Eddie Banner 29/7/19
As a physicist, I have long had doubts about the Greenhouse Gas Theory for global warming, and I recently came across a post which reinforces these doubts. Although the post itself supports the GHG theory, nevertheless it provides a very interesting diagram, shown below,
which is based upon excellent work by R A Hanel et al with real measurements by satellite taken over the Niger valley in North Africa. It shows the infrared radiative flux emitted to space at the top of the atmosphere.
Fig 1. Satellite measurements
Credit: Data from R. A. Hanel, et al., J. Geophys. Res., 1972, 77, 2829-2841
This diagram gives the results of real, practical observations by the Nimbus satellite, and provides ideas which simply are not forthcoming with the theoretical computer models such as Nasa’s GISS model.
I should like to offer a completely new (as far as I know) treatment, based entirely on these practical results.
The Planck curve for any particular surface temperature of the Earth gives the maximum radiation flux emitted by the surface of the Earth and transmitted to space, assuming the Earth to be a “black body”. Accordingly, the spectrum trace in the diagram would seem to indicate that the radiation emanates from a surface temperature of 320 K. The atmospheric window, through which radiation to space passes largely unimpeded by absorption, is clearly shown between infrared wavelengths of 8 microns and 14 microns.
The figure also demonstrates the absorption of the radiative flux in the 15 micron region by carbon dioxide in the atmosphere.
Working with wavenumbers, because they are a measure of the infrared frequency, and therefore of energy, the wavenumber of a 15 micron photon is 667 cm^-1.
The abscissa is given in terms of cm^-1, which is a measure of frequency, and the ordinate is in terms of milliW.m^-2.(cm^-1)^-1. Therefore, for a 1 second period, the area of any particular portion of the graph has units of the product of abscissa and ordinate.
That is ( milliJoules.m^-2.(cm^-1)^-1) * (cm^-1)
i.e. milliJoules per m^2
So the energy of a part of the graph is given by the area of that part.
The Planck radiation curves are very lengthy to compute without a suitable computer program, so I have printed a copy of the diagram and simply interpolated, and sketched on the print, within the given curves for suitable temperatures.
It is instructive to determine the energies of the various parts of the diagram, and this has been done simply by measuring the areas on the print by pencil and ruler, estimating triangles and parallelograms as appropriate.
The “Planck” temperature values, except for the 320K curve, are not relevant because the radiative flux at all wavenumbers outside the window arises from atmospheric absorption and re-emission, at a lower atmospheric temperature. This is the emission temperature. Since all the radiation emanates from the Earth’s surface, in the absence of absorption the emission curve will follow the shape of the Planck curves. The position of the appropriate curve on the diagram can be found from Fig 4(a) in the paper by W Zhong and J D Haigh (1). This shows that the value of the transmitted radiation at 15 microns, if there were no absorption by CO2, would be 1.42 times the transmittance in the absorbed case. This places the “non-absorbed” position of the trace for 667 cm^-1 at 80 mW.m^-2.(cm^-1)^-1 on the ordinate axis. The corresponding Planck curve without absorption can be sketched in, as above.
At wavenumbers less than about 800, there is clearly absorption by carbon dioxide; this is the area below the ‘sketched” emission temperature curve, between it and the trace of the measured radiation flux.
There is also radiation transmitted to space, shown above the curve at wavenumbers less than 600 cm^-1. So where does this “extra” energy come from? Not directly from the surface because the limit is set by the Planck curve being considered. So it would seem to come from the atmosphere, and this is supported as follows.
Suppose we measure the areas (and therefore the energies) above and also below the emission temperature curve, between 400 and 800 cm^-1. (Several sets of measurements might be made for slightly different emission curves for comparison, if necessary.)
It is found that the two energies are equal, and this suggests that the energy absorbed by the carbon dioxide has been re-emitted to space by photon emission from water molecules below 600 wavenumber.
A temperature is found for which the areas, and therefore the energies, are equal.
Therefore, it appears that, in this case, the emission temperature is about 256, simply using this number to position the curve on the graph.
This emission temperature is readily stabilized. If some perturbation caused this temperature to start to rise, then there would be more energy absorbed by CO2 below 800 cm^-1, and so more feedback to the transmission below 600 cm^-1, which means more cooling by radiation to space. So the emission temperature would fall in response. The converse argument also applies. The system has negative feedback, and so the emission temperature is stabilized.
Now, suppose that the carbon dioxide concentration is doubled. This means that there is more absorption, and so equally more feedback, which means more radiation to space. This means that more carbon dioxide causes more energy to be emitted, so causing a cooling effect.
So, extra carbon dioxide produces more cooling.
Therefore, if there is any increase in atmospheric temperature, it is not due to carbon dioxide.
It follows, therefore, that the GHG theory is NOT valid.