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Atmospheric Circulation
Ferrel Cells
The Ferrel Cell is the average motion of air in the mid-latitudes. It is
characterized by sinking air near 30 deg and rising air farther poleward. At
the surface, air flowing poleward is deflected to the east by the
coriolis force, resulting in
westerly surface winds.
The Ferrel Cell can be difficult to understand because it has rising air where it is relatively cold, and sinking air where it is relatively warm. Why is this? First we must understand the concept of "eddies."
What is an eddy?
Eddy is another word for wave. If you are standing in the calm ocean, the sea level around you is pretty constant. However, as soon as a wave comes by the sea level changes from its normal level, first decreasing and then increasing.
In the same way, eddies are changes in the normal, or average, conditions in the atmosphere. They occur in regions of strong temperature gradient (where the temperature goes from warm to cold over a short distance). Eddies act to warm the cold area and to cool the warm area by mixing the air. They are associated with midlatitude cyclones, which typically have both cold and warm fronts.
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Links and resources
Ferrel Cells
The Ferrel Cell is the average motion of air in the mid-latitudes. It is
characterized by sinking air near 30 deg and rising air farther poleward. At
the surface, air flowing poleward is deflected to the east by the
coriolis force, resulting in
westerly surface winds.The Ferrel Cell can be difficult to understand because it has rising air where it is relatively cold, and sinking air where it is relatively warm. Why is this? First we must understand the concept of "eddies."
What is an eddy?
Eddy is another word for wave. If you are standing in the calm ocean, the sea level around you is pretty constant. However, as soon as a wave comes by the sea level changes from its normal level, first decreasing and then increasing.
In the same way, eddies are changes in the normal, or average, conditions in the atmosphere. They occur in regions of strong temperature gradient (where the temperature goes from warm to cold over a short distance). Eddies act to warm the cold area and to cool the warm area by mixing the air. They are associated with midlatitude cyclones, which typically have both cold and warm fronts.
Next page -> Ferrel Cell continued
Links and resources
