Climate change

• The 3 atmospheric cells

  • Hadley
  • Ferrel
  • Polar
• Global circulation

  1. Hot air rises at the equator creating a low pressure belt

  2. As the air rises it cools and condenses

  3. The cool air moves from the equator 30 degrees north and south of the equator where the air sinks creating a low pressure belt with no clouds and rainfall

  4. The cool air reaches the surface and moves as surface winds either to the equator or to the poles

  5. At 60 degrees north and south of the equator, the warmer surface winds meet the colder air from the poles

  6. The warmer air is forced to rise creating low pressure and rain

  7. At the poles the cool air sinks creating high pressure

  8. Air in this area of high pressure is drawn back towards the equator as surface winds
• Surface winds:

  • Winds blowing towards the equator are called trade winds
  • Trade winds blow from SE in the southern hemisphere and NE in the Northern hemisphere
  • At the equator trade winds meet and heat from the sun causes them to rise and form clouds
  • Surface winds blowing towards the poles are called westerlies
  • Westerlies blow NW in the Southern hemisphere and SW in the Northern hemisphere
• Ocean currents:

  • Ocean currents are large scale movements of water that transfer heat energy from warmer to cooler regions
  • Surface currents are caused by winds and help transfer heat away from the equator
• Deep ocean currents:

  1. When water freezes at the poles the surrounding water gets saltier, increasing it's density
  2. As it get's denser it sinks causing warmer water to flow in at the surface
  3. This warmer water is cooled and sinks. This cycle moves the water in a big loop around the
• Quaternary period

  • Lasted 2.6 million years to present day
  • Before the Quaternary period the Earth climate was warmer and quite stable
  • Global temperatures have shifted between glacial periods (100,000 years long) and warmer interglacial periods (10,000 years long)
• Ice cores:

  1. Ices cores are made up of layers (1 layer = 1 year)
  2. Scientists drill into into ice sheets to get long cores of ice
  3. By analysing the gases trapped in the ice you can tell what the the temperature was each year
• Tree rings:

  1. As a tree grows it forms a new ring each year
  2. if the tree rings are thinner then the climate was cooler, if the tree rings are thicker then the climate was warmer
• Milankovitch cycles- Stretch

  • The path of the Earth's obit around the sun changes from an almost perfect circle to an ellipse (oval) and back again every 96,000 years
• Milankovitch cycles- Tilt

  • The earth it tilled at an angle as it orbits the Sun. The tilt changes over a cycle of 41,000 years
• Milankovitch cycles- Wobble

  • The axis of the Earth wobbles like a spinning top on a cycle of about 22,000 years
• Solar Variation

  1. The Sun's output of energy changes in cycles of 11 years
  2. Sunspots are cooler areas of the sun that are visible dark patches which increases the Sun's output of energy
  3. The less sunspots the cooler the Earth's climate
• Volcanic activity

  1. During eruptions large amounts of material enter the atmosphere.
  2. Some of theses particles reflect the sun rays so the Earth cools
  3. This causes short term climates changes
• Greenhouse effect

  1. The atmosphere allows the heat from the Sun (short-wave radiation) to pass through to heat the Earth's surface.
  2. The Earth's surface then gives off heat (long-wave radiation).
  3. This heat is trapped by greenhouse gases which radiate the heat back towards Earth.
  4. This process heats up the Earth.
• Human activities making Greenhouse Effect stronger:

  1. Industrial process need energy (industry)
  2. landfill sites release methane (industry)
  3. Rice paddies and cows produce methane (farming)
  4. Vehicle release greenhouse gases (transport)
  5. Fossil fuels release carbon dioxide when burnt (energy)
• Negative affects of climate change:

  • Warmer sea means the sea expands and sea levels rise
  • Melting glaciers means sea levels rise risking costal areas
  • More frequent droughts means problems with farming
• UK climate history

  • Medieval warm period (900-1300)
  • Little ice age
• Continentality in the UK

  • Areas of the UK near the sea are warmer in winter
  • This is because the sea stores heat energy from the summer
  • Areas of the UK near the sea are cooler in the summer
  • This is because the sea takes a long time to heat up so the land cools down
• North Atlantic Drift

  • An ocean current that brings warm water firm the Caribbean to the W=west coast of the UK across the Atlantic
  • This means the west coast is warmer
• Air masses

  • Arctic and polar form at high latitudes (warm)
  • tropical from at low latitudes (cool)
  • Maritime form over oceans (wet)
  • Continental form over land (dry)
• UK Air masses

  Arctic Maritime - cold and wet (North)

  Polar Continental - cold and dry (North East)

  Tropical Continental - warm and dry (South East)

  Tropical Maritime - warm and wet (South)

  Polar Maritime - cold and wet (South West)