Geography climate revision notes

WJEC Climate topic revision notes

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Climate revision notes
Energy in the lower atmosphere- The higher up the colder as hot air rises from the surface and cools.
The earth's surface is heated by solar radiation and this by conduction this warms the air in the
troposphere closest to the surface. The temperature decreases with altitude as the rest of the
atmosphere is heated by convection currents. The lapse rate (Getting colder the further up) happens
at 6.5 degrees per 1000 metres. Above the troposphere is another layer of the atmosphere called
the stratosphere which is where temperature starts to increase being closer to the sun. All
atmospheric systems work in the 18km thick troposphere. The energy in the atmosphere is in
equilibrium between energy entering and energy leaving. This means what goes in comes out.
The angle of incidence the sun hits the earth at means that the
same amount of solar radiation is more spread out at the poles
than it is at the equator . Therefore the energy is less
concentrated at heating the surface at the poles so the poles are
colder. This means there is an energy surplus at the equator and
energy deficit at the poles, all atmospheric circulation is the
energy being redistributed from the equator to the poles. The
Hadley energy cell which ranges from the tropic of cancer in the
north to the tropic of Capricorn in the south is one of the cells
that redistributes this heat by convection. At the equator in the
centre the surface is hottest so the hot air rises here causing low
pressure. This air cools as it gets higher causing condensation and (cumulonimbus) clouds to form.
The rain from these clouds causes the rain forests. The cool
air having risen then moves towards the tropics and falls anti
cyclonically at high pressure to make the arid deserts in this
area. The Hadley cell is also called the intertropical
convergence zone (ITCZ) and moves throughout the year
due to the changing rotation of the earth between the
summer and winter solstices leading to the wet and dry
seasons in the equatorial regions which correspond to when
the high pressure part is over head for dry and low pressure
for wet.
Rainforests are an example of biomes, a biome is simply the
main type of vegetation in an area often caused by climate.
At the last ice age (18,000 years before present) all the
biomes were in different places to their locations today. Ice
shelves covered much of northern Europe, the Australian
desert was much smaller and the Brazilian rainforest was
grassland savannah instead. Today the north of Europe is
temperate forest and the African deserts are much larger.
These correspond with the other two cells of atmospheric
circulation; the Ferrell and the polar. The Ferrell cell shares
the low pressure with the Hadley but warm air is heated
along the surface as it moves south from the equator and
meets cold polar air before rising at low pressure causing rain that causes the European forests in the

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This high pressure air cools and goes south to cool into the polar cell causing high pressure and
meets the Hadley cell to fall again at high pressure back toward the tropics.…read more

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Short term- Tambora 1815- largest eruption in recent times and 1816 was the year without a
summer.
Short term- Mount St Helens 1980- Dust in Atmosphere caused an increase in rain levels
Medium term- Potential that the little ice age was caused by volcanism as volcanic activity
was increased in this period
Medium term- Potential the Medieval warm period was caused by a lack of volcanism as
volcanic activity was decreased in this period
Long term- Super volcanoes can cause long term climate affects.…read more

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The problem is made worse by the reduction of carbon sinks,
these are long term carbon stores like forests, fossil fuels and the oceans.
An effect of climate change is sea level rise, the deglaciation of Greenland would cause Eustatic sea
level rises (Across the whole world) which would displace over 100 million in China and India alone.
Any melt of ice caps caused by global warming would increase sea levels.…read more

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There are several ways climate change has been combated. These include international negotiations
at each summits such as Rio in 1992 and Kyoto in 1997. These negotiations are difficult due to
different interests of countries (e.g. China grow industrially and the Maldives to reduce sea level
rise.). This has led to negotiations being dominated by groups such as the LDC one of 48 poor
countries.…read more

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