Global warming is not caused by CO2

[vanesch]

N If you wish to equilibrate two black bodies originally at the same, higher temperature than CMB with intergalactic space, the rate of cooling can be reduced by whatever fraction of 4 pi steradians each subtends of the other's exposure to the CMB background temperature bath.

Yes, I guess that was what Andrew was after.

You keep taking the first step of the random walk Gamow treats in very simplified fashion for energy transport from the center of the sun to the solar surface; take the rest of the trip --- a "photon" (or the equivalent energy) proceeds by "the drunkard's walk" from the center of the sun to its surface in a time of the order of thousands of years, and you may conclude that infrared proceeds from Earth's surface to space by the same "drunkard's walk," and if you do the calculation you'll find an order of magnitude for "residence time" for this "excess greenhouse energy."

Indeed. That's the "radiation resistance" you have there: the radiative transfer, layer by layer, of heat energy in the form of photons, converted into molecular motion/excitation/..., and again into photons etc...
The point I tried to make was that having solely radiative heat transport will require a higher source surface temperature, than if you add convection next to the radiative transfer, because convection will transport part of the heat (and hence diminish the required heat flux by radiative transport). This comes down to saying that convection is an extra heat transport mechanism which will give rise to a lower rise in surface temperature as compared to when there would be no convection. However, I admit not having any idea by how much, but I'm pretty sure about the *sign* of the contribution (namely, negative).

 

[Andrew Mason]

NO! NO! NO!

Kirchoff's Law! Review it! Understand it! The third blackbody you introduce in this statement (vacuum --- without a temperature specification) is the temperature bath with which your two black bodies are in equilibrium.

In my example, the two blackbodies are not in thermal equilibrium with a third blackbody. Since their temperatures are constant, the rate of energy input is equal to the rate of energy output. There has to be input energy from some energy source for this to occur, but that need not be a third blackbody.

We assume that Earth is in thermal equilibrium ie. its temperature does not change. This is not true over a short period of time, but it is generally true over a long period of time. All this means is that the rate of energy input equals the rate of energy output. We will ignore the energy input that is stored in the Earth in a form other than heat, so energy output is deemed to be all in the form of radiation into space. Energy input is from various sources: sun, moon, stars, CMB, cosmic rays, Earth's internal core.

There is no net exchange of energy among the three, and no temperature change.

I don't understand what you are saying. What are the three bodies? One cannot be in thermal equilibrium with space. Space, by definition, is devoid of matter so it cannot have a temperature. The rate of outradiation of the blackbody is greater than the incoming CMB radiation. .

If you wish to equilibrate two black bodies originally at the same, higher temperature than CMB with intergalactic space, the rate of cooling can be reduced by whatever fraction of 4 pi steradians each subtends of the other's exposure to the CMB background temperature bath.

You keep taking the first step of the random walk Gamow treats in very simplified fashion for energy transport from the center of the sun to the solar surface; take the rest of the trip --- a "photon" (or the equivalent energy) proceeds by "the drunkard's walk" from the center of the sun to its surface in a time of the order of thousands of years, and you may conclude that infrared proceeds from Earth's surface to space by the same "drunkard's walk," and if you do the calculation you'll find an order of magnitude for "residence time" for this "excess greenhouse energy."

We aren't concerned with the residence time of photons in the sun. We are only concerned with its energy output. Since the temperature of the sun is fairly constant we conclude that the energy input (from fusion in its core) is equal to its energy output.

AM

 

[DEMcMillan]

Originally posted by Bystander:

This silly thread has been going on and on and around and around in circles. Results of transmission measurements discussed independently of emissivities aren't going to get anyone anywhere --- let's all do all the applicable physics together at one time, just once, shall we?

This thread has covered a lot of ground and is now able to consider its title. I will put forward an estimate of the scale of the CO₂ contribution for others to consider and increase or reduce in scale, based upon Bystander’s emissivity theme. I estimate that the effect of the 14% CO₂ rise over the last 30 years is 0.05 + 0.01 ^oC. I submit that the use of HITRAN CO₂ data requires information about local difference in upward and downward longwave flux for its implementation. The line by line models being used, including Modtran, use a balancing system of optical depth and spectrum-wide compensating gray scale to estimate photon scattering back to the surface. The atmosphere radiates on the basis of its temperature, like all other matter. I have pointed out elsewhere that analytical chemistry of stratosphere gases utilizes a program that requires emissivity estimation and “black body” or 1.0 is used. https://www.physicsforums.com/showthread.php?t=261966 . The upper stratosphere (50km, 1mPa) is much warmer than any tropospheric area above 6 km altitude. Therefore it should contribute more to downward longwave radiation than anything but clouds and ground-related inversions (see Andre’s graph on the above thread). Interest in cloud effects has generated measurements of downward longwave radiation. Antarctic data from NCEP/NCAR revisions in figure 2b of http://psc.apl.washington.edu/zhang/Pubs/Zhang_Antarctic_20-11-2515.pdf shows the average was 223 W/m2, a value clearly higher than the outward radiation level of the Antarctic continent. This means that all greenhouse gases will lower temperature by scattering IR photons into space. I added a review of Hansen’s CO₂ doubling estimates and a 69% lowering of his numbers by 50 km earthward radiation equal in emissivity to the surface and now use a nonlinear 14% to lower his current estimate to 0.05 ^oC. I recall an Antarctic IR spectrum showing a positive 13-18 μ peak to support my model but can’t find it. Can anyone help?

 

[Bystander]

(snip)I estimate that the effect of the 14% CO₂ rise over the last 30 years is 0.05 + 0.01 ^oC. I submit that the use of HITRAN CO₂ data requires information about local difference in upward and downward longwave flux for its implementation. The line by line models being used, including Modtran, use a balancing system of optical depth and spectrum-wide compensating gray scale to estimate photon scattering back to the surface.(snip)

Like that --- yeah. And from "scattering back to the surface" it's easy enough to segue back to "random walk/drunkard's walk." The hope was that someone was going to apply Gamow's random walk treatment to the Earth's atmosphere (pick a total path length, mean free path per step) and come up with a "residence time" for energy "trapped" by CO₂ IR bands, multiply that time by the surface radiation flux, divide by atmospheric heat capacity, and come up with an upper limit for the "radiative greenhouse" effect. No such luck --- it's on the order of seconds (single digit seconds --- to maybe 10s if we throw in relaxation times), and is measured in mK at the bottom line. Compare that time to the week, 10 days, 2 weeks implicit in the 30 K "atmospheric greenhouse" we're seeking, and recall the "week, 10 days, 2 weeks" time scales thrown around for atmospheric convection cells, atmospheric residence time of water in the hydrologic cycle, and examine the possibility that there are other mechanisms for retaining the energy associated with a 30 K greenhouse than "clipping" 5 and 15 micron coupons with carbon dioxide scissors and squirreling them away until they expire.

 

[deboss]

Newbie here. I am but a poor humble engineering student. But I seem to recall a chart displaying a temperature oscillation over thirty year periods, thirty years high, then thirty years low. Being an undergraduate student my primary method of finding things is google which doesn't want to help right now. If someone could find I'd be very appreciative. Anyway if there is a non-year based thermal cycle wouldn't performing an average over our arbitrary ten base wind up skewing the data because we're catching only part of one cycle. If my memory is correct and it is a sixty year full cycle then averaging over a hundred years would include two of one cycle but only one and one third of the other. Would this be an option for the temperature difference reported.