Atmosphere

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Atmosphere
The energy budget
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Atmosphere
The energy budget
Explain why there is a surplus of solar energy
in tropical latitudes and a deficit towards the
poles
This graph shows that at the equator the amount
of energy received from the sun, insolation, is
much greater than at higher latitudes ie the
poles.
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Atmosphere
The energy budget
Angle of the suns rays (1)
At the equator the suns rays strike vertically,
at right angles i.e. from directly overhead .
This means that they transfer much more of their
energy to the Earth, causing more heating.
Due to the curvature of the Earth, however, at
the poles less energy from the light rays is
successfully transferred to the ground because
the angle (of incidence) is much greater.
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Atmosphere
The energy budget
Angle of the suns rays (2)
The angle at which the suns rays strike the
Earth also affect the area to be heated by those
light rays.
At the Equator isolation is concentrated on a
relatively small area, thus making the heating
there more effective.
While at the Poles the same amount of light rays
are spread over a much wider area, reducing the
effect of the heating at those higher latitudes.
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Atmosphere
The energy budget
Atmosphere to be passed through
At the Equator light from the sun passes through
a relatively narrow band of the atmosphere before
it gets to the ground. This means that most of
it will get through without being absorbed by
dust particles (dark) or reflected by clouds
(light).
At the Poles however, there is more of the
atmosphere for light to get through. This
increases the chances of it being absorbed or
reflected and thus not reaching the ground.
Y
X
The distance AB lt XY
B
A
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Atmosphere
The energy budget
Land surface and albedo effect
The land surface of the Earth at the equator is
dark equatorial rainforests. This absorbs the
light from the sun well and so heats up the
atmosphere above.
At the Poles however the land surface tends to be
lighter in colour eg Tundra or ice caps. These
are more reflective and so dont heat up as much,
meaning less heating of the atmosphere here.
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Atmosphere
The energy budget
Latitudes effect on the length of the day
The Equatorial areas of the world receive around
12 hours of sunshine all year round. Due to the
tilt of the Earths axis however the Poles find
themselves in almost total darkness for up to 3
months as they face away from the sun according
to the seasons. This dramatically reduces the
solar energy reaching the poles but maintains a
high level throughout the year for low latitudes.
At the Equator there is a steady amount of
insolation throughout the year.
At the Poles there are parts of the year with no
insolation at all.
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Atmosphere
The energy budget
Latitudes effect on the length of the day
This is the situation during winter in the
northern hemisphere (November-January). The days
are shorter, but at the Pole itself there is
complete darkness at no point in the Earths
daily rotation does the North Pole face the sun.
The equator however always faces the sun, vastly
increasing its insolation in comparison with the
pole.
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Atmosphere
The energy budget
2006
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Atmosphere
The energy budget
2005
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Atmosphere
The energy budget
2002
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Atmosphere
The energy budget
1997
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Atmosphere
The energy budget
Latitudes effect on the length of the day
The
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Atmosphere
The energy budget
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Atmosphere
The energy budget