TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionSlide 1: Global atmospheric circulation

What is the global atmospheric circulation? (2marks)

Global atmospheric circulation helps to determine patterns of weather and climate.

AQA definition of Global Atmospheric Circulation:

The way that air (winds) move around the Earth’s atmosphere in a circular pattern.

Key things to remember –

• Air is heated and rises at the equator. Where air rises low pressure is left at the surface. Where air rises, it then cools and clouds form by condensation = rain.

• Air sinks back down to the surface at 30 degrees north and south of the equator. Where air sinks this causes an area of high pressure at the surface. There is no condensation = dry (deserts)

• This circulation creates weather conditions on Earth.

North Pole (90°N)

South Pole (90°S)

60°N

60°S

30°S

30°N

2. Warm air rises.

3.The rising air cools and condenses leading to clouds and rain.

1. The sun heats the air at the equator.

4. The air then divides and moves north and south until it reaches 30°N and S.

5. This air then sinks back down to the surface. There s no condensation therefore these areas are dry = deserts.

6. Some of the air heads back to equator and some moves towards 60°N and S. This movement of air nearest the surface is what we know as wind.

7. Two further cells exist further North and South

Model of Atmospheric circulation

EQUATOR 0°

North Pole (90°N)

South Pole (90°S)

60°N

60°S

EQUATOR 0°

30°S

30°N

Model of Atmospheric circulation with surface winds added

LOW PRESSURE

HIGH PRESSURE

LOW PRESSURE

HIGH PRESSURE

LOW PRESSURE

HIGH PRESSURE

HIGH PRESSURE

Trade winds

Trade winds

PREVAILING WESTERLIES

PREVAILING WESTERLIES

© Rob Gamesbyhttp://www.coolgeography.co.uk

The global distribution of tropical storms:

• Most tropical storms occur between the Tropic of Cancer in the north and the Tropic of Capricorn in the south. (we call the area between these two lines of latitude the tropics.)

• Tropical storms are called different things depending on where they are: Examples are:

• Hurricanes = Atlantic Ocean

• Typhoons in the western Pacific

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionSlide 1: The formation of tropical storms

Describe the distribution of tropical storms. (2marks)Give one thing needed for a tropical storm to form. (1mark)What is a tropical storm. (2marks)

A tropical storm is a spinning mass of clouds reaching wind speeds of 75 miles per hour or higher and bringing heavy rain.

Tropical storms need the following to form:

• Ocean temperatures of at least 27 degrees C.

• Sea depth of 60-70m

See the following slide for the sequence of formation.

When wind speeds reach 75miles per hour it becomes a tropical storm.

The storm is carried across the ocean by winds and gains strength.

The tropical storm will lose its energy when it travels over land and therefore loses its source of heat and moisture from the ocean. Land will also slow the storm down due to friction.

1. The sun heats

the air at the

surface.

2. This warms the

oceans to 27°C

3. This moist, war air rises.

4. The air cools and

condenses forming

clouds.

5. Some cooled

air sinks back

down helping to

create the EYE

EYE

CUMULONIMBUS

CLOUDS

6. Air rushes in

from outside of

the storm

creating winds

7. The whole storm

rotates because of

the Earth’s spin

The formation of tropical storms and hurricanes

Step 1• The sun warms air and oceans at the surface.

Step 2• This warms the oceans to 27°C

Step 3• Moist, warm air rises.

Step 4• Rising air cools and condenses forming clouds = rain

Step 5• Some cooled air sinks back down helping to create the EYE

Step 6• Air rushes in from outside the storm forming winds.

Step 7• The whole storm rotates because of the Earth’s spin

Rain bands

Warm Ocean Water (27°C+)

400 to 600km

EYE

About12KM

Anvil of Cumulonimbus clouds

Warm upwelling air

Cooler sinking air

Spiral of fastest winds around the eye wall

Spiral bands of thunderstorms

Features of a tropical storm:

Line of cross section©Rob Gamesby http://www.coolgeography.co.uk

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionSlide 9: Features of a tropical storm:

Explain the formation of a tropical storm. (4marks)Describe weather conditions in the eye of the storm. (1mark)

The eye…

…is the centre at the storm where relatively cold air sinks. There are no clouds and conditions are calm.

The eye wall…

…is a tall bank of cloud surrounding the eye. Here are found the strongest winds in the storm over 75 miles per hour, heavy rain, thunder and lightning.

Beyond the eyewall there are further banks of clouds with thunderstorms and occasionally tornados. There will be strong, gusty wind and heavy rain.

The hurricane spins due to the Coriolis effect – (winds bending because of the spin of the Earth.)

Depending on whether the hurricane forms in the northern or southern hemisphere the winds bend in different directions.

In the northern hemisphere clouds swirl anti-clockwise and in the southern hemisphere they go clockwise – exactly the same as water down your plughole!

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionSlide 10: Features of tropical storms

Describe how weather conditions might change as a tropical storm passes over an area. (4marks)Give one reason why tropical storms may eventually lose their energy. (1mark)

This is a satellite image of a tropical storm.

We know it is in the northern hemisphere because it is spinning anti clockwise.

Beyond the eyewall there are further banks of clouds with thunderstorms and occasionally tornados. There will be strong, gusty wind and heavy rain.

The eye is the centre at the storm where relatively cold air sinks. There are no clouds and conditions are calm.

The eye wall is a tall bank of cloud surrounding the eye. Here are found the strongest winds in the storm over 75 miles per hour, heavy rain, thunder and lightning.

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionSlide 11: How will climate change affect tropical storms?

Questions to do with this are likely to be about describing trends on graphs. Key terms to use: increasing, decreasing, fluctuating. Remember to give figures from the graph and if you can, manipulate figures (e.g. increased by how much?)

Global temperatures have risen over the last few decades. How will this affect tropical storms?

We don’t know for sure but it might affect their intensity, frequency and distribution.

1. What is intensity?

The destructive power of the storm.

Climate change is expected to lead to more intense tropical storms as the increase in sea temperatures leads to an increase in windspeed.

2. What is frequency?

This is how often they occur.

Again, this is uncertain. Some evidence suggests the frequency of tropical storms might decrease in the future.

3. What is distribution?

The locations that experience tropical storms.

Tropical storms may occur in other areas outside the tropics as sea temperatures rise e.g. South Atlantic.

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionSlide 12: The effects of tropical storms

Give two primary effects of tropical storms. (2marks)Describe the secondary effects of tropical storms. (4marks)For a tropical storm you have studied were the primary or secondary effects more severe? (9marks)

What are primary effects?

AQA definition:

The initial impact of a natural event on people and property. Refer to:

Death, injury, damage, destruction.

What are secondary effects?

AQA definition: The after-effects that occur as indirect impacts of a natural event, sometimes on a longer timescale such as disease caused by contaminated water supplies.

Other examples include children’s education suffering because they can’t go to school. People being made homeless as a result of their houses being damaged.

Effects can also be classified as…

Economic (money and jobs), social (people – housing, healthcare, education, crime) and environmental (surroundings)

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionSlide 13: Responses to tropical storms

Describe the immediate responses to tropical storms. (4marks)

Responses are what people do after the event to try to cope with it.

They can be divided into immediate and long term responses.

What are immediate responses?

AQA definition: The reaction of people as the disaster happens and in the immediate aftermath.

(Think within the first month.) Some examples are…

• Rescuing people who might be trapped.

• Burying bodies and trying to help the injured.

• Setting up temporary tents and shelters. Supplying food and water to people who need it.

What are long term responses?

AQA definition: Later reactions that occur in the weeks, months and years after the event. Examples are…

Rebuilding damaged buildings and areas.

Repairing infrastructure such as roads and water supplies

Putting in place education/building regulations to reduce the damage done next time.

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionSlide 14: Named example of a tropical storm: Typhoon Haiyan

Discuss the effects on people and the environment of a tropical storm you have studied. (9marks) (One way of discussing effects is to look at whether the effects on people or the environment were more significant. Another way is to look at whether the primary or secondary effects were more significant.)

Location:

Philippines

Year:

2013

Strength:

Category 5 storm. Winds up to 170mph. This was a “super typhoon”

Primary effects:

• 6300 people died

• 40,000 homes damaged or flattened.

• 90% of the city of Tacloban was destroyed by a storm surge with 15m high waves.

• 30,000 fishing boats destroyed.

• Key infrastructure such as powerlines and the airport was damaged.

• Crops destroyed.

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionSlide 15: Named example of a tropical storm: Typhoon Haiyan

Using an example, assess the extent to which primary effects are more significant than secondary effects. (9marks)

Secondary effects:

• Millions were made homeless.

• Three quarters of farmers and fishers lost their income.

• Aid was cut off to remote communities by blocked roads.

• Flights were disrupted for weeks, slowing down aid.

• The damage to hospitals, schools, shops and other buildings affected people’s livelihoods and education.

• Lack of food led to looting.

• Fresh water was contaminated with sewage which led to diseaseg.

• Crops such as rice were destroyed which led to prices increasing.

• There was an oil leak that damaged mangroves.

• The effects lasted a long time – 3-5 years.

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionSlide 16: Named example of a tropical storm: Typhoon Haiyan

Immediate responses:

• International government and aid agencies responded quickly by supplying food, water and temporary shelters.

• Evacuation centres set up for the homeless.

• UK government sent shelter kits.

• France and Belgium set up field hospitals to help the injured.

Long term responses:

• UN and many countries such as UK donated gave money and supplies.

• Rebuilding of roads, bridges and airport facilities.

• Ppeople were paid to clear debris.

• Rice farming and fishing were quickly re-established helped by Aid Agencies such as Oxfam helping to replace fishing boats.

• Homes have been rebuild away from areas at risk from flooding.

• More typhoon shelters have been built to help cope with future Typhoons.

Assess the effectiveness of the responses to a tropical storm you have studied. (9marks) My suggestion here would be to describe the responses and how they helped but also recognise that remote areas were difficult to get to and therefore the responses were less effective in some places than others.

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionSlide 17: Reducing the effects of tropical storms

Discuss how the effects of tropical storms can be reduced. (9marks) My suggestion here would be to cover the different types of management strategies (monitoring+prediction, planning, protection) and make a comment about how they might help and any problems associated with them e.g. less effective in remote areas and less money available in some areas to improve housing etc.

This can be done by monitoring, prediction, protection and planning.

What is monitoring?

Recording physical changes, such as tracking a tropical storm by satellite, to help forecast when and where a natural hazard might strike.

What is prediction?

Trying to say when a tropical storm will happen

What is protection?

What can be built to protect people?

What is planning?

Thinking ahead and coming up with ways to reduce the impacts of tropical storms such as having evacuation plans in place.

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionSlide 18: Reducing the effects of tropical storms

Monitoring and Prediction:

• Tropical storms can be monitored by satellites.

• The agencies identify the formation of tropical storms and track their paths and strength.

• Monitoring information can be used to provide warnings which allow local areas to prepare.

• Despite advances in scientific methods, accurate prediction is not always easy because the strength and path of a storm can change quickly

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionSlide 19: Reducing the effects of tropical storms

Planning:

• As methods of forecasting have improved, so have the ways in which people prepare for a storm.

• Schoolchildren are taught about the dangers of tropical storms and what to do if a storm hits.

• Governments produce posters, leaflets and information for the media.

• People are encouraged to prepare disaster kits.

• Governments have evacuation plans in place

• Long term response plans include rebuilding roads and rehousing people who lost their homes.

• Health services need to prepare for plan for long term health effects such as psychological problems.

Protection:

• Sea walls built which can protect people from storm surges.

• Buildings can be strengthened by reinforcing windows, doors and roofs, Houses close to the coast can be built on stilts.

• Cyclone shelters can be built where people can go during a tropical storm.

• Mangroves along the coast can reduce the impact of storm surges.

Assess the extent to which prediction is the most important way of reducing the effects of tropical storms. (9marks)

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionSlide 20: An overview of the types of weather hazard experienced in the UK

What is weather?

The day to day conditions of the atmosphere.

What is climate?

The average weather over a long period of time (at least 30 years)

What is extreme weather?

When weather is different (usually worse) that the normal weather conditions in a country such as an unusually hot or cold period.

Examples of extreme weather hazards in the UK:

1. Thunderstorms- heavy rainfall with thunder and lightning can lead to flash flooding. Example:

July 2014 electrical storms – 3000 lightening strikes across southern Britain.

2. Prolonged rainfall – rain lasting a long time can also lead to floods e.g. wet winter in 2014 – southern England.

Outline the types of weather hazard experienced in the UK. (4marks)

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionSlide 21: An overview of the types of weather hazard experienced in the UK

3. Drought and extreme heat – long spells of dry, hot weather can lead to rivers drying up and reservoirs becoming dangerously low which affects water supplies and wildlife. Example?

2003 heatwave across UK and rest of Europe.

4. Heavy snow and extreme cold – Example?

2018 feb-march “beast from the east” brought extreme cold and snow to much of the UK.

5. Strong winds – sometimes the UK gets remnants of hurricanes from across the Atlantic. These can cause fallen power lines and trees. Example:

The remnants of storm Ophelia 2017.

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionSlide 22: An example of a recent extreme weather event in the UK – Somerset Levels Floods in 2014

Discuss the impacts of an extreme weather even in the UK. (9marks) (One way of discussing would be to say whether they were mainly economic, social or environmental.)Explain the causes of an extreme weather event in the UK that you have studied. (4marks)

Somerset is a county in south west England.

The area is very low lying and is used for farming.

Causes of the floods:

1. Heavy and prolonged rainfall – the wettest January since records began in 1910. 350mm rain fell in January and February.

2. High tides and storm surges swept up the rivers.

3. Rivers had not been dredged (cleared of sediment) for 20 years and had become clogged up with sediment.

Social impacts of the floods:

• 600 houses flooded.

• 16 farms evacuated.

• Residents evacuated to temporary accommodation for several months.

• Villages e.g. Moorland were cut off – affected peoples lives e.g. attending school and shopping affected.

• Power supplies cut off.

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionSlide 23: An example of a recent extreme weather event in the UK – Somerset Levels FloodsEconomic impacts:

• Cost of flood damage - £10million.

• Agricultural (Farming) land was under water for 3-4 weeks.

• 1000 livestock evacuated.

• Local roads and power supplies were cut off.

• The Bristol to Taunton railway line closed at Bridgewater.

Environmental impacts:

• Floodwaters were contaminated with sewage and other pollutants such as oil and chemicals.

• Debris left on the land

• Stagnant water sitting there for months had to be reoxygenated before being pumped back into rivers.

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionSlide 22: An example of a recent extreme weather event in the UK – Somerset Levels Floods

Assess the effectiveness of management strategies used in the aftermath of an extreme weather event in the UK you have studied (9marks)

How management strategies can reduce the risk:

In the immediate aftermath:

• People affected coped however they could e.g. using boats to go shopping or attend school.

• Local volunteers and community groups helped those in need.

In the longer term – a £20million flood action plan has been launched by Somerset County Council.

• In March 2014, rivers such as the Parrett were dredged to reduce the risk of flooding – there are question marks over the effectiveness of this technique!

• Road levels have been raised in places so they wont flood in future flood events.

• Flood defences will be used to protect vulnerable communities such as Moorland.

• River banks are being raised and strengthened and more pumping stations being built.

Climate change and possible sea level rise will mean that flooding events in the area in the future become increasingly difficult to manage.

Many local people have criticised the government of not doing enough to protect the area.

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionSlide 25: Evidence that weather is becoming more extreme in the UK

Suggest evidence to show that weather in the UK is becoming more extreme. (4marks)

Extreme weather events seem to be on the increase in the UK and many records have been broken recently. Examples include:

Feb-march 2018 – “The Beast from the East” (cold air from Siberia) brought cold temperatures and snowfall to much of the UK.

December 2015 was the wettest and warmest December on record = storms and flooding.

2014 England’s wettest winter in 250 years. Heavy and prolonged rainfall led to the Somerset Levels floods.

2003 – heatwave. UK recorded its highest ever temperature in Kent – 38.5 degrees C.

Why might UK weather be becoming more extreme?

It could be linked to climate change. For example:

• More energy in the atmosphere increases the intensity of storms.

• The atmospheric circulation may be affected bringing floods to dry regions and heatwaves to cooler areas.

In 2011, the Intergovernmental Panel on climate change concluded that extreme weather would become more common as global warming occurs.

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionKey facts quiz:

What ocean temperatures are required for tropical storms to form?

27 degrees C.

What sea depths are required for tropical storms to form?

60-70m

What windspeed does a storm have to reach before it is classified as a tropical storm?

75mph

Which country did Typhoon Haiyan mainly affect?

Philippines

In what year was typhoon Haiyan?

2013

What windspeeds were reached in Typhoon Haiyan?

175mph (a super typhoon)

How many people died in Typhoon Haiyan?

6300

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionKey facts quiz:

How many homes were damaged or destroyed?

40,000

90% of which city was destroyed by the storm surge?

Tacloban

How many fishing boats were destroyed?

30,000

How many people lost their source of income?

6million

How many tonnes of crops were destroyed?

1.1 million

By 2014, how much had rice prices risen by?

10%

How many evacuation centres were set up after the typhoon?

1200.

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionKey facts quiz:

In what year were the Somerset Levels floods?

2014

How much rain fell in January and February?

350mm

How long had It been since rivers were dredged?

20 years

What was the cost of the damage?

£10million

How many houses were flooded?

600

Name a village that was badly affected?

Moorland

How many people died?

0

Name a river that has since been dredged.

Parrett

TOPIC: The Challenge of Natural Hazards – Weather Hazards sectionKey facts quiz:

Give an example of extreme cold weather and snow in the UK.

Feb-march 2018 snow and temperatures well below 0 for much of the UK for at least a week.

Give an example of extreme rainfall in the UK.

2014 – heavy and prolonged rainfall in Somerset led to the Somerset levels floods.

Give an example of extreme hot weather in the UK.

2003 hottest temperature recorded in Kent – 38.5 degrees. Heatwave across the UK and the rest of Europe.