouse effect per molecule, the effect of CFCs (freons) is 10 4 times that of CO 2 . But the atmospheric concentrations of CFCs are ~500 ppt, which are ~10-6 times that of CO 2 . Note the CFCs have strong absorption bands in the IR range of 8-12 μ m, which exactly lies in the atmosphere “window”. Thus the saturation of the atmospheric absorption by CO 2 in 13-17 μ m, if occurs, will not affect the greenhouse effects of CFCs.
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