1. ATOC 4720 class 41 Tropical thermally direct circulation: Hurricanes;
Tropical thermally indirect circulation: the deserts;
3. Middle-latitude thermally direct circulation: baroclinic waves.

2. Previous classes:Thermally-direct circulation: f=0
CONCEPT:
Top of atmosphere
Pole EQ
Surface
Available Potential E --> Kinetic E

3. Potential E converted to Kinetic E
POLE EQ

4. Thermally-direct: Symmetric Hadley Cells (f=0)
High P
Pressure
High P
High P
Low P

5. OBSERVATIONS:
WINTER EQ

6. Thermally-direct: monsoon
SUMMER

7. 1. Thermally-direct circulation in the tropics: Hurrianes

8. Thermally-direct Warm core [1] Thermally-direct: warmer air rises,
colder air sinks;
[2] Potential energy
convert to Kinetic
energy:
generation and
maintainance of
warm core: low-level
moist air inflow+sensible
heat (air/sea interaction),
and CISK.

9. Thermally-indirect circulation in the tropics: the deserts
Desert feature: extremely hot and dry air--a result of large-scale subsidence;
Sinking air is warmer than surroundings: thermally indirect.

10. The deserts NOT driven by heating contrast;
It is driven by a continual input of kinetic
energy from other regions of the tropics;
Why sinking in these regions? Not intuative.
Numerical models: well simulated;
Suggested: semiarid regions large changes in
the earth’s surface characteristics may be
Important. Erosion due to extensive grazing: albedo:
reduce turbulent heat fluxes--reduce upward motion;
Favor subsidence.

12. 3. Middle latitude baroclinic disturbances: thermally direct
Lab experiment:
Cold
HOT

13. Assume500mb