Convection currents are blocked by the glass of greenhouses but not by

Convection currents are blocked by the glass of

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cooling of the planet. Convection currents are blocked by the glass of greenhouses, but not by greenhouse gases. But CO2 does absorb some of the infrared radiation emitted from the planet. Absorbing an infrared photon puts a CO2 molecule into an excited state, and fairly quickly the molecule returns to its unexcited state by emitting a photon of the same energy. Some of those photons emitted by excited CO2 molecules head back towardEarth (the emission direction is random). So, the CO2 serves to trap energy in the Earth system, warming the planet so that it glows more brightly to shove infrared radiation past the CO2, achieving a new balance.Points Earned:1/1Correct Answer:AYour Response:A10.Oxygen (O2) and nitrogen (N2) do not have much greenhouse effect, but several trace gases including carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and various chlorofluorocarbons are important greenhouse gases. The primary mechanismby which these greenhouse gases warm the Earth is:A.Preventing convection currents that take heat aloft, in the same way that the glass of a greenhouse stops convection currents and so makes the air in the greenhouse warmer.B.Raising the atmospheric pressure, because squeezing air warms it, as we saw at
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the Redwoods.C.Making politicians mad, so they give speeches that heat the air.D.Absorbing some of the infrared radiation emitted from the Earth.E.Experiencing chemical reactions with each other, which release energy.Although it is true that squeezing air warms it, the pressure does not set the temperature (change in pressure brings change in temperature), and, the greenhouse gases are really very rare and don’t affect pressure much. The production and breakdown of the greenhouse gases roughly balance energetically, and any slight imbalances are tiny compared to the radiative effects of the gases. Convection currents are blocked by the glass of greenhouses, but not by greenhouse gases. But CO2 does absorb some of the infrared radiation emitted from the planet. Absorbing an infrared photon puts a CO2 molecule into an excited state, and fairly quickly the molecule returns to its unexcited state by emitting a photon of the same energy. Some of those photons emitted by excited CO2 molecules head back toward Earth (the emission direction is random). So, the CO2 serves to trap energy in the Earth system, warming the planet so that it glows more brightly to shove infrared radiation past the CO2, achieving a new balance.Points Earned:1/1Correct Answer:DYour Response:D
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  • Fall '08
  • ALLEY,RICHARDBANANDAKRISHNAN,SR
  • Global Warming, CO2, Correct Answer, Greenhouse gas, Coal

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