C13 - the earth's atmosphere

• What is one theory about how the Earth's atmosphere developed?

  Volcanoes released gases forming the atmosphere
• How do scientists reconstruct the early atmosphere of Earth?

  By studying gas bubbles in ancient rocks
• What gases did volcanoes release to form the early atmosphere?

  Carbon dioxide, water vapour, and nitrogen
• What happened to water vapour as the Earth cooled?

  It condensed and fell as rain
• What are two theories about the source of water on early Earth?

  Volcanic release and comet impacts
• Which planets have atmospheres similar to early Earth?

  Mars and Venus
• What was the composition of the early atmosphere likely to be?

  Mainly carbon dioxide with little oxygen
• When did life first appear on Earth?

  About 3.4 billion years ago
• How did algae contribute to the atmosphere?

  They produced oxygen through photosynthesis
• What was the significance of rising oxygen levels in Earth's history?

  It allowed more complex life forms to evolve
• What is the chemical formula for methane?


  CH₄
• What is the chemical formula for ammonia?


  NH₃
• How did carbon dioxide get removed from the early atmosphere?

  By dissolving in ocean water and forming rocks
• What is the current percentage of nitrogen in the atmosphere?

  78%
• What is the current percentage of oxygen in the atmosphere?

  21%
• What is the current percentage of argon in the atmosphere?

  0.9%
• What is the current percentage of carbon dioxide in the atmosphere?

  0.04%
• What is the greenhouse effect?

  Gases absorb energy and warm the Earth
• What happens to energy from the Sun when it reaches Earth?

  Some is reflected, some is absorbed
• How do greenhouse gases affect Earth's temperature?

  They trap infrared radiation from the surface
• What has caused the increase in carbon dioxide levels recently?

  Burning fossil fuels for energy
• What is the chemical equation for the combustion of propane?

  C₃H₈ + 5O₂ → 3CO₂ + 4H₂O
• What are two sources of methane emissions?

  Swamps and cattle waste
• Why is nitrogen gas able to build up in the atmosphere?

  Because it is very unreactive
• What are the main greenhouse gases in the Earth's atmosphere?

  • Carbon dioxide (CO₂)
  • Methane (CH₄)
  • Water vapour (H₂O)
• What are the main changes in the atmosphere over time?

  • Increase in oxygen levels due to photosynthesis
  • Stabilization of gas proportions
  • Formation of fossil fuels from ancient organisms
• How does photosynthesis contribute to the atmosphere?

  • Plants absorb carbon dioxide
  • Produce glucose and oxygen as byproducts
  • Increase oxygen levels in the atmosphere
• What is the significance of peer review in scientific research?

  • Validates research findings
  • Ensures accuracy and reliability
  • Helps communicate results effectively
• What are the potential biases in media reports about climate change?

  • Oversimplification of complex issues
  • Sensational headlines without context
  • Lack of comprehensive scientific data
• What type of radiation does the Earth emit to cool down?

  Infrared (thermal) radiation
• How do greenhouse gases affect temperature?

  They absorb infrared radiation, raising temperature
• What happens to energy radiated from the Earth's surface?

  Some energy gets trapped in the atmosphere
• What has caused the increase in carbon dioxide levels?

  Burning fossil fuels
• What is released when fossil fuels are burned?

  Carbon dioxide and water
• What is the balanced equation for burning propane?

  $C_3H_8 +$$5O_2 \rightarrow 3CO_2 +$$4H_2O$
• Where does methane come from?

  Swamps, rice fields, and cattle emissions
• Why are greenhouse gas levels increasing?

  Due to human activities and population growth
• What is the enhanced greenhouse effect?

  Increased warming due to higher greenhouse gases
• What evidence do scientists use to study climate change?

  Ice cores from Greenland's ice sheet
• What do ice cores reveal about carbon dioxide levels?

  Current levels are higher than in 440,000 years