Tag: radiation

Water Vapor is by far the most significant Green House Gas (GHG)

ghgabsoprtionspectrum

The only defined mechanism by which CO2 can affect climate change is by affecting outgoing radiation between the wavelengths of 13 and 18 microns.

  1. Incoming visible radiation has a wavelength between 0.4 and 0.7 microns, and is consistent with a black body of temperature of around 5,200 degree C (the Sun). CO2 is transparent to these wavelengths.
  2. The earth emits IR mostly between 6.5 and 12.5 microns, with a peak near 9.5 microns. 9.5 microns is consistent with a black body of temperature  18 degrees Celsius. CO2 is mostly transparent to those wavelengths.
  3. CO2’s absorbs between 13 and 18 microns, with a peak near 15 microns. Those wavelengths are consistent with a black body of temperature -80 degrees Celsius.
  4. H2O is by far the most significant GHG, and absorbs across the IR Spectrum.
  5. CO2 absorbs a small fraction of the IR Spectrum having 3 narrow peaks at 2.7, 4.3 and 15 microns, all of which largely miss the peak outgoing  IR radiance of the earth at 9.5 microns.
  6. H2O largely absorbs the same IR spectrum as CO2, and is at much higher concentrations in the atmosphere. H2O IR absorption makes CO2 contribution to warming inconsequential.