大象传媒

Global atmospheric circulation

There are several reasons why energy is moved around the atmosphere:

  • Solar energy enters the atmosphere. Equatorial regions get the most.
  • There is more energy at the tropics than at the poles, creating an imbalance.
  • As warm air rises and cold air sinks it forms three atmospheric circulation cells north of the equator and three to the south.
  • These circulation cells move over land and sea to redistribute the energy, from the equator to the poles in both hemispheres, trying to even out the energy imbalance.

Atmospheric circulation cells

The three cell model shows how energy is moved around the atmosphere.

Hadley cell: thermally direct, clockwise from 0掳 to 30掳. Ferrel cell: thermally indirect, anticlockwise from 30掳 to 60掳. Polar cell: thermally direct, clockwise from 60掳 to 90掳.
Figure caption,
HP and LP refer to high pressure and low pressure