- Created by: Riya.b123
- Created on: 09-02-19 14:34
- are large scale movements of air caused by differences in air pressure which is caused by differences in temperature between equator and the poles.
- move from areas of high to areas of low pressure.
- part of global atmospheric circulation loops.
What are the different climate zones around the wo
- Polar - Temperatures low all year.
- Temperate - Moderate summers & winters, low pressure belt caused by rising air, frequent rainfall.
- Tropical - Hot all the time, high rainfall, usually near equator.
- Arid (dry) - Low rainfall most of the year.
- Global Atmospheric Circulation makes some parts of the world winder than others.
- Weak in high & low pressure belts.
- Strong between pressure belts.
- Can be extremely strong when differences in between high & low pressure areas is large.
- Ocurrs when warm, wet air rises and cools.
- Air rises in low pressure belts meaning rainfall is frequent & intense e.g rainforests (The Amazon).
- Extremely low in high pressure belts e.g. Sahara Desert.
- Equator receives most energy from sun.
- Very high in high pressure areas - little clouds to block sun's energy.
- in polar regions temperature is very low.
Australia's weather compared to the UK's
- Australia - warmer than UK, hot summers & milder winters.
- Average summer temp - 33, over 40 extremely hot.
- London - Average summer temp - 23, over 30 extremely hot.
- Australia - much lower precipitation (465 mm) - Extreme (760 mm)
- UK has twice as much rainfall (1154 mm) - Extreme (1337 mm)
- Australia has stronger extreme winds than UK.
- Australia affected by tropical cyclones.
- Gales are rare in the UK.
What are tropical storms and what do they do?
- Intense low pressure weather systems with heavy rain & strong winds that spiral around at centre.
- Bring extreme weather conditions.
- Develop when sea temp is 27C or higher - warm ocean - warm moist air to cause precipitation.
- Condensation makes is powerful.
- Earth's rotation causes storm to spin.
- Storm gets stronger from energy from warm water - wind speeds increase (250km/h or more) - Damage & destroy buildings & plants.
- Flooding & mudslides.
- Most occur north & south of equator - majority in northern hemisphere.
- Number of tropical storms in Atlantic increased since 1984.
- Air & ocean currents change in the Pacific ocean.
- Every 3-4 years - weaken or reverse..
- Last for 9-12 months
- Pressure rises in Western Pacific - falls in East.
- Trades winds to weaken or reverse.
- Sinking air in Western Pacific leads to dry weather. (Drought)
- Rising air in Eastern Pacific - wet weather
- Normal conditions become extreme.
- Trade winds move to West strongly
- Cold water rises in Eastern Pacific
- Heavy rainfall & floods in West
- Less rainfall & droughts in East
- Occur 2-7 years
What is a drought & how is it caused?
- Long period when rainfall is below average
- Water supplies become depleted - people use them
- High temperatures increase rate of evaporation.
- High pressure weather system blocks depressions
- Areas most at risk - Central & Southern Africa, Middle East etc..
- Since 1950 - more droughts in Africa, Asia
Bostcastle Flash Food - 2004
- 75 mm rain fell in 2 hours.
- Lots of rain in previous weeks - ground could not absorb water
- Steep-sided valley - surface water ran into river channels quickly
- Old bridge - low arch - trees & vehicles trapped under.
- 58 properties, 4 businesses, roads destroyed, 50 cars underwater
- People couldn't evacuate - sudden
- Tourism dropped - 90% economy relied on it.
- 100 airlifted to safety, temporary accomodations, bridge rebuilt with higher arch
- Tropical storm struck South-East USA
- Storm travelled over Gulf of Mexico - got stronger
- 1800 people killed, 300,000 houses destroyed - 80% New Orleans flooded, 3 million wothout electricity.
- Coastal habitats destroyed
- 230,000 jobs destroyed, water supplies polluted with sewage & chemicals.
- 70-80% Orleans residents evcuated
- over 50,000 people rescued
- US governemnt spend over $16 billion rebuilding homes.
- Repaired & improved flood defences.
2003 - Heatwave
- Long period during which temperature is much higher than usual.
- Caused when anti-cyclones stay in the same place.
- Temperatures in UK higher than normal.
- People suffered from heat strokes, dehydration etc.
- 2000 died, 20 injured
- Livestock died - trains buckled & melted
- NHS & media gave guidance to cope
- Limitations on water use
- Speed limits on trains
- UK created "Heat Wave Plan"
Millennium Drought - Australia
- From 2001 - 2009
- Naturally had low rainfall due to global atmospheric circulation.
- Low rainfall in South-East Australia
- Climate change may have contributed
- Temperatures higher than normal
- Water levels fell
- Large impacts on farming - crop yields fell
- Vegetation loss & soil erosion
- Water conservation measures introduced
- Desalination plants
Describe the Earth's Structure
- Earth's surface (crust) split up into tectonics.
- Oceanic crust - thin & dense
- Continental crust - thick & less dense
- At centre is the core
- Inner core - solid iron & nickel
- Outer core - liquid
- Mantle around core - semi molten rock
Convection Currents & Plate Margins
- Tectonics move due to convenction currents in the mantle
- Low parts of mantle sometimes hotter than upper parts and become less dense & slowly rise
- Move towards top of mantle & cool down - more dense - slowly sink.
- Place where plates meet are called plate boundaries or plate margins.
What are the 4 different plate boundaries?
- Destructive - oceanic plate moves toward continental plate, dense oceanic plate forced into mantle - creates volcanoes & ocean trenches.
- Collision - both continental crust move towards each other, plates forced upwards - fold mountains
- Constructive - 2 plates move away from each other - magma rises & cools - new crust
- Conservative - 2 plates move sideways past each other - same direction - different speeds. Crust isn't created or destroyed.
- Caused by tension that builds up at all plate boundaries.
- Plates send shock waves (earthquake) - spread out from focus
- Waves stronger near focus - more damage
- Measured in magnitude (Mercalli Scale - effect), Richter scale (energy released)
- Shallow focus earthquake - more damage, deep focus - less damage
- Found at destructive & constructive plate margins
- Emit lava & gases & ash, form pyroclastic flows
- Volcanic activity occurs at plate boundaries
- Hotspots - intense volcanic actvity not at any plate boundaries (Earth' s crust hotter than normal)
- Composite Volcanoes - at destructive PB, steep sided, erupts thick lava, deposits layer of ash.
- Sheild Volcanoes - at hotspots or constructive PB, not very explosive, flows quickly, low gentle sided.
Pakistan Earthquake 2005
- Eurasion plate & Indian plate meet at collision PB.
- Area prone to seismic activity
- 80,000 deaths - from collapsed buildings, 10,000 injured
- Water & electricity pipelines damaged
- Disease spread
- International aid from other countries
- Medical supplies distributed
- Government money to rebuild homes
- 40,000 to new settlement
How to manage impacts of tectonic hazards?
- Early Warning Systems for earthquakes - warnings can be communicated quickly to people when shaking detected. Useful - get under cover quickly
- Predicting & monitering volcanoes - gives time for evacuation, reduces number of deaths & injuries. Seismometers can detect indications of eruption.
- Building design - earthquake/volcano resistant buildings, special foundations, specialsied pipeliness.