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While atmospheric pressure decreases rapidly with increasing altitude, changes in
temperature are more complex and is divided into 4 main layers:
The zone closest to the Earth and where most weathering takes place.
Exhibits the highest temperatures as radiation from the sun warms the Earth's
surface which then warms the air directly above it by the process of
convection, conduction and radiation.
However, this affect decreases rapidly with distance away from the surface as
air temperature drops by 6.…read more

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Temperature decreases rapidly (similarly to in the troposphere) but this time
to much cooler temperatures of 90°C.
Here there is no water vapour or dust to absorb radiation.
Very strong winds of 3,000 kmph.
Culminates in another isothermal layer called the mesopause.
So named due to the increase in temperature resulting from the absorption of
UV radiation of atomic oxygen found at this altitude.…read more

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This results in major heat transfers:
Horizontal. 80% of heat transferred away from the tropics is carried by winds
in the jet stream (an intense thermal wind in the upper troposphere),
hurricanes and depressions. The remaining 20% is transferred by the
movement of warmer ocean currents towards the poles.
Vertical. Energy is transferred from the warmer surface of the Earth to the
colder atmosphere by radiation, conduction and convection. Latent heat
(additional energy needed to change the state of a substance) helps transfers.…read more

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As the temperature of an air mass is determined by the area over which it
originated and the surfaces over which it has passed, winds blowing in from
the sea tend to be cooler in summer and warmer in winter than winds that
have travelled over land.
Surface ocean currents are caused by prevailing winds blowing over the sea.…read more

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The General Atmospheric Circulation
Winds are caused by differences in air pressure with air moving from areas of high
pressure to areas of low pressure.
Variations in air pressure occur because of changes in temperature and altitude.
Air pressure decreases with increasing height from the surface of the Earth.
When air temperature increases it becomes warmer, less dense and will rise,
creating an area of low pressure underneath.…read more

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This frictional force is less pronounced than over the surfaces of the smoother
At higher altitudes, frictional forces are reduced and the effect of the pressure
gradient dominates with winds travelling from high to low pressure across the
The TriCellular Model
Differences between the amount of solar radiation at the equator and at Polar
Regions indicates a simple movement of air towards the poles from warm tropic
However, the rotation of the Earth complicates this.…read more

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The remaining air travels towards the poles.
These winds pick up moisture when they cross the ocean and are responsible for
bring a lot of wet weather.
When these winds meet the colder air of the Arctic at the polar front they rise up to
form the boundary between the Ferrel and Polar cells.
This area of warmer, unstable air is associated with depressions and heavy rain.
The position of the ITCZ changes according to the seasons.…read more

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Relief rainfall occurs when moist air that has been travelling over the sea is
forced to rise over upland areas.
As it rises and cools, the air reaches dew point (the point where air becomes
saturated) and then condenses which leads to rainfall.
Warmer air can hold more moisture.
The UK is particularly affected by frontal rainfall.
This is where a band of warm air is pushed up over a wedge of cold air where
two air masses meet in a frontal system.…read more


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