When these computations are applied to the parameters of Venus , they show James Hansen's claim that its surface temperature is due to a "runaway greenhouse effect" does not compute .
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Below is a graph showing the calculation of Earth's radiative balance given a few different assumptions . If you have any questions or comments please post them below .
The basics , how to calculate the equilibrium of a gray ball in our orbit
, are at Category:Essential
Physics - ClimateWiki which was a Heartland site . That
provides the basis for How to Calculate
the Temperature of a Radiantly Heated Colored Ball which
culminates in the graph below :
| 20171206.1511 | Replaced http://cosy.com/Science/ScaledSpectra%26hyp.jpg with http://cosy.com/Science/AGWpptHypotheticalSpectra.jpg which includes the assumptions and results of the different hypotheses .
The blue and red curves are the Planck energy , black body , spectra of the sun , scaled to our distance from it , and of a black body in equilibrium with it . The areas under the 2 curves are equal . The temperature generating the red curve is 278.7 kelvin .
The absorptivity of the earth with respect to the sun's spectrum is about 0.7 . There is a line across the sun's spectrum at 7 on the graph . The simple flat , gray , spectrum line is extended in very light blue across the graph .Multiplying by 0.7 or any constant clearly won't change the radiative balance between the blue and red spectra . Thus a gray ball , no matter how dark or light , will come to the same equilibrium temperature . This is the fact ( Kirchhoff-Stewart ) that I learned as a grade school nerd during the Eisenhower administration which has driven my battling this global statist nonscience .
The greenhouse effect can be defined as the difference from this temperature due to the color , ie , spectrum , of an object .
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The Stefan-Boltzmann law is simply that energy density* is proportional to the 4th
power of temperature . Thus , In order to explain our 3% warmer than
gray observed 288 or so temperature , we have to be about 15% less
absorptive , more reflective , in the long wavelengths than our 0.7
with respect to the sun . The green line continues at the ~ 0.6
that works out to . |
For the geeks , the essential relationship computed here it to find temperature T such that dot[ solar ; objSpectrum ] = dot[ Planck[ T ] ; objSpectrum ] where objSpectrum is the absorptivity(=emissivity) spectrum of a object , in this case treating the earth as a uniformly colored ball . dot[ ; ] is the dot or inner product : the sum across the products of the two curves . |
The black line jumping to 10 ( 1.0 ) in the long wavelengths manifests the ubiquitous assertion that
without greenhouse gases , our planet would radiate as a black body .
It produces a temperature of about 255.7 . This number and 33c greenhouse
effect generated by this calculation has grossly retarded any
progress in climate science . The field , both sides , just
career around in their computational clouds somehow trying to make
sense of a quantity which is 2%3 their own creation .
I think it rather obvious that given any particular full spectrum ,
its radiative balance can be calculated . This balance depends on
its spectrum as seen from the outside , not on how it gets there .
Thus it is open to experimental verification as it has been for more
than a century .
It's when when applying these calculations to Venus came up in a
blog exchange things really got interesting . But I'll leave that to
my End
of 2012 NewsLetter .
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