T/G Layout 1

reaches the cold polar regions
and then sinks. This would be a
direct way to restore the system
to balance. However, due to
complex effects, the circulation
associated with the differential
heating of the atmosphere is not
a simple one-cell circulation from
equator to pole. Instead, a more
complex multi-cell structure acts
to transport heat energy from the
equator to the poles.
figure 7.

figure 8a. Simplified View of General Circulation

How is energy transported poleward?

Simplified View of General Circulation

The rising air near the ITCZ diverges at the top of the troposphere and some portion travels north.

As the air moves north it radiates energy into space and cools. As it cools it becomes more dense and sinks

. The area of sinking motion, or subsidence, occurs near 30°N. A region with strong subsidence is typically
very clear and warm with light winds. The subsiding air reaches the surface and branches outward with
the northern branch traveling north and the southern branch traveling south to complete Hadley cell
circulation. The northern branch collides with cold, dense polar air moving south. This area, marked
by the cold front symbol ( ) is often the location of frontal zones and cyclonic disturbances.

5

4

1

3

2

6

7

North Pole

Equator

Earth

30 °

60 °

Hadley

Cell

Ferrel

Cell

tropopause

troposphere

northe ast tr ade winds

prevailing westerlies^6

4

7

5

1

2

3