September 20: The Atmosphere - Transport Medium and Reactor III, lecture material (pdf-file)

Homework for September 29:
Make sure you read all the reading assigments I gave you.
Please also refer again to the Definitions !
  1. An important means of vertical transport in the lower troposphere, the planetary boundary layer (BL), is buoyancy. Refer to Figures 4.7 and 4.8 of the reading assignment and briefly explain the terms "adiabatic lapse rate", "stable", "neutral", and "unstable condition" of the BL.  2 pts
  2. In the tropics, the Hadley Cell circulation provides for a nearly constant cloud layer near the equator, which can easily be seen from satellites. This zone is called the intertropical convergence zone (ITCZ). The seasonal position of the ITCZ is very important e.g. for tropical farming. Explain what drives the ITCZ position and what seasonal effect it has on a tropical latitude which is continuously north (or south) of the ITCZ, that means not crossed by it.  3 pts
  3. Answer Excercise 4.3 from the reading.  1 pt
  4. Complete the 'net' reaction of atmospheric methane oxidation. One formed product is formaldehyde, CH2O. Formaldehyde has a short atmospheric lifetime due to removal by photolysis and reaction with OH. Let's assume that the chemical lifetimes of these processes are 6 hours and 12 hours, respectively (which is realistic for College Station at this time of year). What is its combined chemical lifetime in the atmosphere? Assuming that methane is its only source, and that the methane atmospheric lifetime is 10 years, what would be formaldehyde's steady state mixing ratio over College Station? 2 pts
  5. The oxidation product of formaldehyde is carbon monoxide, CO, which has a lifetime in the atmosphere of 1-3 months. You learned that CH4 and CO are the principal reaction partners of the OH radical in the Troposphere. It turns out that atmospheric CO is four times as effective compared to CH4 in removing OH, i.e. the OH lifetime vs. the CO reaction is 1/4 of that vs. the CH4 reaction. What do you think would be the effects, feedbacks, and timescales of releasing a large amount of (i) methane (a greenhouse gas), and (ii) CO into the atmosphere.  4 pts
Note that I am giving 12 pts again, but will grade you on the basis of 10 pts.


September 22: The Atmosphere - Transport Medium and Reactor III, lecture material (pdf-file)