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ATMS 749 Atmospheric Radiation Transfer. Electromagnetic Waves … demonstration. Slinky illustrates longitudinal and transverse waves. Polarization cards illustrate Brewster angle reflection from floor tiles with ‘natural light’ incident. CHAPTER 1 EMISSION: Birth of Photons.
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Electromagnetic Waves … demonstration Slinky illustrates longitudinal and transverse waves. Polarization cards illustrate Brewster angle reflection from floor tiles with ‘natural light’ incident.
CHAPTER 1EMISSION: Birth of Photons Wave/Photon boson: Polarization. Linear Polarization: E-field in one direction. Circular, elliptical polarization: E-Efield rotates due to phase difference between horizontal and vertical components. From: http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/polclas.html
More Details on the Polarization States Elliptical Polarization: The most general representation. Circular Polarization
The Big Picture, On Average OLR is balanced by ASR. More flux at the equator and less at the poles drives atmospheric circulations as the planet responds with atmospheric and oceanic circulatiouns, like a heat engine, to relieve the asymmetry. Why do OLR and ASR have the values shown?
Energy Transfer From Equator to Poles Radiant energy per year ---> Fig. 9.2
The Big Picture, On Average Energy pathways are available to the Earth to relieve the ‘burden’ of solar energy. Is it valid to state that the Earth converts solar radiation to IR? How much of the IR emitted by the surface is directly emitted to space? Where is most of the solar radiation absorbed? Do the numbers add up for a radiation balance at the top of the atmosphere? What roles do conduction, latent heat, and rising air (convection) play in the energy balance?
The Big Picture, On Average IR Solar How would the numbers change if ‘cloudiness’ increased? Which numbers change as we increase the CO2 concentration? heat
The Big Picture, Atmospheric radiation drives the global circulation, both in the atmosphere and in the ocean.
Satellite Images Geostationary Satellite Images example of visible, IR, and water vapor satellite images.
Atmosphere and Ocean Infrared From: http://www.sonoma.edu/users/f/freidel/global/. What’s missing?
Three Choices for Radiation Emissivity is the same as absorptivity. Source can be visible or infrared radiation, or other wavelengths as well. Climate consequences of these choices…. (from www.ldeo.columbia.edu/.../solar_radiation)
Earth’s Surface Temperature Te Earth’s radiative temperature Ts Sun’s radiative temperature Rs Sun’s radius Rse Sun to Earth distancea Earth’s surface solar reflectancet IR transmittance of Earth’s atmosphere.
Simple Surface Temperature Calculation Assuming Solar Absorption only at the surface, IR emission by the atmosphere and Earth’s surface, and IR absorption by the Atmosphere. S0 = 1376 W/m2=Solar Irradiance at the TOA and =Stefan-Boltzmann constant
Greenhouse Effect: from http://www.dnrec.delaware.gov/ClimateChange/Pages/Greenhouse%20Effect.aspx
Greenhouse Effect: from http://www.dnrec.delaware.gov/ClimateChange/Pages/Greenhouse%20Effect.aspx
Spectrum of Solar Radiation Flux • The sun emits 41% of its radiation in the visible spectrum, • 9% in the ultraviolet spectrum • 50% in the near infrared spectrum
Earth Light: Spectrum of Outgoing Infrared Radiation From http://www.lib.utah.edu/services/prog/gould/1998/Figure_5.gif
Infrared Spectrum from the Atmosphere to the Surface CO2 H20 O3 CH4
Spectrum of Solar Radiation Flux • O3 • O2 • H2O • H2O • ,CO2 .1 . 3 .5 1 1.5 2 2.5 3 From Cunningham & Cunningham, 2004,
Global Energy Balance Incoming = 45 +88 = 133 Outgoing = 104 + 24 + 5 = 133 From Cunningham & Cunningham, 2004, Fig. 9.2