Geog Paper 1

• Ecosystem


  Community of living + non-living things that interact
• Food chain


  1. Energy is passed from plants (producers) to herbivores to carnivores to top predators

  2. Energy is lost through breathing, movement and excretion

  3. When one part of the food chain is removed, other elements are affected, possibly causing extinction
• Food chain example

  • grass → rabbit → fox
  • Nut tree→ ants→ spider→ praying mantis → bird→ snake
• Water cycle


  1. Sun's rays evaporate water

  2. Water vapour condenses into clouds

  3. Precipitation falls as rain

  4. Water infiltrates soil and rock

  5. Evapotranspiration

  6. Surface runoff into rivers
• Characteristics of tropical rainforests


  • Layered structure with little growth on forest floor
  • Thin, infertile soil as nutrients are quickly recycled
  • Humidity causes rapid decomposition and growth
• When trees are cut down in the rainforest


  • Main nutrient store of leaves and fruit is lost, soil quickly loses fertility
  • Roots no longer hold soil together, soil erodes causing flooding
• Threats to the rainforest


  • Logging for timber
  • Mineral extraction
  • Agriculture and cattle ranching
• Solutions for protecting the rainforest


  • Monitoring with satellite images
  • Eco-tourism
  • Afforestation
• Characteristics of polar areas


  • Low temperature, low rainfall
  • Small, slow growing plants
  • Not very biodiverse
• Threats to polar areas


  • Oil and gas exploration
  • Fishing and whaling
  • Shipping
  • Tourism
• Solutions for protecting polar areas


  • Antarctic Treaty
  • Svalbard Islands protection
• Nutrient cycle


  1. Plants take up nutrients from soil

  2. Leaves and dead animals decompose to release nutrients back into soil

  3. Soil is a mix of broken down rock and rotten organic matter

  4. Nutrients can be artificially added through fertilisers
• Global circulation system


  The global circulation of air masses creates pressure belts and cause different weather conditions in different global locations. The air masses move in cells and these determine weather conditions.
• Air cells


  • Hadley Cells
  • Ferrel cells
  • Polar Cells
• Hadley Cells


  • Hot air rises at the equator creating low pressure, the air descends at 23⁰ N+S creating low pressure
• Ferrel cells


  • Air descends at 23⁰ N+S creating high pressure and rises at 60⁰ N+S creating low pressure there
• Polar Cells


  • Air rises at 60⁰ N+S and descends at the Poles
• High pressure


  Dry, calm conditions
• Belts of high pressure at 23⁰ N + S of the equator


  Create dry and arid landscapes, where many deserts are found
• Low pressure


  Wet, stormy conditions
• Belts of low pressure along the equator and 60⁰ N/S


  Creates rainy conditions
• Temperature is higher at the equator


  So hot + wet =tropical rainforests
• Temperature is milder at 60⁰ N


  So mild + wet= deciduous forest
• Tropical storms


  • Sea surface temperature is at or above 26.5 degrees C, sea is at least 60metres deep
  • Water from the surface of the sea evaporates and the warm air rises
  • This leaves an area of low pressure over the sea
  • The Coriolis effect makes the winds spin and more water droplets evaporate from the ocean
  • All of the evaporated water droplets form heavy clouds as they condense in the atmosphere
  • The storm reaches land and its energy dissipates
• Droughts are prolonged periods of no rain (high pressure)
• Saharan Africa and middle east are at risk of droughts
• Tropical storms are also known as typhoons or hurricanes
• Droughts


  More droughts expected in the future as climate change alters the predictability and amounts of rainfall
• Tropical storms


  The frequency may not change, but as climate changes, the severity may increase
• Extreme wind


  • Australia has stronger extreme winds than the UK as it experiences tropical cyclones (wind speeds around 118 km/h)
  • The UK gets gales although rarely- wind speeds around 62km/h
  • Strongest wind recorded in Australia= 400 km/h
  • Strongest wind recorded in the UK= 220km/h
• Extreme temperature


  • Australia is has higher temperatures in summer and less extremely cold winters than the UK
  • Max summer temp in Australia is 33⁰C, more than 40⁰C is considered hot
  • Max summer temperature in London is 23⁰C, over 30⁰C is considered hot
• Extreme precipitation


  • The UK has much more precipitation (rain) than Australia
  • Australia average annual rainfall is 465mm, the UK gets twice as much at 1150mm
  • In Australia, over 550m is considered extremely wet, over 1210 mm in the UK is considered extremely wet
• El Nino


  The reversal of normal trade winds over the Pacific Ocean
• Normal year: trade winds go east from S. America to Australia


  Bringing low pressure (rain) in Australia and high pressure in South America (dry conditions)
• El Nino year: trade winds reverse


  So low pressure (rain) in S. America leading to flooding/landslides and high pressure (dry conditions) to Australia leading to drought and wildfires
• El Nino


  Also leads to more storms in the Pacific Ocean and less storms in the Atlantic Oceans
• La Nina


  Years are where the normal weather patterns are more intense leading to higher than average rainfall in Australia (flooding)
• Flash flooding: Boscastle


  • High rainfall: the amount of rain than normally fell in a month fell in 2 hours
  • Heavy rain in previous weeks= saturated soil which led to rapid run off
  • The village is in a steep sided valley = fast flow into the river
  • Confluence of 3 rivers nearby = more water in the rivers quickly
• Drought: Australia


  • Australia is in a high pressure zone (very dry) it is at 30⁰ S of equator
  • El Nino in 2002-3, 2004-5 and 2006-7 meant less rain= unusually dry
  • Climate change= made Australia warmer than usual and drier than usual as rain moved to South America
• Earth's structure


  • Crust: outer layer of earth. Oceanic crust (7km deep) and continental crust (35km deep)
  • Mantle: made of molten rock- the thickest layer of the earth
  • Outer core: temperatures reach 4000°C
  • Inner core: made of solid iron and nickel, temperatures reach 6000°C