1. I didn't see any glaring errors in your Venus absorbtion caluculation of ~80w/m^2.. Have you seen the Pioneer Venus probe data that showed about 200 w/m^2 was getting through the cloud shroud with about 20 w/m^2 getting to the surface? That would seem to imply we are missing 100 w/m^2 somewhere.
Have you seen the Pioneer Venus probe data that showed about 200 w/m^2 was getting through the cloud shroud with about 20 w/m^2 getting to the surface?
No my calculation are essential taking the NASA data on albedo and blackbody temp as stated in http://nssdc.gsfc.nasa.gov/planetary/factsheet/venusfact.html, for Venus.
The blackbody temp is a function of bond albedo 75% of incident solar flux at Venus orbit reflected before it can get into the atmosphere or the surface to be absorbed and re-emitted as IR to be trapped or absorbed by whatever.
What I have done is calculate a theoretical blackbody calc for change in temperature of a psuedo-mirror above Venus, that reflects solar only at 75%, and transmits 100% venus blackbody IR so we remove the effect of the sulfuric acid cloud layer on surface temperature, but do reduce the solar flux to that which is implied by the listed albedo. The idea being, to isolate that effect that due to a CO2 atmosphere absent all other factors.
The CO2 abosorption is set by the spectrographic absorption qualities of CO2, by the MODTRAN & the Myhre relationship as the MODTRAN program isn't designed to handle 92 bar 96% CO2 atmosphere so I had to make use of both to get where we wanted to be.
What was calculated is a purely theorectical number based on the listed blackbody temp as starting point and a 96.2% CO2, 92 bar atmosphere to establish what the contribution of CO2 to the Venus temperature must be.
An alternative route would be to assume a pure blackbody at 231.7K with a 100% IR absorbing gas in the atmosphere.
The calculation would that be for an absorption of all 163.41 w/m2 instead of the 80 we established for CO2, for which we must compensate by raising temperature to a full:
(163.41*2)/(5.67*10-8)]0.25 = 275.53K
With a delta T of (275.53-231.7) = 43.3oC, still a very long way from the conditions actually found at the surface.
Either way, it becomes clear that the conditions on Venus are not due to IR absorption of the atmosphere alone, however efficient it might be at such.
Rather the temperature conditions on Venus surface must be explained in some other mechanism such as cloud scattering and reflection of IR back to the surface in much the same way that a one way mirror would work which brings us back to the applicablility of the conjecture in comment #31, of R. T. Pierrehumbert and C. Erlick (1998):
AMS Online Journals - On the Scattering Greenhouse Effect of CO2 Ice Clouds Consider an atmosphere-clad planet with net albedo a0 in the solar spectrum. If it is illuminated by a solar flux, S0, and radiates infrared to space at a rate, I0, it is in equilibrium when (1 - a0)S0 = I0. Now introduce a high CO2 ice cloud with albedo ac in the visible and a'c in the infrared, but that absorbs neither solar nor infrared radiation. This perturbs both the solar and infrared terms in the radiation budget, as shown in Fig. 1 . Let the cloud be high enough that it is above virtually all of the infrared-radiating mass of the atmosphere and suppose that the subcloud atmosphere–surface system is a perfect infrared absorber. Taking into account the effects of multiple scattering between the high cloud and the subcloud regions, the cloud changes the planetary solar albedo to
a = ac + a0 [(1 - ac)2/(1 - aca0)]. (1)
If I1 is the upward infrared flux from the subcloud atmosphere, the flux escaping to space is (1 - a'c)I1. To restore equilibrium with the insolation S0, the temperature must change so as to make I1 = [(1 - a)/(1 - a'c)]S0.
The I1 required to balance the absorbed solar radiation becomes infinite if a'c ® 1 with a < 1, in which case the planetary temperature also becomes infinite. In this limit, the cloud acts like a one-way mirror that lets solar radiation in but does not let any planetary radiation out. This state of affairs would violate the second law of thermodynamics, as the planetary temperature would exceed the solar blackbody temperature. In fact, the temperature limits itself because, once the surface warms to solar temperatures, it radiates at solar wavelengths and the albedo for solar and planetary radiation becomes identical. This limit nevertheless shows the potency of the cloud-mirror effect. In contrast, the conventional greenhouse effect for a single-layer IR-absorbing cloud could increase the unperturbed temperature by no more than a factor of 21/4. Unlike the conventional greenhouse effect, the scattering greenhouse effect blocks IR emission to space without the clouds having to absorb any IR themselves. The clouds therefore do not have to heat up in response to the absorbed radiation, which removes a limit to warming inherent in the conventional single-layer case.
2. Have you seen either the ~80w/m^2 absorption number or the 25 degree contribution to warming from CO2 anywhere reputable other than that 1994 paper or its 2002 electronic version?
No, and why would it matter?
The radiative absorption characteristics of CO2 are well known, the blackbody calcs are standard thermodynamics and as we have applied it assumes the maximum efficiency possible for an asbsorption situation. The results are what they are and one is required to look beyond the capacity of CO2 to absorb IR radiation to explain why Venus' surface is as hot as it is.
Just as one must look beyond CO2 alone as to explain all that happens in earth's atmosphere as regards climate here.
>>Just as one must look beyond CO2 alone as to explain all that happens in earth's atmosphere as regards climate here.<<
I'll come back to the rest but I hope you don't think we have a disagreement on this point.