Geography 1

• Explain how the global atmospheric circulation system redistributes and transfers heat energy from the Sun around the Earth


  Hot air rises and moves either north or south, cool air sinks whoch warms up as it falls (convection currents)
• Name the 3 atmospheric circulation cells

  Polar, Ferrell, Hadley
• Explain how the global ocean currents redistributes and transfers heat energy from the Sun around the Earth


  E.g. the Gulf Stream (originates in Atlantic to North-west Europe), process of convention currents: warm water from equator, cool water from the poles, i.e. the global conveyor belt
• Explain how asteroid collisions are natural causes of climate change

  Cause global cooling as particulates in atmosphere block sunlight, effects could last 5-10 years, but asteroid must have diameter of over 1 km (once every 500,000 years), e.g. 1908 asteroid exposition over Russia, but not big enough to alter global climate
• Explain how volcanic eruptions are natural causes of climate change

  Cause global cooling as particulates in atmosphere block sunlight, effects could last 1-2 years, e.g. Krakatau eruption in Indonesia, big eruptions are uncommon (once every century)
• Explain how sunspots are natural causes of climate change

  More/less solar energy, 11 year cycles, alter temperature by 1-2°C
• Explain how the Milankovitch cycle is a natural cause of climate change

  Orbital changes, or axis tilt, 100,000 years for changes to occur, results in ice ages, or warm periods
• Climate graphs


  Line=temperature, bars=precipitation
• Sources of evidence for last climate change

  Photographs, paintings, diaries, clothings, food (crops grown or animals hunted), ice cores (carbon analysis), pollen analysis, tree rings
• Past climate changes from Roman times to present day (quaternary period)


  Medieval warm period from 0-1500, 1500-1800=Little Ice Age, 1800-present day: modern global warming (Industrial period); glacial period (100,000 years), interglacial period (10,000 years)
• Where is the Hadley cell found?

  Between 30° and 0° latitude
• Where is the Polar cell?

  60°-90° latitude
• Where is the Ferrell cell?

  30°-60°
• Where does low air sink?

  30° latitude
• Where does hot air rise?

  0° latitude and 60°
• How has human activities enhanced greenhouse effect

  Industry, transport, energy and farming produces greenhouse gases
• How has the enhanced greenhouse effect led to global warming

  More gases to trap radiation from the sun
• Evidence for human activity causing climate change

  Increased rate of rising sea levels, warming oceans, global temperature rise, declining Artic sea ice, extreme weather evenets
• Possible global warming consequences for people

  Food scarcity (more droughts/floods, so lower crop yields), more frequenct extreme weather events, loss of coastal areas, more deaths due to heat exhaustion, problems with water availability
• Reasons for range of projection for global temperature change and sea level rise in the future

  Influenced by the undependable nature of population growth, use of fossil fuels, people's lifestyles (using resources)
• How are tropical cyclones formed

  1. Band of low pressure where the trade winds meet

  2. Warm air and water rise, condense to form thunderclouds

  3. A depression formed due to the rising warm air, depression grows in size as the air is drawn in

  4. Winds spiral due to the coriolis force, eye of the storm formed as the cold air descends in centre
• What causes tropical cyclones to intensify?

  Warm ocean temperatures (26.5°C +), high humidity, low wind shear/strong winds, Coriolis force
• What causes tropical cyclones to dissipate?

  Losing energy (from humidity and rising warm water vapour from oceans) moving inland, high pressure systems deflect hurricane path to cooler waters
• Structure of tropical cyclones

  Up to 1000 km radius from eye, cloud top height up to 15 km, cumulonimbus clouds
• What is a hurricane?

  Low pressure storm systems in tropical or sub-tropical waters
• How does the seasonal global distribution of tropical cyclone vary?


  Summer and late autumn (due to warm ocean temperatures)
• Physical hazards of tropical cyclones, Cyclone Alia, Bangladesh (LIC)


  Estuary region received 120 mhm of rain in few hours, wind strength 360 km/hr, low pressure caused huge storm surge, landslides, suburban mangroves flooded - loss in rare tigers
• Physical hazards of tropical cyclones, Hurricane Sandy, USA (HIC)


  Storm surges (coastal flooding), strong winds (Category 2 - 96 mph), intense rainfall
• How did Bangladesh prepare for cyclone Alia?

  Weather forecasting: issued weather forecasts and warning on TV, satellite technology: 3 radar systems, but not enough people had access to TV and radio digital systems
• How did USA prepare for Hurricane Sandy?

  Warning systems: used to prepare people in New York (costliest storm in US history because of damage), evacuation systems in place, e.g. Fort Myers in Florida classified into risk zones, storm surge fences such as beach nourishment to weaken wave energy
• Lithosphere


  Uppermost layer of the earth, includes continental (granite) and oceanic crust (basalt) and top of mantle
• Asthenosphere


  Earth's mantle, semi-molten layer underneath tectonic plates, composition: peridotite
• Outer core


  Liquid, iron and nickel
• Inner core


  Solid, dense centre of the Earth
• What causes tectonic plates to move?

  Convention currents in the mantle (heat generated by radioactive decays from Earth's core)
• Divergent plate boundary


  Plates pulled aprt
• Convergent plate boundary


  Plates collide (sometimes slips under, or rise to form mountain ranges)
• Conservative plate boundary


  Plates slide past each other
• Features of shield volcanoes

  Low, wide cone/gentle slopes, basaltic lava, frequent and gentle eruptions, constructive plate margin, e.g. Surtsey, Iceland
• Features of composite volcanoes

  High with narrow base/steep slopes, fewer eruptions with pyroclastic flows, destructive plate margins, e.g. Mount St Helens, USA