1- The Atmosphere
Terms in this set (40)
Nitrogen: 78%
Oxygen: 21%
Composition of our atmosphere
Argon: 0.9%
Carbon dioxide: 0.04%
Composition of our earliest atmosphere Hydrogen, Helium
How did our earliest atmosphere go? gases so light they go to space
CO2, ammonia, methane, water vapour
Composition of our early atmosphere
No oxygen, nitrogen
How did our early atmosphere form? Volcanic eruptions (gases expelled are normally CO2 and water vapour)
How did our oceans form? Earth cooled, water vapour condensed, rain
- dissolved in water (oceans)
- reacts with calcium to produce limestone/chalk
How did CO2 levels decrease?
- photosynthesis
- fossil fuels (marine, plants)
How did O2 levels increase? - photosynthesis
How did ammonia levels decrease? ammonia + oxygen = nitrogen + water
How did nitrogen levels increase? ammonia decomposed on reaction with oxygen
How did methane levels decrease? methane + oxygen = carbon dioxide + water
What are greenhouses gases? gases that contribute to the greenhouse effect
Examples of greenhouse gases carbon dioxide, methane, water vapour, CFCs, nitrous oxide
Why do we need the greenhouse effect? keeps Earth warm to support life
Short wavelength (UV) radiation passes through the atmosphere to warm the earth,
How does the greenhouse effect work? long wavelength (Infrared) radiation is absorbed by greenhouse gases and
reemitted or lost, this increases atmospheric temperature
What is global warming? an enhanced greenhouse effect
extra GHGs released by human activity are trapping more Infrared radiation
Why is there global warming?
causing gradual temperature increase
sunspot activity (natural cycle as Earth has been through periods of varying
Suggested theory of global warming (incorrect)
climate)