Meteo 431  Atmospheric Thermodynamics  Spring 2002

Problem set # 3

assigned:    25 January 2002

due:            1 February 2002

1.  What are the mean molecular speeds of hydrogen, water vapor, nitrogen, and lead? How do these compare to the mean molecular speed of dry air? 

2. Calculate the following quantities of the Martian atmosphere:

a. mean molecular mass;

b. surface density (kg m^-3);

c. mean molecular speed;

d. mean atmospheric scale height.

(You can easily find the composition, pressure, and temperature of the Martian atmosphere, and Mars’ gravitational acceleration on the web.)

3. Consider the air in the weather station. Assume that the pressure changes by 5 hPa and the temperature changes by 5 K. Assume that the weather station is sealed.

a. What is the change in the atmospheric density?

b. Which has a greater effect of the pressure – the change in pressure or the change in temperature?

4. Assume that vertical atmospheric winds suddenly cease, that the atmosphere is not well mixed by eddies, and that the molecules are allowed to diffuse until their vertical distributions are given by their individual scale heights. What would be the new mole fraction of molecular oxygen at the surface? Would we be able to breathe? (hint: Assume that no molecules escape from Earth’s atmosphere in this process.)

5.  B&A, # 28.

6. B&A, # 30.

7. B&A, # 33.