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Topics for Today. Climate Change: A Global Problem? Quiz #7 (of 11)!!. Readings for Today. May even bleed into Monday. 3.8 Methane and other greenhouse gases 3.10 Responding to science with policy changes 3.11 The Kyoto Protocol on Climate Change
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Topics for Today • Climate Change: A Global Problem? • Quiz #7 (of 11)!!
Readings for Today May even bleed into Monday. • 3.8 Methane and other greenhouse gases • 3.10 Responding to science with policy changes • 3.11 The Kyoto Protocol on Climate Change • 3.12 Global warming and ozone depletion
Topics for Monday • Where does the Carbon Go? • The Carbon Cycle http://www.esd.ornl.gov/iab/iab2-2.htm
Readings for Monday • 3.5 The Carbon Cycle
Announcements! Nice, warm weather… Please remember: Do not wear shorts or sandals to lab!!
Topics for Today • Climate Change: A Global Problem? • Quiz #7 (of 11)!!
Review… The Greenhouse Effect
Q: When will IR cause a molecule to vibrate? A: When there is a dipole moment!
Review Dipole Moment: Unequal distribution of charge! N2?? Does CO2 absorb IR radiation?
DEMO!! CO2 N2
What makes greenhouse gases more potent? N2O HCFCs CH4 CH4 CFCs O3 HFCs CO2 H2O
3) How efficiently can the molecule absorb IR? 1) Atmospheric Lifetime 2) Atmospheric Concentration
3) How efficiently can the molecule absorb IR? 1) Atmospheric Lifetime 2) Atmospheric Concentration
CO2 bending and stretching… CO2 has only 3 vibrations • Summary • Symmetric Stretch • Asymmetric Stretch • Bend 1 • Bend 2
This is due to the more complicated SHAPE CFCs CFCs have at least 10 possible vibrations!! CFCs are much more efficient at trapping IR than CO2.
3) How efficiently can the molecule absorb IR? 1) Atmospheric Lifetime 2) Atmospheric Concentration 4) WHERE it absorbs in the IR range!!
Figure 3.16 Water Vapor
CO2 Figure 3.15 in your Text
What about the other gases? CO2 Figure 3.15 in your Text
This range is called the “atmospheric window.” Very little IR is absorbed from 8-12 micrometers!! Reminder: This is 8,000-12,000 nm!!
Micrometers? HCFC 132a www.sstd.rl.ac.uk/srg/srgproj/ircfc/ircfc.htm
HCFC 132a CFCs (and replacements) absorb directly in the atmospheric window!!! 17 10 7 5 2.8 MICROMETERS www.sstd.rl.ac.uk/srg/srgproj/ircfc/ircfc.htm
Where do CFCs absorb? At about 7-11 micrometers!!
3) How efficiently can the molecule absorb IR? 1) Atmospheric Lifetime So, just how potent are the major GHGs? 2) Atmospheric Concentration 4) WHERE it absorbs in the IR range!!
Global Warming Potential (GWP) • The ability for a gas to trap energy in the atmosphere. Based on an equal mass of CO2 over a specific time period. http://www.ace.mmu.ac.uk/eae/Global_Warming/Older/GWPs.html
GHGs are not the only thing in the atmosphere that change the Earth’s energy balance!!!
Global Warming Potential (GWP) • The ability for a gas to trap energy in the atmosphere. Based on an equal mass of CO2 over a specific time period. http://www.ace.mmu.ac.uk/eae/Global_Warming/Older/GWPs.html
Greenhouse gases correlate with warming! CO2 Concentration (ppm) TEMPERATURE CHANGE
Venus’ atmosphere is about 97% CO2 Runaway greenhouse effect! The average temperature is about 900oF! http://hyperphysics.phy-astr.gsu.edu/hbase/solar/venusenv.html
Very thin atmosphere; most of the CO2 is frozen in the ground… The average temperature is about -60oF!
CO2 Concentration (ppm) TEMPERATURE CHANGE
So what if the Earth gets a little warmer?? This is an average…
Greenhouse gases lead to more energy trapped in the atmosphere.
Overall, the Earth’s natural energy balance is changed The effects of this can can vary…