1. ATOC 4720 class37 1. The vertically averaged divergence
The primitive equations
The general circulation: description
Thermally driven circulation in the absence of rotation

2. 1. Vertically averaged divergence
Atmosphere: high degree of compensation:
One level digergence -- the other level convergence.

3. Structure of external and internal waves
There is vertically averaged divergence
Complete Compensation
Of divergence
Internal
External:

4. 2. Primitive equations: ( )

5. 3. General circulation: description
Ultimate energy source: solar radiation

7. General circulation Two broad classes atmospheric motions:
Driven by horizontal heating gradients in
stably stratified atmosphere
(98% kinetic Energy);
large-scale: synoptic-planetary (gestrophy);
sometimes convert to small-scale: instabilities
(2) Driven by convective instability (2%);
important for transport latent and sensible heat
from earth’s surface upward;

8. General circualtion: description
Usually, general circulation--indicates motion
as type (1): Large scale
Energy cycle: Large-scale horizontal heating
gradients -- potential energy -- convert to Kinetic
energy -- dissipation;
General circulation is maintained by the
horizontal heating gradients. (say Hadley cell)

9. Dynamical point of view: hotizontal heating
gradients -- horizontal pressure gradients --
large-scale horizontal motion;
Geostrophic adjustment process: PGF, Coriolis Force;
In lower latitudes: most kinetic energy is
quasi-steady, thermally driven
circulation -- caused by
uneven distribution of heat
sources and sinks;
Monsoon and ITCZ
Mid-latitude: daily change is large: baroclinic waves
Frictional dissipation in PBL

10. 4. Thermally driven circulation without rotation

12. Convergence
Divergence
Z-coordinate: If