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Language of the Energy Cycle: The Electromagnetic Spectrum

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Presentation on theme: "Language of the Energy Cycle: The Electromagnetic Spectrum"— Presentation transcript:

1 Language of the Energy Cycle: The Electromagnetic Spectrum
Wavelength l Speed of light = wavelength (l) x frequency = 3 x 108 m/s in vacuum Wavenumber = 1/ wavelength ( cm-1) Frequency in GHz (1 Hz = sec –1)

2 1. Power Source: Blackbody Radiation
Planck’s Law: The amount and spectrum of radiation emitted by a blackbody is uniquely determined by its temperature Max Planck (1858 – 1947) Nobel Prize 1918 620 K 380 K Emission from warm bodies peak at short wavelengths wavelength

3 Solar Spectrum = Shortwave spectrum =visible spectrum:
Sun at 6000K; peak emission at 0.5 mm

4 Terrestrial Spectrum = Longwave Spectrum = Infrared Spectrum = Thermal Spectrum: Sahara Desert on Nimbus 4 Satellite CO2 H2O O3 Theoretical Planck curves: Earth ~300K, peak emission ~15 mm

5 Electromagnetic Spectrum
Sun Earth High energy Short wavelength / high frequency Emitted at high T

6 Vibrational Modes for CO2
2. What happens to the radiation in the atm? Vibrational Modes for CO2 C O n1 symmetric n bending 15 mm n2 asymmetric 4.3 mm Greenhouse effect: Radiation at specific wavelengths excite CO2 into higher energy states: energy is “absorbed” by the CO2 molecules

7 Other Greenhouse Gases
water ozone N O C H methane Nitrous oxide

8 Atmosphere: Characteristic Absorption/Transmission for different atm molecules for l: 0-15 µm

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10 Earth Spectrum Incoming from Sun: High energy, short wavelength
0.5 mm Outgoing from Earth Low energy Long wavelength 20 mm 10 mm

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14 Earth’s Energy Balance
50 CO2, H2O, GHG 100 Shortwave Longwave


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