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Greenhouse Effect
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Greenhouse Effect Without climate system, Earth much colder than it is
Climate system traps Sun’s energy; distributes heat around world Warming process called ‘Greenhouse Effect’ Recall: UV from sun; IR from ground Greenhouse gases in atmosphere absorb radiation from Earth’s surface and radiate it out in all directions Half of IR radiation sent back to Earth
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Greenhouse Gases Air mostly N and O – don’t absorb radiation
Gases that do absorb IR are called greenhouse gases (mostly H2O and CO2) Also methane (CH4) , ozone (O3) and nitrous oxide (N2O)
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Carbon Dioxide Atmosphere contains 385ppm CO2 (0.0385% of gases)
Estimated to cause up to a quarter of natural greenhouse effect on Earth – volcanoes, burning, cellular respiration of plants and animals
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Carbon Cycle Movement of C through living things
Oceans and living things remove CO2 from atmosphere and store C atoms in different form – called carbon sinks Eg. Plants use CO2 in photosynthesis; ocean sediment is solid calcium carbonate (like in seashells)
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Water Vapour Causes roughly two-thirds of natural greenhouse effect
Quantity depends on temperature – up to 4% Higher temp., more water vapour in atmosphere Relationship called a feedback loop
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Greenhouse Effect How do greenhouse gases trap IR?
N and O are diatomic atoms (2 of same atom); vibrate back and forth Water, carbon dioxide and methane have 3 or more atoms; wiggle in many ways and hit more energy waves
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