unit 2 - climate change

• What does the atmosphere consist of?

  A mixture of solids, liquids, and gases
• What are the main gases found in the atmosphere up to a height of around 80 km?

  Nitrogen, oxygen, argon, and trace gases like carbon dioxide, helium, and ozone
• Where does most weather occur in the atmosphere?

  In the troposphere
• How does temperature change with height in the troposphere?

  Temperatures fall with height at an average rate of 6.5°C per km
• How much water vapor is contained in the lowest 15 km of the atmosphere?

  Most of the water vapor is contained in the lowest 15 km
• What happens to the atmosphere above 15 km in terms of water vapor?

  The atmosphere is too cold to hold water vapor
• At what altitudes are significant concentrations of ozone found?

  Between 25 km and 35 km
• What is insolation?

  Incoming solar radiation
• How does solar energy affect weather systems and climates?

  Solar energy drives all weather systems and climates
• Where does the Earth absorb most solar energy?

  In the tropical regions
• What compensates for the loss of energy from temperate and polar regions?

  Redistribution of energy from lower latitudes to higher latitudes
• What is the atmospheric energy balance?

  The balance between inputs (insolation) and outputs (re-radiation)
• What recent phenomenon has disrupted the atmospheric energy balance?

  Global warming linked with human activities
• What are the three main ways the balance is achieved under natural conditions?

  Radiation, convection, and conduction
• What type of radiation does the Sun primarily emit?

  Short wavelengths such as ultraviolet and visible light
• How is heat transferred by conduction?

  By contact between substances
• What is latent heat transfer?

  Heat energy used by a substance to change form without changing temperature
• How much short-wave radiation is re-radiated as long-wave radiation?

  14 units
• How much solar energy is absorbed by the Earth?

  46%
• What percentage of solar energy drives the hydrological cycle?

  22%
• What is the greenhouse effect?

  The process by which greenhouse gases trap outgoing long-wave radiation
• Why is the greenhouse effect important for life on Earth?

  It raises temperatures to levels suitable for life
• What is the most common greenhouse gas?

  Water vapor
• How have carbon dioxide levels changed from 1950 to 2015?

  Increased from about 315 ppm to over 400 ppm
• What human activities contribute to the rise in carbon dioxide levels?

  Burning fossil fuels and land-use changes like deforestation
• What is the impact of deforestation on carbon dioxide levels?

  It increases atmospheric CO2 levels and reduces carbon storage
• What is the second-largest contributor to global warming?

  Methane
• How much methane do cattle emit annually?

  100 million tonnes
• What are chlorofluorocarbons (CFCs) known for?

  Destroying ozone and absorbing long-wave radiation
• How much more efficient are CFCs at trapping heat compared to CO2?

  Up to 10,000 times more efficient
• What are Milankovitch cycles?

  Variations in the Earth's orbit affecting solar radiation distribution
• How do changes in albedo affect global temperatures?

  As ice melts and is replaced by darker vegetation, more insolation is absorbed, raising temperatures
• What is global dimming?

  The cooling of air temperature due to pollution
• How did the 9/11 terrorist attacks affect average temperatures?

  Average temperature rose by about 1.1°C due to the absence of contrails
• What happens to solar energy reaching the Earth's surface due to pollution?

  Polluted clouds reflect more sunlight back into space, preventing some insolation from reaching the surface
• How do sulphate aerosols affect solar radiation?

  They scatter incoming solar radiation back to space
• What is the albedo value of fresh snow?

  75–90%
• How does the albedo of coniferous forests compare to that of fresh snow?

  Coniferous forests have an albedo of 5–15%, much lower than fresh snow
• What role do feedback mechanisms play in the Earth's atmosphere?

  They control changes in global warming
• What are the two types of feedback loops associated with climate change?

  Positive and negative feedback loops