1. ATOC 4720: class 43: Final review (continue)

2. 17. Equations of motion ( )

3. 18. Scale analysis
In the free atmosphere, friction is negliginle, and thus a=0.
Observed scales:
U: 20m/s;
T: days, S
At middle latitude;

4. [1] [2]? [3]
[1]
[3]
Term [3] >> [1]; So
can be neglected;

5. 19. Geostrophic balance & effects of friction
Northern Hemisphere (NH): y L H CF
PGF
P1 P2 P3 P4 P5 x

6. Frictional convergence toward the low pressure! Important!
In PBL, friction is important.
V cross the isobars!
V cross isobars!!
Frictional convergence toward the low pressure!
Important!

7. 20. Thermally-driven circulation in the tropics: Hadley cells (ITCZ)

9. Monsoon

10. Mid-latitude baroclinic waves: thermally direct: warm air
rises, cold air sinks.
Thermal wind relation: GEOSTROPHIC WIND SHEAR
Is maintained by horizontal temperture gradients.