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Global Hazards - Coggle Diagram
Global Hazards
Climate
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Global circulation model
Effects on climate
Sinking air - High pressure - Calm, dry weather
Rising air - Low pressure - Stormy, wet weather
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Climate zones
Desert climate - Found along the tropics (30^ latitude), often experiences dry, hot weather
Temperate climate - Found at around 60^ latitude, weather is temperate with moderate rainfall
Tropical climate - Found along the equator, often experiences heavy rainfall and storms
Polar climate - Found at the poles, weather is dry and icy with strong winds
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Precipitation
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Precipitation occurs when warm, wet air rises and cools causing water vapour to condense
Typhoon Haiyan (cs)
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Responses
Short term
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1 million food packs and 250,000 litres of water delivered
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Before
Evacuation of 750,00 people
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Extreme Weather
Rainfall
Frontal / cyclonic - When warm air meets cold air, the warm air will rise above the cold air, condense into clouds and then precipitation will occur.
Relief / orographic - When water from an ocean evaporates and then meets a hill it is forced upward. This will cause rainfall on the one side of the hill and a rain shadow on the other side.
Convectional - When land warms up water vapour is evaporated and rises up. It then condenses and forms clouds which eventually precipitate returning the water to the ground.
Tropical storms
Formation
- The sun heats the ocean causing warm, moist air to rise above.
- Once the temperature is 27^C, the rising moist air causes low air pressure leading to a thunderstorm.
- With colder trade winds rushing in to fill gaps and due to the rotation of the earth, the thunderstorm will begin to spin.
- When the storm begins to spin faster than 74mph A tropical storm has formed.
- As the storm continues to grow more cool air sinks at the centre creating a calm area called the eye of the storm.
- When the storm reaches land it loses its energy source (the warm ocean) and begins to die out.
The Coriolis effect
Tropical storms will rotate clockwise in the northern hemisphere and anticlockwise in the southern hemisphere
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Droughts
Droughts are most frequent between the tropics, in areas of high air pressure and are becoming more frequent due to climate change.
A drought is a prolonged period of time with abnormally low rainfall in an area, leading to water shortage.
El Niño / La Niña
La Niña is a phenomenon that has the opposite effect of El Niño (The normal weather becomes more extreme).
El Niño is a phenomenon that occurs every 2-7 years where warm water in the South Pacific moves east due to changes in air pressure causing the trade winds to reverse. This causes stormy weather in Southern America and drought in Australia.
Eyjafjallajökull (cs)
Effects
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International
107,000 flights cancelled accounting for 48% of air traffic with over 10 million passengers
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The Earth
Tectonics
Plate boundaries
Constructive - Two plates moving away from each other creating a gap. Can cause shield volcanoes to form.
Conservative - Two plates moving past each other, can cause earthquakes.
Destructive - Subduction occurs when a continental and oceanic plate meet, the oceanic plate goes under the continental plate because it is denser. This can cause earthquakes and composite volcanoes or trenches to form.
Collision zones - To continental plates colliding, can create mountains and can cause shallow focus earthquakes.
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Volcanoes
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Fissure vents - Openings usually in the side of volcanoes through which lava erupts (little explosive energy)
Composite - Most common type of volcano, found on destructive plate boundaries. Cause destructive eruptions with viscous lava.
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Shield - Found mainly underwater on constructive plate boundaries or on hot spots. They are smaller and contain runny lava.
Earthquakes
Shallow focus - More common and damaging, seismic waves spread and causes wide spread damage.
Deep focus - Occur on destructive plate boundaries, seismic waves travel vertically causing local damage.
Epicentre - The centre of the earthquake, directly above the focus on the surface.
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