Edexcel B GCSE Geography - Paper 1 Topic 1 - Hazardous Earth

Define andesitic lava

a thick and sticky lava erupted from composite volcanoes

Define asthenosphere

the upper layer of the earth's mantle, below the lithosphere, in which convection currents cause tectonic plate movements.

Define basaltic lava/rock

lava/rock that is low in silica, fluid and flows easily

Define base isolators

flexible pads on which a building is built to help it withstand earthquakes by isolating it from the moving ground

Define cirrus

a type of cloud that appears as thin wisp-like formations at high altitudes

Define climate

Is the average weather at a given place over a long period of time.

Define climate graph

A graph showing the average temperature and rainfall at a particular place

Define conservative plate boundary

when two plates are sliding alongside each other

What biome is found at the equator, and why?

tropical

This is because the equator recieves the most direct sunlight, so its energy is more concentrated here

What biome is found at the tropics of cancer and capricorn?

desert

What biome is found at the poles?

Polar/ tundra

Why is it colder at the poles?

The sun's energy is spread over a greater area, so it is less concentrated

Is the Tropic of Cancer north or south of the equator?

north

What degree is the tropic of cancer found?

23N

What degree is the tropic of capricorn found?

23S

What are the three air cells found around the earth?

polar, ferrel, hadley

What degrees are the hadley cells found at?

0 - 30N/S

What degrees are the ferrel cells found at?

30-60 N/S

Describe air circulartion in the Hadley cells?

• the air above the equator heats up from the sun's radiation, it rises, which leads to low pressure and rainfall

• This air rises around 18km until it reaches the troposphere. It then moves North (or South). The air becomes colder and denser, so falls creating high pressure and dry conditions before moving back towards the equator.

Describe air circulation in the polar cells?

Cold air falls at the North (or South) Pole and then moves back south (or north) at the surface of the earth to 60 degrees N/S. Here, it is warmed by contact with land/ ocean so it rises again.

What are the cases of global heat diffrenciation?

ocean currents, air circulation, the curvature of the earth

Describe how surface currents are caused? What are they?

They are found in the top 10% layer of the ocean, and are caused by wind

The wind is caused by the global air circulation cells, so here it can be said that the cells are more important as they cause the surface currents.

How are deeper currents caused?

• They are caused by changes in water density

• In the Arctic and Antarctic, water gets very cold, and so freezes, leaving behind other cold water, but with a higher salt concentration.

• Therefore, this water is denser and so it sinks. Warmer water from lower lattitudes is pulled in, cooled by Polar temperatures, and so the cycle continues.

Does water or air hold heat more effectively?

Water

What are the four natural causes of climate change?

solar output, orbital changes (including axial tilt), volcanic activity, asteroid collisions

Describe how solar output causes climate change

• The sun follows an 11 year cycle. Sunspots appear and dissapear.

• At solar maximum, there are more sunspots, so more heat energy is emmitted and there is an increase in the Earth's temperature.

What are flares?

Bursts of energy that flash off of the Sun's surface - the bursts of heat radiation that are released from sunspots.

Describe how orbital changes cause climate change?

• The earth's orbit changes from circular to eliptical over a period of around 100,000 years. These are called changes in eccentricity.

• The Earth's distance from the sun is greater in an eliptical orbit, so less radiation will reach the Earth, meaning that there is a drop in temperature so an ice age may occur.

Describe how the Earth's axial tilt can affect climate change?

• the smaller the angle of axial tilt, the further the Northern hemisphere is from the sun, and so the less ice that melts.

Describe how volcanic activity can cause climate change?

• Ash released blocks the sun's radiation

• CO2 and methane contribute to the greenhouse effect

How do asteroid collisions cause climate change?

they cause massive volumes of ust to enter the atmosphere and block the sun's radiation

Describe how tree rings provide evidence for climate change

• the size of the rings is measured, the greater the size, the more the tree grew that year.

• if they grew more, there was likely more CO2 in the atmosphere that year, so the climate was warmer

• if they grew more, there was likely more CO2 in the atmosphere that year, so the climate was warmer

• there is good accuracy, but it is limited to local areas, and changes could also have been due to rain

Describe how ice cores provide evidence for climate change

• cores removed from ice show levels of different gases in the atmosphere for a certain period, like CO2 or O2 isotopes.

• shows levels of CO2 have naturally risen and fallen over time

• quite reliable because it hasn't been altered, and can provide evidence from a very long time ago

Describe how historical records provide evidence for climate change

• sources like old photos, drawings and paintings of the landscape, written records, like diaries and newspapers, and the recorded dates of regular events, such as harvests the arrival of migrating birds and blossom

• often inaccurate, because they weren't intended to record climate

• it suggests that the climate has changed regularly over the last 2000 years, and probably varied 1-1.5 degrees cooler or warmer than average.

What are the gases in our atmosphere?

78% N2

0.03% CO2

0.03% CO2

20% O2

1% H2O

Describe CO2 in our atmosphere, its sources and its changes.

• 89% of all greenhouse gases produced, warming power 1 (compared to CO2), sources include burning fossil fuels, deforestation, increased by 30% since 1850

Describe methane in our atmosphere, its sources and its changes?

7%, of all greenhouse gases produced, warming power 21 (compared to CO2), sources includecattle farming, farming rice in paddy fields, gas pipeline leaks, increased by 250% since 1850

Describe nitrous oxide in our atmosphere, its sources and its changes

• 3% of all greenhouse gases produced, warming power 250 (compared to CO2), sources include jet aircraft engines, cars/lorries, fertilisers, sewage farms, increased by 16% since 1850

Describe nitrous oxide in our atmosphere, including its sources

• 1% of all greenhouse gases produced, warming power 3000 (compared to CO2), sources include uses in industry, solvents, cooling equipment

State some statistics concerning global production of greenhouse gases

• the EU, USA and Japan emit 33% of all CO2 emmissions, China emits 29%.

• In the developing world, most people produce 1-3 tonnes of CO2 per year, compared with 10-25 tonnes per person in the developed world

• from 1880 -2012, average global temperature rose by 0.85 degrees, and sea levels rose by over 210mm

Describe 3 possible futures, concerning the environment and population growth

• high population growth, fossil fuel use, high economic growth, sea level rise of 1m

• low population growth, some renewable energy, moderate economic growth

• low population growth, renewable energy, recycling, sea level rise of 10cm

What is the focus of an earthquake?

The point in the Earth's crust where the earthquake begins

What is the epicentre of an earthquake?

the point on Earth's surface directly above the focus

Is a shallow or a deep focus earthquake more dangerous?

Shallow (less than 75km deep)

How is an earthquake caused?

1. at a plate boundary two plates move together, or past each other

2. they rub against each other, causing friction

3. this leads to a build up of pressure

4. the plates release in a jerk, sending seismic waves through the lithosphere

Which plate boundaries do earthquakes occur at?

All of them

Give examples of primary impacts of earthquakes

building damage, tsunamis, deaths, injuries, infrastructure damage, burst gas pipes

Give examples of secondary impacts of earthquakes

homelessness, increased poverty, looting or longterm unemployment

What scale is used to measure earthquakes?

Richter scale (0-10)

Where do shield volcanoes form?

divergent boundaries and hot spots

Describe shield volcanoes

• wide base, gently sloping sides

• erupt basaltic lava

• frequent but gentle eruptions

Describe basaltic lava

low silica content causes a low viscosity (runny), so lava can travel a long way before cooling

Describe composite volcanoes

• tall, steep-sided with narrow bases

• made from alternate layers of ash and lava

• erupt andesitic lava

• eruptions are rare but violent

• risks of pyroclastic flows, lava bombs

Where do composite volcanoes form?

convergent boundaries

Describe andesitic lava, and the dangers it causes

It has a high silica content, so is very viscous

This means it cools in the vent, and pressure builds up until the next eruption, when the lava shatters, forming lava bombs, as well as hot flows of ash and gas called pyroclastic flows.

Describe how volcanoes form at hotspots

1. Magma plume rises through mantle, causing base of lithosphere to melt

2. magma produces then rises through weaknesses in the crust and erupts out of the Earth's surface

3. the magma plume remains in place, but as tectonic plates move over the plume, a chain of volcanoes can form.

What is a hotspot?

Where a volcano occurs away from plate boundaries

What are the layers of the earth?

lithosphere, asthenosphere, inner mantle, outer core, inner core

Describe the asthenosphere (density, depth, state, composition)

• 3.4-4.4g/cm^3

• partially molten

• 900 - 1600 celsius

• made from peridotite

• 75-250km deep

Describe the continental crust (density, depth, state, composition)

• 2.7 g/cm^3

• solid

• air temp to 900 degrees celsius

• made from granite

• 30 - 50 km thick

Describe the lower mantle (density, depth, state, composition)

• 4.4 - 5.6 g/cm^3

• solid

• 1600 - 4000 degrees celsius

• made from, peridotite

• 250- 2900km deep

Describe the outer core

• 9.9 -12.2 g/cm^3

• liquid

• iron and nickel

• 4000 -8000 degrees celsius

• 2900 - 5270 km deep

Describe the inner core

• solid

• iron and nickel

• 5000 - 5500 degrees Celsius