Geography Reference
In-Depth Information
over a large area near the poles compared to the equatorial regions
where it is more concentrated. This creates a north-south tempera-
ture gradient and as heat is always transferred from hot materials to
cooler materials then the warm air (and oceanic water) from the
equator will naturally try to rise and move polewards at high alti-
tudes within the troposphere to be replaced by lower level winds/
ocean currents moving in the opposite direction.
The second driver of global wind circulation is the Earth's rota-
tion. If the Earth did not rotate and only one side faced the Sun
then surface winds would blow from the cold dark side to the hot
daylight side as rising air over the hot side would need to be
replaced by colder air drawn in. However, the Earth's rotation acts
to create an apparent deflection of winds to the right in the north-
ern hemisphere and to the left in the southern hemisphere which is
a process known as the
Coriolis effect
and which is stronger as
you move toward the poles.
The other effect of the Earth's rotation relates to the tilt of this
rotation and its impact on the seasons. The rotation of the Earth is
not perpendicular to its rotation around the Sun and is tilted to
23.5° as shown in Figure 1.1. This drives seasonal cycles upon
Figure 1.1
Diagram showing how the Sun's energy is more concen-
trated near the equator and more diffuse at the poles.
