GCSE EDEXCEL B GEOGRAPHY-Hazardous earth

atmospheric circulation

1) Warm air rises at the equator = low pressure
2) cool air falls = high pressure
3) as the air falls it warms again and flows back to complete the cycle

natural causes of climate change

- The earth's orbit changes a small amount once every 100 000 years. A.K.A The Milankovitch cycle

-The amount of energy radiated from the sun changes over an 11 year cycle

-volcanic eruptions pump dust into the atmosphere causing a cooling effect

-Large asteroid Collisions can cause cooling as ash particles blocks out the sun.

-Asteroids hitting the earth can cause huge fires which release massive amounts of C02 which has a warming effect.

Possible consequences of global warming

Melting ice caps
Loss of habitat/extinction of species
Rising sea levels/flooding of coastal cities
Droughts/Loss of agriculture
Climate change/more severe weather

evidence for climate change

-arctic sea ice covers 13% less of the sea each decade

-sea levels have rises by 14cm during 20th century

characteristics of tropical cyclones

1)LOW PRESSURE: very warm, moist air rises through the atmosphere, sucking more air behind it.

2)ROTATION: the earth's spin (Coriolis force) helps the rising air to spiral and drags in strong winds (there isn't much spin at the equator)

3)STRUCTURE: tropical cyclones form a cylinder of rising, spiralling air surrounding an eye of descending, high pressure air. They are up to 640KM wide and 10KM high.

Tropical cyclones intensify when:

-water temperatures are warm-over 26.5C
-Low wind shear
-there is high humidity

Tropical cyclones dissipate when they:

-reach land because they lose energy (the are powered by water)
-move into areas of colder water
-run into other weather systems where winds are blowing in different directions

How do tropical cyclones form?

1)Warm sea temperatures (26.5^C)
2)High humidity, there needs to be a lot of moisture in the atmosphere
3)Rapid cooling- rising air must condense quickly to generate the huge amounts of energy powering a tropical cyclone.
4)Low wind shear-if winds are blowing in different directions up through the atmosphere, the cyclones won't form.
5)Coriolis force to give the cyclone spin, this isn't usually stronger

The inner core

-in the centre and is the hottest part of the Earth.
-It is solid
-made up of iron and nickel
-temperatures of up to 5,500°C

the outer core

-the layer surrounding the inner core
-It is a liquid layer
-also made up of iron and nickel

the mantle

-the thickest section of the Earth at approximately 2,900 km
-The upper part of the mantle is called the asthenosphere.
-It is made up of semi- molten rock called magma.

The crust

-the surface of the Earth.
-It is a rock layer forming the upper part of the lithosphere.

oceanic crust

-earths crust located under the ocean.
-The thinnest type of crust.
-Mostly basalt

continental crust

-found under land masses or continents.
-It is generally older than oceanic crust and is less often destroyed

'hotspot' theory

-there are fixed spots in the mantle where magma rises to the surface.
-As the crust moves over these fixed spots, volcanoes are created, eventually forming a chain of volcanoes.

Convergent (destructive) plate boundary

-usually involves an oceanic plate and a continental plate.
-The plates move towards one another and this movement can cause earthquakes.

As the plates collide, the oceanic plate is forced beneath the continental plate. ...

-This is known as subduction.
-This happens because the oceanic plate is denser (heavier) than the continental plate.

if two continental plates collide...

-neither can sink and so the land buckles upwards to form fold mountains.
-This is called a collision boundary.
-Earthquakes can occur at collision boundaries.

at a divergent plate boundary...

-the plates move apart from one another.
-When this happens the magma from the mantle rises up to make (or construct) new land in the form of a shield volcano.
-The movement of the plates over the mantle can cause earthquakes.
-aka constructive

at a conservative plate boundary...

-the plates move past each other or side by side, moving at different speeds.
-Friction occurs as plates try to move and become stuck. -Pressure builds up because the plates are still trying to move. When the pressure is released, it sends out huge amounts of energy, causing an earthquake.
-The earthquakes at a conservative plate margin can be very destructive as they occur close to the Earth's surface.
-No volcanoes

Igneous rocks

Form directly from cooling of magma or lava. Ex: granite (magma) and obsidian (lava)

Sedimentary rocks

Rocks formed from the weathering, erosion, depostion, and compaction of other rocks

metamophic rock

rock changed by heat and pressure; occurs deep underground; subductions

Sedimentary rocks can be found across ...

Sedimentary rocks can be found across lowland areas of southern and central parts of England.

Metamorphic rocks are found in....?

Metamorphic rocks are found in Northern Ireland and Scotland.

Igneous rocks can be found mainly in...?

Igneous rocks can be found mainly in upland areas in Scotland, in the Lake District in North West England and Snowdonia in North Wales and Northern Ireland.

earthquake DEVELOPED COUNTRY case study: TOHOKU 2011

when? 11 march 2011
how many deaths? 16,000 deaths
magnitude? 9
cost? 316 billion $
-shallow depth
-convergent plate boundary (oceanic plate was subducted beneath the continental plate)

earthquake DEVELOPING COUNTRY case study: Haiti 2010

when? 12 january 2010
how many deaths? 250,000 deaths
magnitude? 7
-shallow depth
-conservative plate boundary (two plates slid past eachother - friction, pressure)