## Projects

1. Lapse Rate. Use the online full-spectrum radiation model at http://understanding-theforecast.org/Projects/full_spectrum.html. Adjust the lapse rate in the model and document its impact on the equilibrium temperature of the ground.

2. Skin Altitude. Answer this question using the online IR radiation model.

a. Run the model in some configuration without clouds and with present-day pCO2. Compute a T4 using the ground temperature to estimate the heat flux that you would get if there were no atmosphere. The value of a is 5.67 ■ 10—8 W/m2 K4. Is the model heat flux at the top of the atmosphere higher or lower than the heat flux you calculated at the ground?

b. Now calculate the "apparent" temperature at the top of the atmosphere by taking the heat flux from the model and computing a temperature from it using a T4. What is that temperature, and how does it compare with the temperatures at the ground and at the tropopause? Assuming a lapse rate of 6 K/km, and using the ground temperature from the model, what altitude would this be?

c. Double CO2 and repeat the calculation. How much higher is the skin altitude with doubled CO2?

d. Put CO2 back at today's value, and add cirrus clouds. Repeat the calculation again. Does the cloud or the CO2 have the greatest effect on the "skin altitude"? 