Arguments
Joseph E. Postma and the Greenhouse Effect
Posted on 17 August 2011 by Chris Colose
Some recent attention has recently been going around the web concerning a new “paper” done by Joseph E. Postma (PDF here) which claims to “…physically negate the requirement for a postulation of a radiative atmospheric greenhouse effect.” It has been echoed particularly by some of the more crackpot web sources like climaterealists.com, and of course is spreading around various "skeptic" blogs.
The claims are of course extraordinary, along the lines of Gerlich and Tseuchner’s alleged falsification of the atmospheric greenhouse effect. As is often the case with these types of “skeptics,” the more extravagant the claim, the more obscure the publishing venue; in this case the host is Principia Scientific International, which according to the website “…was conceived after 22 international climate experts and authors joined forces to write the climate science bestseller, ‘Slaying the Sky Dragon: Death of the Greenhouse Gas Theory.’” Most rational people would stop here, but this is the Americanized age where we need to glorify everyone’s opinion and must provide rebuttals for everything, so here it goes:
I ask that the reader have the paper open in a new window so they can follow along with this article.
The Foundations
Most of Postma’s first 6 pages are actually correct. He describes the greenhouse effect through the so-called layer model, which is a simple way to break up the planet into a “surface” and an “atmosphere,” with outer space overlying the top layer. This model is described in many climate books such as Dennis Hartmann’s Global Physical Climatology, David Archer’s Understanding the Forecast, Marshall and Plumb’s Atmosphere, Ocean and Climate Dynamics, and radiation books like Grant Petty’s First Course in Atmospheric Radiation. I will say that I do not particularly like this model as a suitable introduction to the greenhouse effect. It is useful in many regards, but it fails to capture the physics of the greenhouse effect on account of making a good algebra lesson, and opens itself up to criticism on a number of grounds; that said, if you are going to criticize it, you need to do it right, but also be able to distinguish between understood physics and simple educational tools.
The atmosphere in Postma’s paper is just a single slab, so he has two layers (atmosphere+surface), but in general you can have many atmospheric layers of varying emissivity. He goes on to solve for the energy balance of each layer (see equations 11-14). RealClimate derived the same result in less than a page here.
Figure 1: Layer model is Postma's paper. Click to Enlarge
Postma actually doesn’t get the atmospheric radiative flux right. The emission is not σTa4, it is fσTa4, where f is the atmospheric emissivity/absorptivity (following his notation). The emissivity is a unitless factor between 0 and 1 descrbing how good of an absorber/emitter the object is relative to an ideal body. f = 1 describes a blackbody. By Kirchoff's law, the absorptivity of a layer must be equal to the emissivity (at the same wavelength), Both right hand sides of equations 11 and 12 are thus wrong, but it turns out that those errors cancel each other out and he gets equation 14 right. The factor of 2 in Equation 12 comes about because the atmosphere emits both up and down, although Postma clearly doesn't know how to derive this result formally, based on later statements he makes about this. Toward the end of page 14 he says this is invalid since the atmosphere radiates in 3-D, not just up and down. In fact, the quantity σT4 refers not only to the total power output of an object (the rate of energy emission), but it also refers to isotropic (equally intense in all directions) radiation. The result σT4 is obtained if one assumes that a plane radiates uniformly over a hemisphere (for example, the domed "half sphere" field of vision that a human can see when you stand outside," with the base of that half-sphere being the surface you sre standing on; the other hemisphere is invisible (see this image).
So far, it is simple textbook stuff with not much promise.
Geometry of the Global Energy Budget
Postma then goes on to describe fictitious “boundary conditions.” In particular, he seems to have serious objections to the averaging of the solar radiative flux over the Earth. In essence, he would prefer we had one sun delivering 1370 W/m2 of energy to the planet, with a day side and a night side, noon and twilight, etc. instead of the simple model where we average 1370/4=342.5 W/m2 over the planet (so that the whole Earth is receiving the appropriate "average" solar radiation). The number becomes ~240 W/m2 when you account for the planetary albedo (or reflectivity).
The factor of 4 is the ratio of the surface area to the cross section of the planet, and is the shadow cast by a spherical Earth. It is therefore a geometrical re-distribution factor; it remains “4” if all the starlight is distributed evenly over the sphere; it is “2” if the light is uniformly distributed over the starlit hemisphere alone; with no re-distribution, the denominator would be 1/cosine(zenith angle) for the local solar flux.
In simple textbook models, we like to prefer explanations that get a point across, and then build in complexity from there (see Smith 2008 for descriptions on a rotating Earth). Of course, students who use this model are probably educated to the point where they know that day and night exist, and certainly GCMs have a diurnal cycle. The radiative calculations are done explicitly by accounting for the temperature distribution and absorber amount that is encountered at each grid box. Postma is simply tackling a non-issue, just as how people criticize the term “greenhouse effect” for not working like a glass greenhouse. Postma objects to teaching this simple model because it is not real. All that is done, however, is to use a brilliant and sophisticated technique, taught only to the geniuses among us, called averaging! And of course, simple models are used in any classroom...it is how we learn.
But, in actuality, the globally averaged solar re-distribution approximation is not bad when we use it to describe the temperature for planets like Earth or Venus. These planets have an atmosphere or ocean that transport heat effectively, especially Venus with virtually no day-to-night or pole-to-equator temperature gradient. The atmosphere and/or ocean help smooth the diurnal temperature difference very well. Therefore, when coming up with a temperature estimate, it is a great first approximation. If you want the local equilibrium temperature for an airless body like Mercury or the Moon (that does not transport heat), then you want to use the no-redistribution or hemisphere only solar factor. This is well-known (see e.g., Selsis et al 2007). On Mercury, there is no heat distribution and very little thermal inertia; before the sunrise the temperature on the surface is somewhere near 100 K (-173 °C) and by noon the temperature on the surface of Mercury rises to about 700 K (427 °C). This may also be relevant for tide-locked planets (very slow rotation since one side is always facing the host star, the other in perpetual darkness). Earth does not experience any such changes of the sort. On Venus, the variability is even less and most of the planet is at around 735 K.
Summary
To summarize Part 1, Joseph E. Postma did not like a simple model of Earth’s radiative balance where we approximate the Earth as a sphere with uniform solar absorption. Of course, this is never done in climate modeling or in more detailed analyses appropriate for scholarly literature, so it is more an exercise in complaining about undergraduate education than an attempt to correct what he calls a “paradigm” in climatology. Nonetheless, the 0-D energy balance model is a useful approximation on Earth when coming up with an average emission temperature (~255 K), since air circulations and oceans tend to even out the diurnal temperature gradient on Earth, in addition to the thermal inertia provided by the system.
In Part 2, I will examine several of the other claims in the paper.
These posts comprise the Advanced rebuttal to Postma disproved the greenhouse effect
[DB] Because this Postma doesn't deliver...?
[DB] Miss the rimshot?
So, yes, it is the simple 1-D "energy model" which I am criticizing. I criticize it because it doesn't correspond to reality (for the simple fact that the Earth isn't flat), and so, at the very least it is a bad thing to teach people because it teaches invalid mathematical techniques pretending to be physics, and at worst, the greenhouse effect concept really is based on it.
The basic process in these models is to average the solar energy over the entire surface of the planet, thus "destroying" any factors for time and geometry. Mathematically, this process creates a flat geometry with a solar input at -18C.
Then the reasoning goes: If solar input is only -18C but the surface is warmer than that, then something else, the atmosphere, must be adding/trapping heat, to bring up the temperature to +15C. This "raising of the temperature" is the greenhouse effect.
So, you have the greenhouse effect postulated because solar input is only -18C, while the surface temperature is actually +15C.
The problem is that the solar input is not actually -18C, and the Earth shouldn't be modelled as flat (because it isn't flat), and in physics it is wrong to mathematically "destroy" physical factors such as rotation and geometry.
To make the point most simply: solar input at -18C does not reperoduce the physics at the surface that we actually see being induced by sunlight. Such as, melting ice to water, which requires sunlight input with a flux corresponding to at least 0C, and also mass-evaporation of water to water vapor to create cumulonimbus and other types of clouds, etc, wich requires solar input at a still much higher temperature. And scalding-hot sidewalks, hot beach sand, and things like that.
So, these facts being self-evident, we really need to appreciate that these 1-D energy models aren't saying much about the actual physics at the surface at all. In fact, the basic postulate where we invent the greenhouse effect to create higher temperatures can't really be accepted anymore at all. The sunlight is creating temperatures that are actually much, much higher than +15C, let alone -18C.
And so we also must consider the latent heat of liquid and vaporous water: sunlight is self-evidently more than powerful enough to breach those barriers and fill up those latent heat "reservoirs", and so what happens when those heat energy reservoirs drain back out overnight and at the poles? Well, I think it's obvious: they're going to keep the surface warmer by preventing it from dropping in temperature before those reservoirs drain out. However, those heat reservoirs never actually drain out because they're constantly being replenished. Hence, latent heat is constantly keeping the temperature warmer than otherwise.
As far as a very simple average of giving the Earth's "effective blackbody temperature", this is fine: 255K, for 240 W/m^2 output. But the Earth has an atmosphere and only humns think the ground surface is the surface, whereas radiation will find a different surface depending on emissivity, absorption, scattering, etc etc., and so this temperature of 255K should not be expected to be found at the ground surface in the first place. The atmosphere is itself a/the surface, if you're radiation.
So, just considering a simple mathematical fact, that the average of a sequentially distributed metric will be found not at either extremity of the distribution, but somehwere inside it, somewhere middlish, then, the average temperature of the Earth will not be found either at the top of the atmosphere, or at the bottom of the atmosphere, but, somewhere between those. Given that really basic energy equations show that the atmosphere naturally has a temperature gradient (the -g/Cp thing), then, once again we find ourselves in a position where the -18C average should never have been assumed to be found at the ground surface (nor at the top of atmosphere), thus rendering the resulting postulate of the atmospheric greenhouse effect, to make up the difference, superfluous.
See this paper:
A Discussion on the Absence of a Measurable Greenhouse Effect
That paper has some good science in it, but I also go on about "philosophy" and "principles" and all this stuff that gets too distracting for a basic science paper.
But the basic science is there: the radiative surface is not the ground surface, the average of the system should not be found at the bottom, need to account for latent heat, no "higher maximum temperature than maximum insolation" is empirically found. And whatever else I'm forgetting at the moment.
Anyway, lastly, as far as just getting the actual vertical-column energy behaviour correct, setting aside the global climate so that we can just get the fundamentals correct (which of course the 1-D flat Earth models do not), then we need to go the actual equations for heat flow in a column, which would look like this:
One could model down to, say, ~10 meters where the soil temperature is static, up through the surface, and through to several hunfred meters in altitude where the air temperatre is static. So, all parameters such as density and thermal capacity would be functions of x, Q is a forcing term which would be supplied by sunlight modelled in real time (not averaged!). I don't think there would be a Q from the atmosphere since the atmosphere isn't actually a source of energy - there's no combustion, fission/fusion, or anything occuring in the atmosphere that actually produces heat. You would need to track the energy content to get the latent heat levels, latent heat release, and latent heat "supply", and things like that, but it could be done. It would be the correct way to do it at least. All numerically since there would be no analytical solutions with everything as a function of x etc.
Interesting thing though about proper heat flow equations like this, is that temperature is never induced upwards in the direction from cold to hot at the hotter end - heat only flows from hot to cold and only cold becomes warmer from hot, i.e. hot doesn't get warmer from cold. Of course, that gets rid of a bunch of really bad arguments as to what people think the "greenhouse effect" is. Well, at this point I think it is pretty clear that there is no radiation greenhouse effect - there is just a "latent heat temperature retention effect", and a "temperature gradient effect".
A hopefully final clarification: the 1-D, one-layer model is not "my" model, it is "their" model, and I've copied it directly with references as to source.
"They" use it to justify and explain the origin of the greenhouse effect, but as we have seen, no such model can actually produce anything corresponding to reality for the simple fact that it has nothing to do with reality. You can't "go around saying" that the solar input is only -18C at the surface, and then create some postulates based on that, because the solar input factually isn't that and because if it were that it wouldn't reproduce otherwise known physics at the surface.
Notably, adding more atmospheric layers to such a 1-D model doesn't actually correct the mistake: the 1-D model and the -18C solar input is the mistake. The geometry is wrong and the energy levels are wrong. Any postulates which come from such a model will likewise be mistaken, by heredity.
So, there is no a-priori reason to postulate a radiative greenhouse effect any longer because the models which are typically used to do so, the 1-D models, don't actually have anything to say about the actual physics reality occuring on the surface. This has been partially admitted here by C.C. and other commentators. Thus, is there another method to postulate a raditive greenhouse effect, without referring back to the false physicsof the 1-D models? Then again, one should also ask why we would continue to assume in a-priori that very postulate that originates in those false models. Why continue trying to justify it if the premises of its original origin has been discarded? That goes beyond the remit of science and into something else.
JPostma, suffice to say that if you really are trying to say that one-dimensional models are the reason scientists conclude the atmospheric greenhouse effect exists, which is what I read from statements such as
then you are wasting everybody's time, including yours, coming on here and posting nonsense.
Just curious then. As Chris says in his article, the 1D model is a teaching tool, not the understood phyics. He points to the papers which deal with the real complexities.
Secondly, the criticized model does a remarkable job for predicting the radiation, including the spectral signature, measured at both TOA and ground surface. Can a Postma alternative do that?
And perhaps you would like to respond to Roy Spencer on the idea that IPCC uses 1D models, which he thought "border on the ludicrous."
JPostma:
1) A one dimensional model is a model expanding (most typically) a zero dimensional energy balance model by showing different lattitudes. What you use is a one layer energy balance model, a model only used in climate science for purposes of instruction. It is usefull for instruction because it allows the introduction of relevent equations in a simple form, but those equations are not used in one layer models in any actual scientific work.
2)
In physics, it is standard procedure to use simplified models for initial, or approximate calculations. The classic example is from Newton, who initially calculated the planetary motions based on his theory of gravity using the assumption that the Sun and the Earth were point masses. So, even if you were actually correct about the use of one layer models (which you are not), your criticism would only be a stipulation that in climate physics, standard methods of physics should not be used.
3) Historically, the model that was used to show the existence of the greenhouse effect was the zero dimensional energy balance model, which calculates that:
T(e) = (S*(1-A))/(f*σ))^(1/4)
Where T(e) is the effective temperature, S is the insolation at the planets orbit (1361 W/m^2 for Earth), A is the bond albedo (0.3 for Earth), f is a geometrical correction factor (4 for Earth), and σ is the Stefan-Boltzman constant.
For rapidly rotating planets with strong redistribution of energy at the surface, f is set at 4 (effectively assuming a constant temperature across the planets surface). It is calculated as the ratio of the surface area of a sphere to the surface area of a circle of the same diameter (ie, of the Earth's surface area relative to the area of sunlight it intercepts).
Uneven heat distribution, such as actually obtains, reduces the effective temperature. So, if we expanded this model to a one dimensional model, it would predict a cooler effective temperature. The heat flow from the tropics to the poles therefore warms the Earth on average, even though it always represents heat flowing from a warmer to a colder place. It cannot heat the Earth to more than the effective temperature, however, and hence the estimate of a 33 C greenhouse effect is an underestimate. Latent heat also evens out heat extremes, and therefore also warms the Earth, but again cannot warm it above the effective temperature calculated by the zero dimensional energy balance model. And when I say cannot, I mean that it would contradict conservation of energy if it did.
4)
Again, scientists do not use the one layer model (which you incorrectly name) to justify belief in the greenhouse effect. They only use it as a simple model to explain the greenhouse effect. When justifying beliefs they use evidence, and three dimensional models that take into account all the complex factors of climate (within the limits of resolution required by limmited computer power).
First, the evidence:
Scientists have observed using instruments in planes, balloons and satellites, the upward long wave radiation from the Earth. Here is one such observation compared with a Line By Line (LBL) radiation model calculation of the upward radiation:
The area under the curve represents total outward energy. Because the outward energy at 660 cm-1 (Wave Number) is low, energy at other wave numbers must be higher to allow a given amount of radiation to escape the Earth. Because the reduced outward radiation at 660 cm-1 occurs everywhere on Earth (as determined by observations for all locations on Earth), overall radiation in other parts of the spectrum must be higher for a given amount of energy to escape. Because the radiation is thermal, for the radiation to be greater the temperature must be greater. Therefore, because of the oberved effect of CO2 on outgoing radiation, the temperature of the Earth's surface must be greater than it otherwise would have beeen.
That is the greenhouse effect - something which has therefore been directly observed by satellite based instruments hundreds of thousands of times.
Second, GCMs also show that without well mixed greenhouse gases in the Earth's atmosphere, the Earth's surface would be cooler by about 33 C. That, again is an underestimate in that the GCM was constrained to not allow expansion of ice sheets (and the consequent increase in albedo). Further, that even allows for the small remaining natural greenhouse effect from water vapour. The GCM involved happened to be the GISS model ER, which has a climate sensitivity around 2 C.
The use of this model to demonstrate the effects of greenhouse gases shows your continuing use of the one layer model to be the deliberate use of a strawman. Climate scientists have been using far more complex models than the one you use for decades. Further, they do not use the model you use for research, but only for teaching. Your persistence criticizing a teaching aid and treating that as if you were actually criticizing the theories of scientists would be on a par with a polar explorer "proving" that geographers were totally mistaken about the Earth's shape because pictures of the poles do not show large metalic cylinders about which the Earth rotates are represented on globes in classrooms through out the world.
And not only satellites but direct surface observation. That is, downwelling longwave radiation has been instrumentally measured at the surface (see Wang & Dickinson 2013 for a review of observation-based studies).
Well, there is no other way that the radiative greenhouse effect is actually postulated. The 1-D models are its source. And as we've seen and had agreement on, the 1-D models do not correspond to physical reality in any way.
The Earth is not flat.
Solar input flux heating is not -18C.
If it were -18C it wouldn't be able to melt ice, create clouds.
The solution to that problem is not to postulate a radidative greenhouse effect, but to get the initial conditions right: the Earth is not flat and solar input is not -18C.
There is a minimum level of complexity required for a model to have any meaninglful correspondence with reality. The 1-D models do not satisy that. All they state is that energy in = energy out, and that's fine and obvious.
Therefore, the idea that radiation from the atmosphere heats the surface needs to be discarded, because that idea only comes out of the postulate required to save a bad model, a postulate which is itself therefore wrong. We see people agreeing that the 1-D models do not correspond to actual reality, but then they immediately turn around and try to justify the postulates from the 1-D model. This is not the way to go about things.
It doesn't matter if you add more layers or have higher dimeniosnality models. The postulate of the radiative greenhouse effect still has no basis. And we have been looking through the IPCC models, and there is no actual greenhouse effect in them, anywhere. Neither Spencer nor anyone else can identify it and say where in the models it is, or how it originates. What they will do however, is always refer back to the 1-D models! It's kinda crazy.
The 1-D model is not a simplified model. It is a wrong model which violates very, very basic, in fact fundamental features of the actual physics occuring at the surface. Such as sunshine melting ice and creating clouds. It is a wrong starting point, initial approximation - not a close one.
The fffective temperature is not an actual temperature measurement, but an inference given energy conservation and assuming unit emmisivity. For Earth, this is ~255K, corresponding to the expected ~240 W/m^2 average output from the globe. This temperature should not be expected to be found at the ground surface since for radiation, the surface is not the ground surface, and also, because of the natural lapse rate gradient of -g/Cp (can also factor for latent heat release which lessens the slope, as I showed in that paper) which mathemtically necessitates that the average will not be found at either extremity (ground surface or TOA), but somewhere in the middle, thus automatically making the surface warmer than the average.
A spectral plot is not evidence of a greenhouse effect. It is evidence of spectral absorption and scattering. You get spectral absorption and scattering when you have a cooler gas in front of a warmer source. The cooler gas does not cause or induce the temperature of the warmer source. As we have seen, solar input is actually much higher than -18C, latent heat release will hold the surface at a warmer temperature than otherwise, and the lapse rate gradient automatically necessitates a warmer bottom-of-atmosohere than middle and top. The 1-D model as designed by climate scientists is indeed, exactly and directly, about the attempt to use the spectral absorption of a cold gas as a way to make up for the erroneous "solar-heating deficit" produced by those very models. Yes the surface can warm the colder gas via absorption in that gas of "warm" surface radiation, but this does not translate back to a requirement that the surface must increase in temperature, because it is heating that gas. And such a scheme completely dismisses the existence of the lapse rate, of latent heat, and real-time physics where the sunshine actually does induce behaviour that the averaged solar input of -18C does not have the power to achieve.
And finally, let us be reminded that a real botanist's greenhouse should be able to function by that math and logic of the 1-D model and by the same of the spectral absorption argument: this should induce a higher temperature inside a greenhouse "glass box" than the maximum solar input is providing. The glass roof serves the role of the layers of the atmosphere and of miles of spectral absorption and scattering. But it doesn't happen - the maximum temperature is only equal to the solar input. Empirical measurement demonstrates that spectral absorption and/or layers of atmosphere absorbing radiation from the surface do not cause the surface to become warmer. When you factor in the fact that setting the solar input to -18C is not going to be able to reproduce any of the significant physics that actually occurs in real-time from actual high-power "hot" sunshine, then the rest of the thoughts and postulates which have ever extended from that likewise be extinguished. You should start over. The models aren't working anyway, the temperature isn't increasing like it was predicted. It is a good reason to reevaluate. Start over using actual heat flow physics in real time with the heat flow PDE, and show people all the work.
JPostma:
The atmospheric greenhouse was demonstrated experimentally by Tyndall in the mid-19th century, and as Tom Curtis has shown, has been documented empirically on multiple occasions.
Further, the fact of its existence follows, necessarily, from the radiative properties of greenhouse gas molecules in the atmosphere.
It is, in short, a real 'thing'.
In your attempt to "disprove" the greenhouse effect, you are engaged in three ongoing misbehaviours on this thread:
(1) persevering in your make-believe notion that the simple 1-dimensional model is the basis of scientific acceptance of the atmospheric greenhouse effect, rather than its actual status as a high school or undergraduate teaching tool;
(2) from (1), persevering in arguing that your rebuttal of this teaching tool constitutes a rebuttal of the actual atmospheric greenhouse effect whose existence has been experimentally and empirically confirmed; and
(3) re-asserting your argument without any new counter to the rebuttals raised either by the OP or by comments, which IMO constitutes sloganeering.
Just as an example of something interesting when you consider latent heat of liquid water rather than ignoring all such other physics in an attempt to make it all about radiation, consider the effect that latent heat has at the surface - the result below was calculated using real-time, actual solar input at the surface of the Earth:
Above you can see that latent heat from liquid water prevents the temperature from dropping below zero, which will thus give a daily-averaged temperature reading which is higher than you would expect, because the curve doesn't drop below zero when basic daily input energy considerations would make you think it should. Latent heat is like a heat battery than turns on at 0C and keeps it there. Of course, latent heat from water vapour releases out of the atmosphere at a temperature higher than 0C.
This shows that latent heat keeps the surface warmer than otherwise, as a function of the mass of water on the surface. And that's just for liquid on the surface. The atmosphere releases the latent heat of water vapor too, which will bump the temperature anomaly up higher still. Integrated over all mass quantities, the integrated temperature anomaly offset is about +60C.
So the point is, making the surface temperature all about atmospheric radiation and a radiative greenhouse effect is wrong.
The 1-D models aren't a useful approximation, they are an anti-physics error, a massive wrong way to think about the physics. They are a fiction which produce a cognitive "scientific" landscape totally divorced from reality.
Check out this data from a temperature measurement station with sensors going to .86m into the ground, and up to 1.5m altitude. This data was collected over a few months:
https://www.youtube.com/watch?v=AoJM4taoNFo
You need the 2D heat flow PDE to model something like that, and that is what needs to be modeled if you want to understand heat flow in the atmosphere and surface. (Though we'd need data going deeper into the ground, and higher into the air, and for longer time.) The 1-D models are simply 100% divorced from being able to explain what is seen in that data sequence...they contradict it in fact. The point being that the 1-D models need to be completely rejected as fictional, and hence, any of the type of thinking associated with them or commonly referred back to them, such as the radiative greenhouse effect, likewise must be rejected.
JPostma - I'm sorry, but your entire argument is a strawman fallacy. The 1-D model you discuss is simply an explanatory tool, not the justification for the understanding of the radiative greenhouse effect.
The scientific understanding of the radiative greenhouse effect is based upon spectroscopy, radiative physics, atmospheric composition, and observations of (among other items) lapse rates, evaporative exchanges, convection, TOA and surface IR, etc. Not on a simplified model used in classrooms - a model that is simplified, but correct in that it relates some important factors demonstrating the effects of changing effective surface emissivity.
It doesn't help that your geometry is wrong, and thus is your estimate of insolation, that glass greenhouses are a red herring with respect to radiative phsyics, etc. You have presented exactly nothing of substance.
Your whole argument is based upon a misrepresentation of the science. As such, it's not even wrong.
"The atmospheric greenhouse was demonstrated experimentally by Tyndall in the mid-19th century, and as Tom Curtis has shown, has been documented empirically on multiple occasions."
In fact, real greenhouses demonstrate that they do not get hotter than the solar input. This contradicts the radiative greenhose hypothesis while supporting the trapped-warm-air hypothesis of why greenhouse interiors are warmer than outside.
"Further, the fact of its existence follows, necessarily, from the radiative properties of greenhouse gas molecules in the atmosphere."
That some molecules in the atmosphere scatter/absorb radiation, does not mean that they heat the surface. In fact, low emissivity is what leads to higher temperatures than otherwise, and O2 and N2 have basically zero emissivity, meaning that they hold on to and trap heat already...they being 99% of the atmosphere.
"It is, in short, a real 'thing'."
This is only a statement of claim. I have demonstrated physical, mathematical, and logical reasons for why the radiative greenhouse effect is erroneous.
"(1) persevering in your make-believe notion that the simple 1-dimensional model is the basis of scientific acceptance of the atmospheric greenhouse effect, rather than its actual status as a high school or undergraduate teaching tool;"
I have stated that adding more layers or higher dimensionality does not actually fix the mistake of getting the solar input wrong. The 1-D model is not an approximation but an outright error, an outright mistake. It should not be used for a teaching tool at all, and any idea of a radiative greenhouse effect which comes out of it is entirely, completely wrong.
(2) from (1), persevering in arguing that your rebuttal of this teaching tool constitutes a rebuttal of the actual atmospheric greenhouse effect whose existence has been experimentally and empirically confirmed; and
But it has not actually been experimentally and emirically confirmed, as real greenhouse temperatures contradict the radiative greenhouse postulate of being able to induce a higher temperatre than the solar input. To continue to argue that the 1-D model is a teaching tool is to make the point that what is being taught is wrong.
(3) re-asserting your argument without any new counter to the rebuttals raised either by the OP or by comments, which IMO constitutes sloganeering.
The same can be said for you. However, I have actually been making rational logical physical points while the common slogans of the radiative greenhouse effect which originate out of that erroneous teaching tool keep on being presented over and over as if that teaching tool has any legitimate claims to reality, which it does not.
Yes, the point is that if the 1-D model is a teaching tool, then what is being taught is wrong.
It is the 1-D models which misrepresent physics. As many people have been taught by this tool, their idea of how things might work will likewise misrepresent physics. The initial conditions and the boundary conditions of the physics have all been messed up by that model. Better physics such as absorption, scattering, etc., does not equate to a source becoming warmer because its radiation is absorbed somewhere else. And indeed real greenhouses do not demonstrate the radiative greenhouse postulate.
JPostma:
Your response to my comment shows up the blatant falseness of your claims.
Witness such gems as:
and
The behaviour of artificial greenhouses are irrelevant with respect to the existence of the atmospheric greenhouse effect. As KR notes, it is a red herring fallacy.
Or how about this:
Per Kirchhoff's law of thermal radiation, it is in fact the case that low emissivity equals low absorption at equilibrium (say, the atmosphere with an effectively constant incoming solar flux). If, as you say, O2 and N2 have low emissivity, it follows from this law that they have low absorptivity, and cannot on their own trap radiated heat in the amounts required to maintain the observed Earth surface and atmospheric temperatures. By your own words you contradict yourself.
Several of your other comments suggest you are ignorant of, or unwilling to consider, the Stefan-Boltzmann law, from which the average Earth temperature sans atmospheric greenhouse effect is derived.
So much for rational, logical, and physical argument on your part.
"If, as you say, O2 and N2 have low emissivity, it follows from this law that they have low absorptivity, and cannot on their own trap radiated heat in the amounts required to maintain the observed Earth surface and atmospheric temperatures. By your own words you contradict yourself."
They gain heat by conduction with the surface, and then they can't radiate it away because of their low/zero emissivity. The atmosphere heats by conduction with the surface too. The atmosphere does not only get heated by absorption of surface radiation, you can not ignore the other modes of heat flow as an attempt to make it all about radiation.
"The behaviour of artificial greenhouses are irrelevant with respect to the existence of the atmospheric greenhouse effect. As KR notes, it is a red herring fallacy."
An "artificial" greenhouse, by which you mean a botanist's greenhouse, should work exactly like the maths of the 1-D model, and by the rest of the radiative greenhouse effect argumentation aside from the 1-D model, with the glass ceiling taking the place of layers of atmosphere and absorption/scattering etc. An artificial greenhouse demonstrates that such arguments do not manifest - the internal temperature does not get higher than the maximum solar insolation.
"Several of your other comments suggest you are ignorant of, or unwilling to consider, the Stefan-Boltzmann law, from which the average Earth temperature sans atmospheric greenhouse effect is derived."
Of course, that law is discussed at length in my papers and has even made its appearance here, in worded form. I am sorry if you missed that. Indeed, it sets the effective temperature of the Earth - but this is not to be thought of as appearing at the ground surface, but somewhere in the middle of the atmosphere.
I'm sorry that you've missed these points.
Postma: "Yes, the point is that if the 1-D model is a teaching tool, then what is being taught is wrong."
All models of real-world phenomena are wrong. I'm fairly certain that instructors aren't telling students that 1D models are accurate representations of atmospheric physics. I'm fairly certain that they're saying some form of "This is a lie, but it's a useful lie."
"All models of real-world phenomena are wrong. I'm fairly certain that instructors aren't telling students that 1D models are accurate representations of atmospheric physics. I'm fairly certain that they're saying some form of "This is a lie, but it's a useful lie.""
Well, some models actually do make reasonable statements about reality. The 1-D greenhouse model does not, and in fact it violates reality at some pretty fundamental levels. To use it as a teaching tool is only to teach the wrong thing and wrong ideas and wrong method. Some models help. Some hinder. This one hinders.
In fact they do not say that it is a useful lie. Such an idea is irrational and illogical in any case. As seen here, they say that it provides a reasonable approximation to reality, to understand some basic features. That is wrong. It wrecks all of the basic features.
JPostma:
You claim, of N2 and O2:
Currently, radiative heat transfer from the Earth surface to the atmosphere is 358.2 W/m2 (the amount absorbed by the atmosphere). Conduction & convection heat transfer, taken together, from Earth surface to the atmosphere is 18.4 W/m2. In fact, the total current non-IR heat transfer from the Earth surface to the atmosphere is 181.9 W/m2. If you have disproved the greenhouse effect, the atmosphere is positively frigid, from top to bottom. It follows that the surface also becomes very cold since the atmosphere is no longer insulating it.
But, N2 and O2 collide with radiatively-active (that is, greenhouse gas) molecules (water vapour, carbon dioxide, etc.) and the latter radiate heat away from the atmosphere into space. If we accept that you have disproved the atmospheric greenhouse effect, greenhouse gases do not absorb at IR bands and hence they do not emit at them either (via Kirchhoff's laws). Thus by your own contention, heat energy entering the atmosphere has no means of escape, at least not until the atmosphere warms up enough to start warming the surface instead!
There you have it. If we accept your conclusion about the atmospheric greenhouse effect, either greenhouse gas molecules (unphysically) do not absorb IR radiation, but only emit it, or greenhouse gas molecules (also unphysically) neither absorb nor emit IR radiation. The end results are contradictory and nonsensical, but they follow necessarily from accepting your position.
You have been told several times that atmospheric scientists do not rely on the behaviour of artificial greenhouses to establish the properties of the atmospheric greenhouse effect. That you persist in claiming the reverse, alongside your unwillingness or inability to admit that experiments and observations confirm the existence of the atmospheric greenhouse effect, and your unwillingness or inability to think through the implications if you were correct, speaks volumes as regards your comprehension, scientific integrity, and credibility.
I'm done.
Of course, what I find truly remarkable about these Sky Dragon Slayers is how much slaying they do. Any science that gets in the way - slay it.
Here's a thing, mind. The very first star bursts into life in the early universe and sends forth a red-wavelengthed photon. Off it goes across inter-stelar space for 13 billion years, near-missing planets, deflected by black holes and countless other adventures before entering the Earth's atmosphere, straight in through my open bathroom window, only to be reflected off a mirror and back up into the sky. There ahead is its destination, our sun. But steady on!! This sun is a bit yellow. Oh no!! It's too hot!!!! If the poor little photon impacts the sun it will be allegedly breaking the laws of thermodynamicks, the most important laws there are in the entire universe.
So does the photon perform a special dance to avoid breaking the Sky-Dragon-Slayer-version of laws of physics?
Or, when the photon was emitted by that ancient star so long ago, was the state of the universe 13 billion years hence alreay 'known'? Was it emitted only because it would truly be destined for a colder place? Will that poor little photon be really destined not for the sun but for a passing Vogon spaceship that is about to happen-by just in the nick of time?
Yes, N2 and O2 are also heated from other gases, and again, they can not emit this heat as radiation to lose it. Radiatively active gasses can radiate though and thus, they can lose heat. So, N2 and O2 trap heat, because they can't shed heat through radiative emission. Radiatively active gasses though can lose heat by emission. No one said that IR active gases do not absorb and emit. Rather, zero-emissivity gasses do not absorb and emit and ths they trap heat. I am sorry if you thought it seemed like I was saying that radiatively active gases do not absorb and emit. The point is that zero-emissivity gases do not radiatively absorb and emit, but they do get heated from physical interaction with the surface and other radiatively active gases, and thus, they hold on to that heat, and the IR active gases are the ones that help cool it. So yes, as you say, if there are gases which are radiatively inert, such as O2 and N2, then the atmosphere will warm up above insolation temperature. Thus N2 and O2 are the heat trapping gases while the radiatively active gases are the ones that can emit and thus cool.
"You have been told several times that atmospheric scientists do not rely on the behaviour of artificial greenhouses to establish the properties of the atmospheric greenhouse effect. That you persist in claiming the reverse, alongside your unwillingness or inability to admit that experiments and observations confirm the existence of the atmospheric greenhouse effect, and your unwillingness or inability to think through the implications if you were correct, speaks volumes as regards your comprehension, scientific integrity, and credibility."
As has been pointed out: An "artificial" greenhouse, by which you mean a botanist's greenhouse, should work exactly like the maths of the 1-D model, and by the rest of the radiative greenhouse effect argumentation aside from the 1-D model, with the glass ceiling taking the place of layers of atmosphere and absorption/scattering etc.
An artificial greenhouse demonstrates that such arguments do not manifest - the internal temperature does not get higher than the maximum solar insolation, even though any version of argument for the radiative greenhouse effect says that it should.
So, the radiative greenhouse effect is not observed in an experimental apparatus (a botanists greenhouse) where it should be observed - and this is of course independent of whatever argument you wish to use for the radiative greenhouse effect. The core principle, that of a higher temperature being induced inside than the insolation temperature, is refuted by empiricism (and also by theory if you can follow it properly).
Glad to have had the chat.
"So does the photon perform a special dance to avoid breaking the Sky-Dragon-Slayer-version of laws of physics? Or, when the photon was emitted by that ancient star so long ago, was the state of the universe 13 billion years hence alreay 'known'? Was it emitted only because it would truly be destined for a colder place? Will that poor little photon be really destined not for the sun but for a passing Vogon spaceship that is about to happen-by just in the nick of time?"
Well it is rather simple: a cold source does not heat up a hotter source. Radiation from a cold object does not warm up a warmer object. This really is basic heat flow mechanics and thermodynamics. It works the same for radiation as it does for conduction. If you have a hot object touching a cold object, the hot object is heating the cold one only; if you separate them with a gap, the radiation from the cold object does not sunnedly start to warm the warmer object.
It is good to think about life as a photon. How is the universe experienced as a photon? Apply relativity. Time is infinitely dilated, i.e. time has stopped, and all distance along the path-inegrated vector of travel has been shrunk to zero. So there is no time nor any space as far as the photon sees things - they do travel at the speed of light, and relativity does apply.
Also, in fact, the botanist's greenhouse is the original greenhouse, and is the origin of the term "greenhouse", because they grow green food. Therefore these are not "artificial", rather, they are the proper and legitimate name given to them originally.
However, the radiative greenhouse effect as originates out of these 1-D models is indeed artificial, as we have seen people acnowledging that such models are indeed artificial and are not actually representative of the physics of the atmosphere.
A real, original greenhouse (a botanist's greenhouse), stays warm by trapping heated air, while it doesn't get hotter than the solar insolation due to thermdynamic contraints.
The atmospheric radiative greenhouse effect has adopted the name "greenhouse effect", but it in fact does not follow the physics of the original greenhouse, and therefore the atmospheric radiative greenhouse effect has some degree of artificiality to it.
The postulates of this new atmospheric radiative greenhouse should likewise be able to be applied to a real original greenhouse, since they would do what is postulated that the atmosphere does in terms of trapping radiation, etc. However, as an experimental apparatus which can test the new conception of a radiative greenhouse, measurements show that the expected resulting temperature from this new interpretation is not observed inside them. A real greenhouse is still only warmed due to trapping warm air, while the expected results of the artificial radiative greenhouse effect, using any argument or model for it, do not manifest, thus confirming their artificiality.
JPostma @39.
If a photon is travelling at the speed of light, how is that photon experienced by the universe? Apply relativity. Time is infinitely dilated, i.e. time has stopped, and all distance along the path-in(t)egrated vector of travel has been shrunk to zero. So there is no time nor any space as far as the universe sees things - they do travel at the speed of light, and relativity does apply. I have this dreadful feeling - you understand relativity less well than even your purile inderstanding of thermodynamics.
JPostma, do you agree:
1/ That despite your difficulties with the layer model as a teaching tool, climate scientists do not have a such problem as evidenced by eg Smith 2008 and by the codes.
2/ In a botanical greenhouse, the primary effect is convection which massively overpowers any radiative effect. The Greenhouse Effect is inaptly named but that doesnt make it wrong.
3/ The most important test of the model is whether the numbers it produces match what you observe in empirical testing. This is after all how the model informs climate science.
4/ The actual radiative codes used (Hitran) predict the radiative power and spectra for both incoming and outgoing radiation to a remarkable degree of accuracy.
JPostma @40, the botanist's greenhouse is not the "original greenhouse" to which analogy was made with regard to the greenhouse effect. Rather, in the very first postulation of a greenhouse effect, by Jean-Baptiste Fourier in 1827, an analogy was drawn with Horace Bénédicte de Saussure's hotboxes:
The fact that the temperature increase became greater with additional panels of glass refutes the simplistic notion that the effect is entirely the consequence of preventing heated air being carried of by the wind. Nor is it likely due to the insulating properties of the glass, as glass is a good thermal conductor.
Later, William Herschell designed a de Saussure hotbox that achieved a temperature of 240 Farenheit in South Africa, a temperature generating black body radiation of 1294 W/m^2 of thermal radiation. That is significantly greater than the 1000 W/m^2 solar insolation at ground level (ie, after absorption and scattering as it passes through the atmosphere). (De Saussure's 110 centigrade represents a black body radiation of 1222 W/m^2.)
There are in fact thermodynamic limits to how warm the greenhouse effect (or other methods of retarding energy loss) can make warm an object. That limit is set, however, by the balance of energy in to energy out (first law of thermodynamics); and by the entropy of individual photons (second law of thermodynamics). Because the individual photons from sunlight come from the Sun's surface, in principle it would be possible to heat a surface to the temperature of the Sun's surface with no violation of the 2nd law. In practise, we can never achieve perfect efficiency and so that is not possible. Never the less, solar concentrators can achieve temperatures in excess of 3,200 centigrade despite being subject to the same thermodynamic limits.
Returning to de Saussure's hotboxes, Fourier noted:
So, from the first analogy, the two methods by which the hotboxes (and greenhouses) work are clearly noted; and no claim is made as to which is the stronger. That Fourier's care in explanation was lost by later popularizers has no bearing on the physics involved.
It would in fact be interesting to properly test the actual existence of the greenhouse effect in a de Saussure hotbox more rigourously than has been done previously. That would involve constructing two hotboxes, one using glass for the panels, and one using another material, equally transparent to the visible, transparent to IR, and equally conductive of heat. That is because a major form of heat loss in hotboxes (particularly of single panels) is from conduction to the external air from the glass pane (glass being a good conductor). It is not clear whether the superior conductivity of glass relative to acrylic allows the escape of more heat than is retained by the IR opaqueness of glass, and whether it does or not may well depend on conditions. To avoid this issue, the hotboxes need to be placed in a vacuum so that radiation is the only method by which heat can escape. You also need to screen both boxes from the source of radiant heat with a panel of glass to ensure that both have the same radiant energy absorbed at the bottom of the box. I am unaware of any attempt to test the theory that is rigourous to that extent. Never-the-less, the known facts for de Saussure's hotboxes show with very high probability that the radiant insulation is the most important factor were multiple panels prevent carrying heat of by conduction through a single glass panel.
JPostma @26, as a matter of logic, if you have two models both producing the same effect, then one feature which is present in one model but absent in another cannot be the cause of the effect. Thus, if you have a model with a single layer, and a flat surface, and a second model with 40 layers, and with 10,368 cells, cells per layer, each arranged so that together they are a close approximation of a sphere; and if in the second model the insolation at the top of the atmosphere matches that from the Sun, and both show the greenhouse effect, then the flat surface or the reduced insolation, or the single layer in the first model are not necessary to produce the greenhouse effect. On the contrary, the greenhouse effect can be produced with a spherical Earth, with full insolation and geometry, and with multiple layers. In this situation, focussing exclusively on the simple model in order to "disprove" the existence of the greenhouse effect, and claiming it to be disproved because the simple model has unphysical features that are not present in the complex model shows either rank ignorance or complete dishonesty.
I have already linked to Lacis et al (2010), who show the effect of removing the well mixed greenhouse gases from the atmosphere:
As can be easilly seen, the first effect is to increase the upward Top of Atmosphere (TOA) radiation by 60%. Planetary albedo only increases by 40% (from 0.3 to 0.42), so there is a 20% increase in the upward TOA long wave radiation. That is the increase which is predicted by the theory of the greenhouse effect, and it occurs as predicted. Concurrent with that change, temperatures drop by 35 degrees C. That is of the same order of the consequence of the greenhouse effect as predicted by zero dimensional models. It differs slightly because, first, the zero dimensional models do not include any change in albedo, and second, because some greenhouse warming from water vapour is retained.
So, the more complex model clearly shows the greenhouse effect, and clearly shows it to have a large impact on surface temperatures.
In response to that you say:
However, that is transparently, and entirely mistaken. Adding extra dimensions (geometry) does matter because it makes the models more realistic, while retaining a greenhouse effect. So also with adding more layers. More importantly, the IPCC models clearly have an identifiable greenhouse effect as shown by Lacis et al. I cannot speak for Spencer, but the notion that Lacis and co-authors cannot identify the greenhouse effect in their models is laughable.
What is worse, I have, in my previous post clearly identified the greenhouse effect in actual observations. I also linked to a post of mine which clearly explains the greenhouse effect, which you have clearly ignored. For your convenience, I will quote from it:
If that is not clear enough, the greenhouse effect is the difference between the upward IR radiation at ground level and the upward IR radiation at the top of the atmosphere. That difference can be identified easilly in any GCM. Further, no model encoding actual physics confirmed in laboratories (such as the Stefan-Boltzmann law) can show the difference without having a ground temperature warmer than the effective temperature (ie, the temperature predicted from insolation). The reduced upward radiation causes the increased surface temperature.
At this point, there has been no lack of clarity on my part. If you come back and say "yes, but one d model", you will clearly show that you are dishonestly using a strawman argument. If you cannot show your argument true using the 42 layer, 10,368 cell, spherical geometry GISS Model E2 used by Lacis et al (2010), you are merely showing your argument depends entirely on using simplistic models only used for teaching as we have said all along.
"I have this dreadful feeling - you understand relativity less well than even your purile inderstanding of thermodynamics."
Simply apply the Lorentz transformations with v = c, and see what the results say.
"Later, William Herschell designed a de Saussure hotbox that achieved a temperature of 240 Farenheit in South Africa, a temperature generating black body radiation of 1294 W/m^2 of thermal radiation. That is significantly greater than the 1000 W/m^2 solar insolation at ground level (ie, after absorption and scattering as it passes through the atmosphere). (De Saussure's 110 centigrade represents a black body radiation of 1222 W/m^2.)"
But with less than unit emissivity, of course you can get a higher temperature than the insolation. Still, on a good day, insolation can be much higher than 1000 W/m^2. These results are much too anecdotal and the factors which result in a final temperature equilibrium too unknown, such as emissivity, the albedo of the collecting box, what the actual insolation was, etc. The results as they are are extremely close to simple direct heating with hot-air trapping.
"Because the individual photons from sunlight come from the Sun's surface, in principle it would be possible to heat a surface to the temperature of the Sun's surface with no violation of the 2nd law. In practise, we can never achieve perfect efficiency and so that is not possible. Never the less, solar concentrators can achieve temperatures in excess of 3,200 centigrade despite being subject to the same thermodynamic limits."
That is done by concentrating the incoming solar input from a large collecting area and focussing it into a much smaller absorption area. Nothing to do with the greenhouse effect or backradiation/radiation trapping.
" the temperature rises to the point at which the incident heat is exactly balanced by the dissipated heat"
The incident heat is of course given only by the sun. This is why in those experiments you reference, a higher temperature than the solar input was not actually really observed.
Indeed, an empirical test should be done on these matters, accounting for all variables. As it is, aside from the red-herring of solar concentrators (i.e. magnifying glasses, focusing mirrors, etc), there are no numbers which have been presented which show higher-than-insolation temperatures being acheived by passive means.
"Never-the-less, the known facts for de Saussure's hotboxes show with very high probability that the radiant insulation is the most important factor were multiple panels prevent carrying heat of by conduction through a single glass panel."
Indeed, the glass lids prevent the convection of hot air and replacement of cool air from elsewhere.
As a matter of logic, if you have a more complex model created based upon the suppositions induced from a simpler erroneous model, it doesn't save the more complex model. Creating more complex models looking for a radiative back-heating/trapping effect does not prove a radiative back-heating/trapping effect. Besides, when doing more proper physics and science and accounting for the other real phenomena at work, since the supposed back-radiation/trapping is not the only thing occuring, N2 and O2 are already heat trappers due to their low emissivity, and latent heat from liquid and vaporous water already store and release heat at the surface as well. Thus, any argument which posits radiation trapping/back-radiation as the cause of surface temperature must be discarded outright, for pretending to do everything which it manifestly doesn't.
In the argument above with the red and green areas in the plot, the red curve assumes a perfect blackbody of emission at 286K. The surface probably doesn't emit like a perfect blackbody, but more importantly, the surface temperature is not actually 286K - the surface temperature is not actually known at all. The 286K only corresponds to the air-temperature at 1.5m from a haphazardly distributed set of measurement stations on land. We don't actually know what the actual surface temperature is. Thus, the arguments presented there, while quite good and the attempt at proper science is good, is ultimately based on supposition and "if we assumes", etc.
Joe, you have a serious penchant for strawmen. We know there's downwelling longwave radiation because it has been directly measured from surface and has been found to fit pretty well with theory/model-based expectations.
JPostma @47:
1) You have not shown that the simple model fails, ie, that it incorrectly predicts the situation it describes. You have only pointed out that it is too simplistic (flat surface, globally averages insolation, only on layer). Therefore you cannot infer that the more complex model which does not have those oversimplifications fails. To do so is to, yet again, pull your dishonest strawman argument of "refuting" the greenhouse effect by pointing out that an oversimplified model is oversimplified while studiously ignoring the more complex models that also show the greenhouse effect.
2) N2 and O2 are not trappers of radiant heat. More importantly, and more directly, with a detailed model of all energy transfers and relevant latent heats (as in a GCM), removing just the well mixed greenhouse gases increases the upward longwave radiation at the top of the atmosphere and reduces surface temperature. That is, if you include all the relevant physics within computational capacity, greenhouse gases modulate surface temperature by modulating upward TOA IR radiation. This is the third time you have ignored this simple fact. It may be that the model is wrong, but it is not shown to be wrong by only criticizing the single layer model. In fact, by retaining your straw man focus you make clearer and clearer the dishonest nature of your argument.
3) We do in fact know what the global mean surface temperature is to a very good approximation (+/- 0.1 C). More importantly, we know the surface temperature was at various points of observations when comparisons were made between model and observed TOA upward IR radiation (see first panel):
4)
Actually, comparing the upward radiation for 299.7 K at 0 km altitude on modtran (as used in generating the red and green figure) shows the model to have an assumed surface emissivity of 0.9123. If we compare that to the known emissivities of varios surfaces we see that that is a significant underestimate of normal surface emissivities - ie, the model understates the size of the greenhouse effect (graph, and others, from Science of Doom):
5)
I think it is plane to any reader that I am the one actually presenting evidence here. You are the one falling all over yourself to thoughtlessly dismiss that evidence without giving any consideration to what it in fact means.
JPostma @46:
1)
If you mean emissivity across all bands of the spectrum, then no you cannot. For more interesting, however, is the case were you mean near perfect emissivity in visible light, but very low emissivity for IR radiation. In that case, yes you can get higher temperatures than insolation - but the principle by which you do so is that of the greenhouse effect. It turns out that you believe the greenhouse effect after all. At least, you believe it when the context is sufficiently obscure that people will probably not notice the inconsistency of your view with your main thesis.
2)
Show me the evidence!
Remember that to account for the phenomenon, you have to show insolation 20% higher than 1000 W/m^2. To see how difficult that is, here are the cloud free hourly insolations at Albequque on the summer solistice (ie, when the Sun is closest to overhead at noon):
Note that the best values are found with 2-axis tracking, ie, with a mechanism that keeps the collector pointed directly at the Sun through the entire day. Further, note that the Albaquque is at 35 degrees North, which compares to the 34 degrees south of Cape Town where John Herschel made his observations.
3)
First, written reporst by de Saussure and John Hershel (both eminent experimental scientists of their day) do not count as "anecdotal evidence".
Second, as to unknown factors, you are happy to quote botantical greenhouses as evidence despite a far greater number of unknown factors, including a known factor that they maximize glass surface area, and hence cooling by conduction through the glass surface, without any qualms. Your sudden concern for precission is very one sided.
Third, the facts about de Saussure's hot boxs were quoted in direct refutation of your claim that such hot boxes could not increase warmth above that of incident sunlight. In fact, they can, and demonstrably can. Regardless of the specific mechanism, your claim is shown to be false. The true claim is that such mechanisms (and no mechanism) can raise temperatures above the temperature of the energy source, ie, the Sun. But as nobody claims the greenhouse effect can, or does heat the Earth's surface to a temperature equivalent to that of the Sun's surface, that is irrelevant to the discussion.
4)
First, solar concentrators are not a red herring. If you think so, you have misunderstood the 2nd law of thermodynamics.
Second, observations by two of the preeminent experimental scientists of their time have shown temperatures in solar hot boxes sufficient to emit greater energy at source than is recieve by incident radiation on the device. That is only possible because that temperature is less than the temperature of the incident photons, and because the energy leaving the device equals the energy entering the device. But it is possible, and has been observed, regardless of how much you want to ignore the data.