C11- the earths atmosphere

• What gases are present in the atmosphere today

  • 78% nitrogen
  • 21% oxygen
  • Other gases - carbon dioxide, water vapour and other gases such as argon
• how long have gases in the atmosphere stayed constant for

  200 million years
• How old is earth

  4600 million yers
• How did water vapour enter the atmosphere

  • in the first billion years there was intense volcanic activity Which released gases which form our atmosphere such as water vapour
  • As earth cooled water vapour condensed to form oceans
• how did carbon dioxide enter the atmosphere

  • volcanos released huge amounts of Carbon dioxide
  • Early stage earths atmosphere consisted mainly of co2 with little or no oxygen
  • Was alike to atmosphere of mars and Venus
• old atmosphere vs new atmosphere

  old - mostly carbon dioxide and small, increasing nitrogen

  new- 78% nitrogen, 21% oxygen and other gases
• How did the atmosphere change - carbon dioxide

  • Water vapour is condensed to oceans
  • Some carbon dioxide dissolved in oceans to form weak acids
  • This reacts with minerals to form Precipitates
  • over time this formed sediments of carbonate rock on the sea bed
  • Some of the carbon dioxide was used to make corals and shells
  • When these died they formed limestone - removing co2 from atmosphere
• How did the atmosphere change - oxygen

  • 2.7 billion years ago photosynthetic algae first evolved in the oceans
  • photosynthesis released oxygen
  • plants evolved over billions of years
  • At some point oxygen reached levels where animals could evolve
  • Photosynthesis also takes in carbon dioxide
  • This carbon can be trapped in fossil fuels causing co2 levels to fall
• what are fossil fuels

  • formed over millions of years
  • Non-renewable
• how is coal formed

  • remains of fears and trees
  • if they die in marshy wetlands they don't decompose due to lack oxygen or acidic conditions
  • these prevent bacteria from carrying our decomposition
  • over time remains are covered in sediment and compressed
  • high temp and pressure creates coal
• how is oil formed

  • crude oil formed from plankton
  • when they die they settle in mud on sea bed
  • without oxygen they don’t decompose
  • over time compressed by sediment
  • heat and pressure convert them to crude oil
• how is gas formed

  • natural gas is mainly hydrocarbon methane
  • found near deposits of oil - formed from plankton
• How much of out atmosphere is carbon dioxide

  0.04%
• what are greenhouse gases

  water vapour, carbon dioxide and methane
• what is the greenhouse effect

  • energy form the sun travels to the earth as short wavelength radiation (uv and visible light)
  • some of the short wavelength radiation reflects back into space but most passes through the atmosphere
  • short wave length radiation does not interact strongly with the gas molecules in the atmosphere
  • the energy of the radiation is absorbed when it reaches the surface of the earth
  • the surface of the earth now radiates the energy as long wave length radiation (infra-red)
  • some long wave length radiation interacts with greenhouse gases molecules
  • energy in radiation is absorbed because its trapped in the atmosphere
  • causes the temp of the atmosphere to increase
• Benefits of greenhouse effect

  Keeps temp on earth warm enough to support life
• negatives of climate change

  • melting of polar ice sheets and glaciers leading to increased sea levels leads to more flooding
  • More severe weather
  • Change distribution of animals and insect born diseases
• what is peer review

  scientists look over other findings and detect false claims
• What is carbon footprint

  The total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event
• how can we reduce carbon dioxide emissions

  • insulating homes or turning down heating
  • use public transport
  • switch to renewable electricity sources
• how to reduce electricity emissions at home

  • energy-saving lightbulbs
  • turn appliances off at plug
• problems with carbon reducing solutions

  • expensive and people are reluctant to pay
  • inconvenient
• how to reduce methane emissions

  • eat less beef and dairy products
  • trapping methane and burning it to produce electricity from landfills - costs money
• What is fuel

  Release energy when combusted - coal and hydrocarbons