C13: Earth’s Atmosphere Flashcards
Composition of atmosphere ?
80% NITROGEN
20% OXYGEN
CO2
Water vapour
Noble gases
Why are we not certain about earth’s early atmosphere ?
Earth is 4.6 billion yrs old , so lack of evidence
How did 02 appear ?
PHOTOSYNTHESIS
- 6CO2 + 6H2O —> 6O2 + C6H12O6
- green plants release oxygen
- ALGAE increased 02 in atmosphere
How did CO2 reduce ?
FORMATION OF SEDIMENTARY ROCK
- as ocean formed , CO2 dissolved to form soluble carbonate compounds so amount of C02 decreased
- carbonate compounds were PRECIPITATED as sedimentary rock
UPTAKE FROM LIVING ORGANISMS
- CO2 taken from algae and plants when they photosynthesise
- these organisms turn to fossil fuels —> COAL
How did water vapour reduce ?
Water vapour condensed to form oceans after volcanic eruptions
What is the greenhouse effect?
The way in which heat is trapped close to earth’s surface by ‘greenhouse gases’
Importance of greenhouse gases?
- essential to keep planet at good temp for life
- otherwise heat would escape and it would average -20C
How does greenhouse effect work?
EM radiation from sun passes through Earth’s atmosphere
- Earth absorbs some radiation/ warms up . But some heat is radiated from Earth as infrared radiation
- some of the IR radiation is absorbed by greenhouse gases in atmosphere
- atmosphere warms up leading to greenhouse effect
Consequence of raise in greenhouse gases ?
- flooding
- desertification
- melting glaciers
- pollution
Carbon footprint ?
Total amount of greenhouse gases that are generated by our actions
How to reduce carbon footprint ?
- reduce CO2 and methane emissions by:
- using less electricity/ transport
- more trees
- carbon capture
How is SO2 formed, problems and solutions ?
FORMED : sulfur impurities in fuels burn to form SO2
PROBLEMS : acid rain
SOLUTIONS : - use renewable energy
- remove from fuels before burning
- remove from flue gases
N20 how is it formed, problems and solutions?
Formed : oxidation of N2 in high temps in vehicle engines
PROBLEMS : acid rain /asthma
SOLUTIONS :low nitrogen fuels
How are unburned fuels formed , problems and solutions ?
FORMED: release in INCOMPLETE combustion of fuel
PROBLEMS : damage cells/ cancer
SOLUTIONS : check up of engines
How is H20 formed , problems?
FORMED : oxidation of H2 I hydrocarbon fuels
PROBLEMS : amplify water cycle ( more wet/dry regions)