Geography

• Atmospheric circulation


  The large-scale movement of air by which heat is distributed on the surface of the Earth
• Cells of atmospheric circulation

  • Hadley cell
  • Ferrel cell
  • Polar cell
• Hadley cell


  Largest cell which extends from the Equator to between 30° to 40° north & south
• Ferrel cell


  Middle cell where air flows polewards between 60° & 70° latitude
• Polar cell


  Smallest & weakness cell that occurs from the poles to the Ferrel cell
• High Pressure


  Caused by cold air sinking. Causes clear and calm weather
• Low Pressure


  Caused by hot air rising. Causes stormy, cloudy weather
• Climate Zones


  • Temperate Climate
  • Tropical Climate
  • Polar Climate
  • Desert Climate
• Temperate Climate


  Mid-latitude, 50° - 60° north &south of the Equator. Here air rises and cools to form clouds and therefore frequent rainfall. e.g. UK

  
• Tropical Climate


  Found along the Equatorial belt, this zones experiences heavy rainfall and thunderstorms. E.g. Brazil

  
• Polar Climate


  Within the polar zones cold air sinks causing dry, icy and strong winds. E.g. Antarctica
• Desert Climate


  30° north and south of the equator, sinking dry airs leads to high temperatures without conditions for rainfall. E.g. Libya
• Wind


  The movement of air from an area of high pressure to one of low pressure
• Types of wind


  • Katabatic Winds
  • Trade Winds
  • Jet Streams
• Katabatic Winds


  Winds that carry air from the high ground down a slope due to gravity. e.g. Antarctic
• Trade Winds


  Wind that blow from high pressure belts to low pressure belts
• Jet Streams


  These are winds that are high in the atmosphere travelling at speeds of 225km/h
• Precipitation


  When water vapour is carried by warm air that rises. As it gets higher, the air cools and the water vapour condenses to form a cloud. As water molecule collide and become heavier, the water will fall to Earth as precipitation

  
• Extremes in weather conditions

  • Wellington, New Zealand
  • Puerto Lopez
  • The Atacama, Chile
  • Mawsynram, India
• Tropical Storms are known by many names, including hurricanes (North America), cyclones (India) and typhoons (Japan and East Asia)

  
• Tropical Storms occur in a band that lies roughly between the tropics of Cancer and Capricorn and despite varying wind speeds are ferocious storms

  
• Tropical Storms generally form where sea temperatures rise above 27°C

  
• Formation of Tropical Storms

  1. The sun's heats large areas of ocean in the summer and autumn

  2. Once the temperature is 27⁰, the rising warm moist air leads to a low pressure. This eventually turns into a thunderstorm. This causes air to be sucked in from the trade winds

  3. With trade winds blowing in the opposite direction and the rotation of earth involved (Coriolis effect), the thunderstorm will eventually start to spin

  4. When the storm begins to spin faster than 74mph, a tropical storm (such as a hurricane) is officially born

  5. With the tropical storm growing in power, more cool air sinks in the centre of the storm, creating calm, clear condition called the eye of the storm

  6. When the tropical storm hit land, it loses its energy source (the warm ocean) and it begins to lose strength. Eventually it will 'blow itself out'

  
• El Nino effect


  Normally, warm ocean currents off the coast of Australia cause moist warm air to rise and condense causing storms and rain over Australia. In an El Niño year (every 2-7 years) the cycle reverses. Cooler water off the coast of Australia reverses the wind direction leading to dry, sinking air over Australia causing hot weather and a lack of rainfall
• Drought can occur anywhere throughout the world but they are more frequent between the tropics of Cancer and Capricorn
• Global warming


  Impacting the frequency and strength of tropical storms, possibly due to an increase in ocean temperatures
• Changing rainfall and evaporation patterns related to gradual climate change

  Increasing the severity of droughts since the 1940s
• Causes of UK Heat Wave 2015

  An anticyclone (areas of high pressure) that stayed in the area in July. This blocked any low pressure systems that normally brings cooler and rainier conditions
• Effects of UK Heat Wave 2015

  • People suffered from heat strokes and dehydration
  • Fires due to lightening strikes
  • Rail network disrupted
  • Sports days cancelled
• Management of UK Heat Wave 2015

  • The NHS and media gave guidance to the public
  • Train speed limits imposed
  • Government implemented 'level 3 heatwave action'
  • Warning about open water swimming
• Causes of Typhoon Haiyan 2013

  Started as a tropical depression on 2rd November 2013 and gained strength. Became a Category 5 "super typhoon"
• Effects of Typhoon Haiyan 2013

  • Almost 4,000 deaths
  • 130,000 homes destroyed
  • Water and sewerage systems destroyed caused diseases
  • Emotional grief for lost ones
• Management of Typhoon Haiyan 2013


  • The UN raised £190m in aid
  • USA & UK sent helicopter carrier ships deliver aid remote areas
  • Education on typhoon preparedness
• A La Niña event may, but does not always, follow an El Niño event
• La Niña


  Unusually cold sea surface temperatures (3-5oC colder) found in the eastern tropical Pacific. Impacts are the opposite of El Niño, where Australia would experience droughts during El Niño, there could be an increased risk of flooding during La Niña. Likewise, Peru could experience droughts during La Niña
• La Niña could be described as a more exaggerated version of a normal year in the Pacific Ocean
• Structure of the Earth

  • The Crust
  • The Mantle
  • The Inner and outer Core

  
• The Crust


  Varies in thickness (5-10km beneath the ocean. Made up of serval large plates
• The Mantle


  Widest layer (2900km thick). The heat and pressure means the rock is in a liquid state that is in a state of convection
• The Inner and outer Core

  Hottest section (5000 degrees). Mostly made of iron and nickel and is 4x denser than the crust. Inner section is solid whereas outer layer is liquid