Topic 1 : Hazardous Earth Flashcards
Name the parts of the Earth
Crust
Mantle
Outer core
Inner core
Name the two parts of the upper mantle
Lithosphere and asthenosphere
What is the outer core made of?
Iron and nickel
Name the plate boundaries
Divergent
Convergent
Conservative
Collision
What happens in divergent plate boundaries?
Plates move apart
What happens in convergent plate boundaries?
Plate moves under the other
What happens in a conservative boundary?
Plates slide past each other
What happens in a collision boundary?
Plates move towards each other
What are tectonic plates?
The earth’s surface broken into large pieces
What is radioactive decay?
Atoms of radioactive elements release particles from nuclei and give off heat
Describe oceanic crust
Very thin
Made of basalt
Thin but more dense
Describe continental crust
Low density
Made of thick granite
Thick but less dense
How do earthquakes happen?
Tectonic plates move
This is concentrated along fractures
Friction builds up against plate boundary until energy is released
This energy is sent out as seismic waves
What is the epicentre?
The point on the Earth’s surface above the focus
What are seismic waves?
Earth’s energy being released
What is the focus?
Point inside the crust where pressure is released
What are hotspot volcanoes?
Warm areas in the mantle where heat moves up and forms in the middle of a plate
What causes a tsunami?
Destructive/convergent wave plate movement causes earthquake
Sea above is forced upwards
This movement causes tsunami
Seismic waves spread and waves crash onto shore
What is climate?
Average weather over 30 years
What are ocean currents?
a continuous, directed movement of sea water generated by a number of forces acting upon the wate
What is a Hadley cell?
The largest cell
Warns air rises out the equator and travels around 30 degrees north where it cools and sinks
What is a Ferrel cell?
Smaller cell
Found between Hadley and Polar
Powered by other two cells
What is a Polar cell?
Smallest cell
Cold air sinks at North Pole and warms
What are differences in climate caused by?
Gulf Stream
How can we learn about past climate?
Historical sources
Ice cores
Tree rings
What is the Greenhouse effect?
Warming of Earth’s surface and the air above it. It is caused by gases in the air that trap energy from the Sun
Describe the pressure over land
Land heats the air above which expands and becomes tighter and rises
Forms are of low pressure in the summer
and in the winter high pressure
Describe the pressure over sea
Sea takes longer to heat and cool, the air above dense
High pressure in the summer
Low pressure in winter
Describe pressure over wind
Created when air moves from high to low pressure
Describe the process of ocean current formation
Cold, salty water sinks Creates a convection current Drags water down Warmer water is drawn from the equator Cool air sinks It flows south to the equator and is warmed again
Why is heat distributed around the Earth?
Because it’s to pressure difference and ocean currents
What is ITCZ?
Inter-TropicL Convergence zone
Describe characteristics of the ITCZ
Part of global circulation model Forms within the tropics Forms when 2 air masses meet Created within the Hadley cell Area of low pressure and stretches around the Earth and brings rain
Describe characteristics of a Hadley cell
Caused by heating + cooling
Creates low and high pressure
Consists of 2 parts - 1 on either side of the equator
Both parts move together as the Sun moves overhead seasonally
Name the 5 main stages of ITCZ
Land warms air - expands becomes lighter + rises
Cooler high pressure air forms as the sea is cooler than the land
Trade Winds blow from high to low pressure towards the Southern Sahara
High pressure forms over Atlantic Ocean because sea is cooler than land in northern hemisphere summer
Trade Winds blow south, drawn by low pressure at ITCZ
Water vapour condenses to make rain
Describe the crust of the Earth
50km thick
5 - 70 km thick
Solid rock
Describe the Earth’s mantle
2900km thick
Upper mantle - lithosphere + asthenosphere
Lithosphere - close to crust, more liquid
Asthenosphere - underneath lithosphere, less liquid
Lower mantle - reaches to outer core
Describe the Earth’s outer core
2266 km
4000 - 5700 degrees Celsius
Made of iron and nickel
Describe the Earth’s inner core
Solid - iron and nickel
Same temperature as surface of the sun
The moving of the Earth’s crustal plates are due to what?
Convection currents
Where do convection currents occur?
In the mantle
Explain why the Earth’s crust is unstable
Due to the mantle - the upper mantle has a lithosphere which is more liquid and closer to the crust and also has an asthenosphere which has some liquid underneath, making the crust unstable so when liquid is heated it causes movement
Due to convection currents - created by heat from within the Earth and are the cause of the movement of the Earth’s crustal plates
Why do not all volcanoes form at plate boundaries?
Because there are cracks in tectonic plates
The magma and the mantle then rises to form a volcano
How do earthquakes happen?
Movement of Earth’s tectonic plate
Concentrated along fault lines (fractures in Earth’s crust’
Friction builds up along plate boundaries as they move against each until energy is released
This energy is sent out as seismic waves
How is a tsunami formed?
Destructive/ convergent plate movement causes earthquake
Sea above earthquake is forced upwards
Sea movement causes a tsunami
Seismic waves spread quickly
Waves crash onto shore devastating low lying area
Explain differences between shield and composite volcanoes
Plate boundaries - shield is found on divergent plate boundary
Composite is found on convergent plate boundary
Lava - composite has layered lava which is very sticky
Shield has runny lava
Explain how ocean currents can influence climates
By moving cold and warm water around the globe. Currents carry warm water from the tropics towards the poles and bring water back toward the equator which makes the ocean cooler
OR
By affecting temperature. The constant cycling of water helps moderate temperatures across the planet, by creating ocean temperature variations that less extreme than those found on land
What is low pressure?
Warm air rises in areas of low pressure
As it rises and cools, water vapour condense to form clouds precipitation
What is high pressure?
As air is heated at the equator, it rises and begins to descend at around 30 degrees latitude and the air is cooled
Does air rise or sink in low pressure?
Rise
Does air rise or sink in high pressure?
Sinks
What is the ITCZ?
Zone of convergence at the thermal equator where the trade winds meet
It is a low pressure belt and migrates with the changing position of the thermal equator
Explain why some areas in Africa are desert and some are tropical rainforest
Pressure belts - a low pressure belt between 0 and 30 degrees causes rainfall which is why some areas are tropical rainforest
High pressure belts bring dry climates due to the air sinking which why some areas are desert
What is climate?
Average weather over 30 years
What is the greenhouse gas effect?
The way that gases in the atmosphere trap heat from the sun
The gases let heat in but prevent most of it from getting out
Describe the greenhouse effect process
Short wave radiation passes through the atmosphere
Some short wave radiation is absorbed and converted into Long wave radiation
Some long wave radiation passes back into space
Some long wave radiation is reflected off greenhouse gases back to Earth and heating Earth
Explain one difference between the oceanic and continental crust
Oceanic crust has a higher density compared to continental which has a lower density
Continental crust is 30-50 km thick and oceanic is 6-8 km thick
Explain why earthquakes happen on collision plate margins
Plate boundaries move towards each other
The collision plate margins move towards each other and this movement of colliding causes the friction to build up against each other which releases energy out into seismic waves
What is a destructive plate margin?
When two tectonic plates move towards one another. The oceanic crust is forced to sink back into the mantle, whilst the continental crust rises above. Volcanoes and earthquakes are found here
Where was Haiti Earthquake located?
Haiti
Between Caribbean and North American plates
Occurred on a destructive plate margin
25 km away from capital - Port au Prince
State 5 key facts about Haiti earthquake
Magnitude - 7 Occurred on 12th January 2010 - 4:53pm Conservative plate boundary Epicentre was 25km from Port au Prince 250,000 people died
State primary effects of Haiti earthquake
Roads blocked
No telephone system - no internet or mobile phone signal
Key government buildings destroyed
Hospitals destroyed
State secondary effects of Haiti earthquake
Cholera outbreak due to poor sanitation
3,000 temporary tent schools set up
Mass graves dug
1.5 million people sleeping in shelters
State immediate responses from Haiti earthquake
Health care supplies provided to limit disease
National government began coordinating humanitarian aid
State long - term responses from Haiti earthquake
Water and sanitation eventually supplied for 1.7 million people
$100 million in aid by US
$330 million by European Union
Explain one way in which the global atmospheric circulation determines the location of high rainfall (low pressure) areas
The ITCZ/equator is a low pressure area with high rainfall - here warm air rises + cools as clouds are created
A further area of low pressure found at around 60 degrees north and south of equator
Warmer air rises as it meets colder air + water vapour condenses
At equator less dense air rises, cools and condenses giving rain
Why 3 things causes places near the Equator to be much warmer than places near the Poles?
This is due to a combination of:
the curvature of the Earth
angle of the sun in the sky
layer of atmosphere surrounding Earth - contains smoke particles that absorb heat
Why are places near the Equator much warmer?
At the equator the sun is at a high angle and shines vertically downwards
Heat is concentrated in a small area, resulting in it rapidly becoming hot
Solar radiation passes through atmosphere at a direct angle so less heat is lost
