Download SOAR: The Science behind Solar Radiation, Greenhouse Gases

SOAR: The Science behind
Solar Radiation, Greenhouse
Gases, and Greenhouse Effect
Suresh Dhaniyala, Mechanical and Aeronautical Engineering
Clarkson University, Potsdam, NY
315 268 6574; [email protected]
Outline
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Agenda
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Introduction
Electromagnetic (EM) spectrum
Blackbody radiation
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Greenhouse gases (GHGs)
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EM emission spectrum of Sun, Earth lightbulb etc.
Absorption of EM radiation
GHG concentration and temperature
All applets will be accessed from:
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Google “Clarkson K-12” (http://www.clarkson.edu/highschool/k12/)
Click on
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Climate change education
Project-based climate modules
Greenhouse effect
Current state of the climate
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Current state of the climate (NOAA)
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http://www.climate.gov/#climateWatch
How globally-averaged temperatures have
changed over the past decade
Change in atmospheric CO2
concentrations over the past 50 years
Climate change
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Documented increase in globally-averaged temperatures
over the past 40 year or so
Temperature increase has corresponded to increase in
CO2 concentrations
Questions:
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Why is the temperature rising?
What is the connection with CO2 concentrations?
Need to understand:
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Greenhouse effect
Greenhouse gases
Solar radiation and Terrestrial radiation
Electromagnetic radiation
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How do cell phones communicate with towers?
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Radiofrequency waves
Radiofrequency waves
In the spectrum of Electromagnetic waves
Source: Planet Adirondack, The Wild Center;
Electromagnetic (EM) radiation
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Examples of other kinds of EM radiation?
Used for cooking in your kitchen
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Microwaves
Night-time imaging
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Infrared
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Light, x-rays, gamma rays
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What’s common?
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They are all part of the Electromagnetic Spectrum.
Credit: NASA/JPL-Caltech/R. Hurt (SSC)
Electromagnetic radiation
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EM radiation - background
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http://imagine.gsfc.nasa.gov/docs/science/k
now_l1/emspectrum.html
EM radiation – applets
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Under “Resources” - Click on
“Electromagnetic Spectrum Applet”
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(http://lectureonline.cl.msu.edu/~mmp/a
pplist/Spectrum/s.htm)
Investigate:
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What wavelengths correspond to:
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Visible light
Heat radiation
Solar and Terrestrial radiation
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All bodies emit electromagnetic radiation
Most of the energy is emitted in one form of Electromagnetic
(EM) radiation
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The nature of emission depends on the body temperature.
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e.g., light, IR, etc
Hotter bodies emit shorter wavelengths.
Applet – Click on “Blackbody radiation applet”
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Investigate: What are the peak wavelengths of EM radiation
corresponding to:
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Sun (~ 10,000 F)
Earth (~ 70 F)
Incandescent light bulb
Applet Source: PhET, University of Colorado. http://phet.colorado.edu/en/simulation/blackbody-spectrum
Note: Flash required to run this program (http://get.adobe.com/flashplayer/ )
Emission profiles
Sun
(5777K)
Earth
(300K)
Earth’s Energy Balance
Solar radiation
Terrestrial radiation
Source: http://earthobservatory.nasa.gov/Features/EnergyBalance/
Greenhouse effect
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Energy radiated from Earth is trapped, but energy from Sun
is allowed through
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Helps keep Earth’s temperature warm enough for humans to
survive
Applet
 Click on “Greenhouse effect simulation”
 In the applet, click on “Glass layers” tab
Investigate:
 What is Earth’s temperature in the absence of any “glass
layer”
 How does the temperature change as you add “glass
layers”
Applet Source: PhET, University of Colorado. http://phet.colorado.edu/en/simulation/greenhouse
Note: Need Java to run this program
Greenhouse gases
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Certain gases in the atmosphere can act as “glass layers”
and absorb the out-going long-wave radiation
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Applet
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These gases are referred to as greenhouse gases (GHGs)
Click on “Greenhouse effect simulation”
In the applet, click on “Photon Absorption” tab
Investigate:
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Which gases are greenhouse gases?
Applet Source: PhET, University of Colorado. http://phet.colorado.edu/en/simulation/greenhouse
Note: Need Java to run this program
Greenhouse Gases and Earth’s Temperature
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The concentration of greenhouse gases in the atmosphere
determines Earth’s temperature
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Applet
 Click on “Greenhouse effect simulation”
 In the applet, click on “Greenhouse effect” tab
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Investigate:
 What is Earth’s temperature with no greenhouse gases?
 What is Earth’s temperature considering the greenhouse
gases during:
 Ice-age, pre-industrial
era (1750) and today?
Applet Source: PhET, University of Colorado. http://phet.colorado.edu/en/simulation/greenhouse
Note: Need Java to run this program
Radiation spectra
Source: Wikipedia
Future trends
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The future emissions of greenhouse gases depends on
our lifestyle and societal developments
We can imagine scenarios and model (i.e., calculate) what
the future climate might look like
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IPCC models different “scenarios”.
All models suggest much warmer climates
Upcoming SOAR Classes:
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Susan Powers – “Sources of Greenhouse Gases and Your Own
Carbon Footprint. (3/25; CAMP 163)
Jon Rosales – “On the Front Lines.” (4/01; CAMP 175)
Stephen Bird – “Integrating Science into the Policy
Process.” (4/08; CAMP 175)
Applets
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All Applets can be accessed from
http://www.clarkson.edu/highschool/k12/
Other References:
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IPCC report, 2007
Hardy J.T., Climate change: Causes, Effects, and Solutions, Wiley
Publications, 2006
www.earthobservatory.nasa.gov
NOAA : www.climate.gov