Transcript Interactive 3-cell model

• Tropical areas
receive more
insolation (energy
from the sun) than
the polar regions.
• There is an energy
surplus at the
Tropics and an
energy…
• In theory this would result in the
Tropical regions getting…and the Polar
regions getting…
• In reality, energy is transferred …
• One of the ways in which this happens is
by atmospheric circulation.
The Single Cell Model
• The single cell model was
proposed in 1735 by George
Hadley. It suggests that:
• Air at the Equator is heated up
causing it to …,creating a belt
of …
• The warm air moves towards
the poles where it…,creating a
belt of…
• Surface winds always blow…
• This completes the Hadley
Cell.
• In this way, surplus energy
from the Equator is
transferred polewards.
The Three-Cell Model
• Later observations proved that Hadley
cells exist but only extend as far as
30°N and 30°S of the Equator. This is
because the air warm air… before it
reaches the Poles.
• In reality there are actually three cells
–the Hadley cell…
The Hadley Cell
• The Hadley cell extends from the
equator to…
• Air at the equator is heated up.
• Warm air rises creating a zone of…
• Warm air moves polewards but
begins to…
• The cold air sinks at… creating a
zone of…
• The cold air then flows back
towards the equator because
surface winds always blow from…
The Polar Cell
• At the Poles, air is being cooled. Cold
air is dense and therefore…
• The descending cold air moves towards
the lower, warmer latitudes.
• As it moves towards the lower latitudes
it becomes warmer and therefore … at…
creating a zone of …
• The rising warm air then moves
polewards completing the Polar cell.
The Ferrel Cell
• The Ferrel cell lies in between the
other two cells.
• The Hadley cells and Polar cells are said
to thermally … cells because they are
driven by …
• The Ferrel cell is a thermally… cell
because it is driven by friction between
the other two cells
The Ferrel Cell
• As the air in the Hadley Cell… at
about 30ºN and 30ºS, it pulls
the air beside it… as well, due
to…
• As air in the Polar Cell… at about
60ºN and 60ºS, it pulls the air
beside it… as well.
• In this way… air is transferred
from the … cell to the … cell via
the Ferrel cell for cooling.
• And cold air is transferred from
the Polar cell to the Hadley cell
via the … for …
Global Wind Circulation
• Complete the diagram on the next slide by
filling in the blanks in the text boxes to show
the names of the pressure belts and
associated winds.
• Draw arrows on the diagram to show the wind
direction.
• Remember winds blow from high to low
pressure and winds are deflected to the right
in the northern hemisphere and to the left in
the southern hemisphere due to the Coriolis
Effect.
Polar High Pressure
Polar Easterlies
Sub-Polar…
Mid Latitude…
Sub-Tropical…
North East…
Equatorial…