从地球辐射平衡温度T e <子> < /订阅>:年代(1 - A) e (T <子> < /订阅>]= 4 e <子> < /订阅> <一口> 2 < /一口>]e S Te <一口> 4 < /一口> S是太阳常数,一个行星反照率,π圆常数(3.14159…),e R <子> < /订阅>地球的半径,e发射率,斯蒂芬玻尔兹曼常数,e T <子> < /订阅>温度我们正在寻找。求解T e <子> < /订阅>,e (T <子> < /订阅>)取消,1361.5 W和S m <一口> 2 < / >一同晚餐,0.294 e 1(总是作为1行星大气层的顶端)给出了Te = 255 K。这是低于冰点,因为水在273 K结冰,显然其他东西使表面更热——温室效应。实际表面温度Ts目前约288 K。A simple (too simple) model is the Milne-Eddington approximation: Ts = Te(1 + 0.75 τ)0.25 where tau is the atmosphere's long wave optical depth. The present value of this is about 1.84, which gives you Ts = 317 K, too high. This is because this approximation fails to account for surface cooling by convection and conduction. The more greenhouse gases you have in the atmosphere, the higher τ gets, and the higher Ts goes. Many "semigray" approximations model partial τ ("partial" meaning for each gas) as a function of the gas's partial pressure, usually raised to some power. Add up the partials to get tau. It may help to know that at present, water vapor accounts for about 50% of τ, clouds 25%, carbon dioxide 20%, and minor gases (CH4, O3, N2O, etc.) 5%. I hope this is enough to get you started.