Geography
Instructions: Problem sets are by the time and date given. Please submit all answers digitally via Canvas. Make sure
you write clearly and show all your work. Please list anyone else you worked with on each assignment
1. (30 pts total) Suppose we move a parcel of air at a temperature of 25°C, and with a dew point
temperature of 15°C up and back down a mountain 4 km in height. Assume the normal wet and dry
adiabatic lapse rates apply. On the diagram below show the following. Assume a SALR = 5 C/km, and an
ELR=7 C/km. Estimate the specific humidity (SH) using the plot from PS 2.
a) the elevation at which clouds will occur (the lifting condensation level); b) the temperature of the parcel at the
top of the mountain; c) the temperature the parcel will have when it descends to the bottom on the
far side of the mountain; d) the portions of its journey where it follows the wet and dry rates e)
explain why the parcel is warmer/cooler/same temperature on the back side of the mountain as compared
to when it started.
Problem Set 3 Handed Out: 26 Feb (Sunday) Due: 9 Mar by noon (Thursday)
GEOG 301 Advanced Environmental Systems Spring 2017 (R. Dubayah & G. Hurtt)
f) Fill out the table above. Assume the SH falls as the temperature falls once saturation is reached (don’t
worry about changes in pressure) (table counts for 10/30 pts)
g) Draw the temperature of the parcel and the temperature of the environment on the plot below (i.e. draw
the segments where the parcel follows the DALR and SALR on its journey up and down. Does the parcel ever
reach a level of free convection (where it would rise by itself because its warmer than the surrounding air)?
(10/30 pts)
ELEV [km] T [C] TDEW [C] SH [g/kg] RH [%] TENV [C] 0 25 15 25 1
2 3 4
0
2. Find the maximum angle of the Sun above the horizon on your birthday. a) List your birthday b) What is the
declination of the Sun on that day at noon? c) What is the zenith angle of the Sun, and the angle
above the horizon?
3. Use a diagram to describe Hadley cells. Why does the Hadley circulation change seasonally?
4. Explain how the geostrophic wind forms using a diagram. What forces are in play? Why is there no
geostrophic wind at the surface?
5. Calculate the velocity of the geostrophic wind that would occur between points (A) and (B) on the map
below. Assume: The pressure at (A) = 540 mb and at (B) = 532 mb, the distance between (A)
and (B) is 400 km, the latitude is 35°, and the density of air is r = 0.70 kg/m3. Make
sure all units are expressed in the SI units of kg-m-s (i.e. remember to convert km to m, and
mb to Pa). Draw the direction the wind would be moving on the map as well.
6. (20 pts) Draw a diagram and explain the atmospheric and oceanic circulations that occur in the tropical
Pacific during an ENSO event.
7. What is the Ekmann Spiral? Why does it occur?
