Guest post by Ira Glickstein
The Atmospheric “greenhouse effect” has been analogized to a blanket that insulates the Sun-warmed Earth and slows the rate of heat transmission, thus increasing mean temperatures above what they would be absent “greenhouse gases” (GHGs). Perhaps a better analogy would be an electric blanket that, in addition to its insulating properties, also emits thermal radiation both down and up. A real greenhouse primarily restricts heat escape by preventing convection while the “greenhouse effect” heats the Earth because GHGs absorb outgoing radiative energy and re-emit some of it back towards Earth.
Many thanks to Dave Springer and Jim Folkerts who, in comments to my previous posting Atmospheric Windows, provided links to emission graphs and a textbook “A First Course in Atmospheric Radiation” by Grant Petty, Sundog Publishing Company.
Description of graphic (from bottom to top):
Earth Surface: Warmed by shortwave (~1/2μ) radiation from the Sun, the surface emits upward radiation in the ~7μ, ~10μ, and ~15μ regions of the longwave band. This radiation approximates a smooth “blackbody” curve that peaks at the wavelength corresponding to the surface temperature.
Bottom of the Atmosphere: On its way out to Space, the radiation encounters the Atmosphere, in particular the GHGs, which absorb and re-emit radiation in the ~7μ and ~15μ regions in all directions. Most of the ~10μ radiation is allowed to pass through.
The lower violet/purple curve (adapted from figure 8.1 in Petty and based on measurements from the Tropical Pacific looking UP) indicates how the bottom of the Atmosphere re-emits selected portions back down towards the surface of the Earth. The dashed line represents a “blackbody” curve characteristic of 300ºK (equivalent to 27ºC or 80ºF). Note how the ~7μ and ~15μ regions approximate that curve, while much of the ~10μ region is not re-emitted downward.
“Greenhouse Gases”: The reason for the shape of the downwelling radiation curve is clear when we look at the absorption spectra for the most important GHGs: H2O, H2O, H2O, … H2O, and CO2. (I’ve included multiple H2O’s because water vapor, particularly in the tropical latitudes, is many times more prevalent than carbon dioxide.)
Note that H2O absorbs at up to 100% in the ~7μ region. H2O also absorbs strongly in the ~15μ region, particularly above 20μ, where it reaches 100%. CO2 absorbs at up to 100% in the ~15μ region.
Neither H2O nor CO2 absorb strongly in the ~10μ region.
Since gases tend to re-emit most strongly at the same wavelength region where they absorb, the ~7μ and ~15μ are well-represented, while the ~10μ region is weaker.
Top of the Atmosphere: The upper violet/purple curve (adapted from figure 6.6 in Petty and based on satellite measurements from the Tropical Pacific looking DOWN) indicates how the top of the Atmosphere passes certain portions of radiation from the surface of the Earth out to Space and re-emits selected portions up towards Space. The dashed line represents a “blackbody” curve characteristic of 300ºK. Note that much of the ~10μ region approximates a 295ºK curve while the ~7μ region approximates a cooler 260ºK curve. The ~15μ region is more complicated. Part of it, from about 17μ and up approximates a 260ºK or 270ºK curve, but the region from about 14μ to 17μ has had quite a big bite taken out of it. Note how this bite corresponds roughly with the CO2 absorption spectrum.
What Does This All Mean in Plain Language?
Well, if a piece of blueberry pie has gone missing, and little Johnny has blueberry juice dripping from his mouth and chin, and that is pretty good circumstantial evidence of who took it.
Clearly, the GHGs in the Atmosphere are responsible. H2O has taken its toll in the ~7μ and ~15μ regions, while CO2 has taken its bite in its special part of the ~15μ region. Radiation in the ~10μ region has taken a pretty-much free pass through the Atmosphere.
The top of the Atmosphere curve is mostly due to the lapse rate, where higher levels of the Atmosphere tend to be cooler. The ~10μ region is warmer because it is a view of the surface radiation of the Earth through an almost transparent window. The ~7μ and 15μ regions are cooler because they are radiated from closer to the top of the Atmosphere. The CO2 bite portion of the curve is still cooler because CO2 tends to be better represented at higher altitudes than H2O which is more prevalent towards the bottom.
That is a good explanation, as far as it goes. However, it seems there is something else going on. The ~7μ and ~15μ radiation emitted from the bottom of the Atmosphere is absorbed by the Earth, further warming it, and the Earth, approximating a “blackbody”, re-emits them at a variety of wavelengths, including ~10μ. This additional ~10μ radiation gets a nearly free pass through the Atmosphere and heads out towards Space, which explains why it is better represented in the top of the Atmosphere curve. In addition, some of the radiation due to collisions of energized H2O and CO2 molecules with each other and the N2 (nitrogen), O2 (oxygen) and trace gases, may produce radiation in the ~10μ region which similarly makes its way out to Space without being re-absorbed.
There is less ~15μ radiation emitted from the top of the Atmosphere than entered it from the bottom because some of the ~15μ radiation is transformed into ~10μ radiation during the process of absorption and re-emission by GHGs in the atmosphere and longwave radiation absorbed and re-emitted by the surface of the Earth.
Source Material
My graphic is adapted from two curves from Petty. For clearer presentation, I smoothed them and flipped them horizontally, so wavelength would increase from left to right, as in the diagrams in my previous topics in this series. (Physical Analogy and Atmospheric Windows.)
Here they are in their original form, where the inverse of wavelength (called “wavenumber”) increases from left to right.
Source for the upper section of my graphic.
Top of the Atmosphere from Satellite Over Tropical Pacific.
[Caption from Petty: Fig. 6.6: Example of an actual infrared emission spectrum observed by the Nimbus 4 satellite over a point in the tropical Pacific Ocean. Dashed curves represent blackbody radiances at the indicated temperatures in Kelvin. (IRIS data courtesy of the Goddard EOS Distributed Active Archive Center (DAAC) and instrument team leader Dr. Rudolf A. Hanel.)]
Source for the lower section of my graphic.
Bottom of the Atmosphere from Surface of Tropical Pacific (and, lower curve, from Alaska).
[Caption from Petty: Fig. 8.1 Two examples of measured atmospheric emission spectra as seen from ground level looking up. Planck function curves corresponding to the approximate surface temperature in each case are superimposed (dashed lines). (Data courtesy of Robert Knutson, Space Science and Engineering Center, University of Wisconsin-Madison.)]
The figures originally cited by Dave Springer and Tim Folkerts are based on measurements taken in the Arctic, where there is far less water vapor in the Atmosphere.
[Fig. 8.2 from Petty] (a) Top of the Atmosphere from 20km and (b) Bottom of the Atmosphere from surface in the Arctic. Note that this is similar to the Tropical Pacific, at temperatures that are about 30ºK to 40ºK cooler. The CO2 bite is more well-defined. Also, the bite in the 9.5μ to 10μ area is more apparent. That bite is due to O2 and O3 absorption spectra.
Concluding Comments
This and my previous two postings in this series Physical Analogy and Atmospheric Windows address ONLY the radiative exchange of energy. Other aspects that control the temperature range at the surface of the Earth are at least as important and they include convection (winds, storms, etc.) and precipitation (clouds, rain, snow, etc.) that transfer a great deal of energy from the surface to the higher levels of the Atmosphere.
For those who may have missed my previous posting, here is my Sunlight Energy In = Thermal Energy Out animated graphic that depicts the Atmospheric “greenhouse effect” process in a simlified form.
I plan to do a subsequent posting that looks into the violet and blue boxes in the above graphic and provides insight into the process the photons and molecules go through.
I am sure WUWT readers will find issues with my Emissions Spectra description and graphics. I encourage each of you to make comments, all of which I will read, and some to which I will respond, most likely learning a great deal from you in the process. However, please consider that the main point of this posting, like the previous ones in this series, is to give insight to those WUWT readers, who, like Einstein (and me :^) need a graphic visual before they understand and really accept any mathematical abstraction.
Domenic:
Wow…That was written by one of the co-authors of “Slaying the Sky Dragon”?!? That’s really embarrassing. If I were an AGW skeptic, I would be running as fast as possible to disassociate myself from that book and anyone remotely involved with it! The fact that people like you are actually endorsing such scientific nonsense guarantees that you will continue not to be taken seriously by any serious scientists.
And, you demonstrate that by posting a bunch of pseudoscientific nonsense?!? Let me give you a hint…If you actually want to convert serious scientists to your point-of-view, you would be much better off being a little more discerning in what arguments you choose to embrace. Stick with defending arguments for low climate sensitivity; they also may be pretty poor (e.g., as has recently been demonstrated regarding some of Roy Spencer’s work: http://arthur.shumwaysmith.com/life/content/roy_spencers_six_trillion_degree_warming ) but at least they aren’t patently ridiculous!
For Oliver Ramsay and others who are saying that there is violation of the Second Law of Thermodynamics in the atmospheric greenhouse effect: Show us specifically where said violation occurs using any precise correct statement of the 2nd Law and anything from the full-blown line-by-line radiation calculations to any sort of simple quantitative model of the greenhouse effect (such as the simple shell model that Willis Eschenbach posted about once here on WUWT).
Hint: You won’t be able to do it because in fact none of these descriptions violate the Second Law.
When I teach my students about the Second Law in a few weeks, I will tell them what I always tells them: that the Second Law is a double-edged sword. On the one hand, it is a powerful tool that can easily cut through pseudoscientific nonsense (such as claims of perpetual motion machines). On the other hand, like any powerful tool, it can also be abused to actually spread pseudoscientific nonsense as when incorrect claims are made by creationists that evolution violates the 2nd Law or incorrect claims are made by AGW skeptics that the greenhouse effect violates the 2nd Law.
davidmhoffer says:
Even though David Hoffer and I disagree strongly on the seriousness of AGW, I agree with him that if we are going to debate scientific issues, one might as well debate issues that are still open to real scientific debate (such as the magnitude of feedback effects and hence of the climate sensitivity) than to waste time with claims that are scientifically-ridiculous, such as claims that the greenhouse effect violates the 2nd Law or that humans are not responsible for the rise in atmospheric CO2 levels over the last couple hundred years. Arguing these things may seem fun and may be able to convince some members of the general public but it is only going to further marginalize you in the scientific community … and that is where the scientific debate ultimately matters.
@wayne ( http://wattsupwiththat.com/2011/03/10/visualizing-the-greenhouse-effect-emission-spectra/#comment-618875 ): Okay…Now, I think I understand what you are saying. However, it doesn’t prove what you seem to think it does.
So, for example, if you model the atmospheric greenhouse effect by two shells that pass solar radiation but are blackbodies (perfect absorbers) for longwave radiation then, yes, radiation that is radiated from the outer shell back toward the surface of the earth will be intercepted and absorbed by the inner shell rather than passing down to the earth’s surface. However, if you are hoping that this will somehow negate the atmospheric greenhouse effect, you will be disappointed. In fact, such a simplified model is easy to solve exactly and will have a temperature at the earth’s surface that is higher than the temperature in absence of the shells by a factor of the 4th root of 3. [In general, the model with N blackbody shells has a surface temperature that is higher by a factor of the 4th root of (N+1) from the no-greenhouse case of 0 shells.]
A more realistic model would have “graybody” rather than “blackbody” shells and solving it is a bit more complicated, but the basic structure of the result doesn’t change…i.e., a stronger IR-absorbing atmosphere leads to a higher surface temperature.
Phil says
……….. so far no-one has answered the question, bear in mind what I asked was “What on earth is the ‘quality’ of radiation?”, the simple answer is that there is no such thing!………..
Whats this then ?
Thermodynamic Availability of Solar Radiation
by RH EDGERTON – 1983 – Cited by 2 – Related articles
In the evaluation of second law efficiencies of solar energy converters, a determination must be made of the …. spectral energy flux per unit area per unit frequency in determining the quality of the radiation.
pubs.acs.org/doi/abs/10.1021/bk-1983-0235.ch019
@ur momisugly davidmhoffer
Well, this time I got your attention.
But you’re still not noticing that, time and time again, commenters are acknowledging that energy is radiated from cooler things towards hotter things and that it is absorbed by the hotter things.
It’s what happens after that that’s in dispute.
Radiation and heat are not synonyms for one another. When visible light falls upon a slab of basalt heating occurs, but that’s not the case with chloroplasts. Photosynthesis isn’t about heating CO2 and boiling water.
The back-radiation explanation always seems to end with “…and that heats the surface.”
It’s not actually the surface temperature that we measure. It’s the air above the surface. When we do measure the surface temperature, we find that it varies enormously over distances of inches.
Another thing that is repeatedly recognized is that IR radiation from the surface is absorbed by CO2 and does serve to heat the adjacent N2 and O2.
If you’re irritated by my ridiculous igloo scenario, you will have an idea of how it is to be constantly told “…it’s just basic Physics”.
Climate is an abstract concept that arises from human observation of weather.
Weather is the interactions of all the fluid parts of our planet. It’s more than “basic”.
wayne says:
March 11, 2011 at 9:39 pm
“That brings to mind the one case where I have always considered back-radiation literally, and not merely figuratively, real and proper; that is the case when low clouds are actually at a higher temperature that the surface, warmed from condensation. It does happen, but may be somewhat rare.”
Yes, the problem is that so many things can happen in the atmosfeer. But this is in a much later stage as what I was strictly talking about, and that is the solid surface where LWR is converted in IR and heat, and what will happen in the very next thinkable layer so a micro distance. So this is at the heart of the radiative problem, the source of GHG theory.
Where LWR hits the ocean it gets more complicated with the latent heat escaping and GHG theorie does’nt even want to burn there fingers here. So yes, in the real world we have the atmosfeer with latent heat, presure, lapse rate, clouds etc and al kinds of changes in time that creates temperature differences everywhere on earth. But GHG theorie solely uses radiation budgets and says it’s equal to heat and uses averages only.
So one can only counter the GHG theorie by following their radiation assumptions, and starting from the very first instant where this should start.
“Speaking in terms of individual photons as is common in these discussions, this is the very case where there would be more photons beaming down back to the surface than leaving from the surface traveling upward, literally heat moving downward and warming it. True back-radiation. Still don’t like that term, but since that what it is called, I will continue to use it. This is really just normal radiative warming from warm clouds.”
Well, as long as it is higher in temperature (kinetic energy) it will flow to any lower temperature (up or above) by conduction/convection. Only the portion of water in it will also radiate IR. So this would indeed heat the lower levels towards earth.
Bryan says:
March 12, 2011 at 6:36 am
“Whats this then ?
Thermodynamic Availability of Solar Radiation
by RH EDGERTON – 1983”
Is’nt it great Brian what you can find digging in the solar thermodynamics?
Ira
In addition to the many other comments above, I’m afraid I cannot agree with your analysis that “the “greenhouse effect” heats the Earth because GHGs absorb outgoing radiative energy and re-emit some of it back towards Earth.” I’m making an assumption that you mean the downward radiative energy will hit the earth. I’m basing this assumption on the fact that you only acknowledge that some energy transfer from GHG to N2 and O2. See where you state:
“In addition, some of the radiation due to collisions of energized H2O and CO2 molecules with each other and the N2 (nitrogen), O2 (oxygen) and trace gases, may produce radiation in the ~10μ region which similarly makes its way out to Space without being re-absorbed.”
If I am incorrect, please accept my apology.
In my view, the common “hit the earth” conclusion over-relies on an unsupported assumption that radiative transfer is “super dominate” transfer mechanism in the atmosphere. It appears just as likely that most radiative energy coming from the ground and subsequently absorbed by GHG is simply transferred to other atmosphere gases, liquid vapors, and ice by ordinary thermo/physical processes.
Both Einstein and Neils Bohr provided a fairly sound basis for evaluating the predicted behavior of photons and simple gases. (For those interested, a good entry level description can be found in Chapter 12 of the text book “Fundaments of Phononics” by Bahaa E. Saleh and Malvin Teich; John Wiley & Sons, 1991 edition). I have read two papers that used the Bohr/Einstein approach both of which call into question AGW theory due to AGW failure to fully account for thermal transfer due to light/mass interaction (i.e. the saturation effect). Courtesy would demand that I provide the titles and the authors names to the papers from which I am referring. However, I have lost the papers and cannot recall the authors names. To this extent I apologize.
In my mind, one of the most troubling aspects of the “back radiation” argument is that it ignores two serous statistical thermodynamic problems: 1) that the average direction of re-emission energy flow resulting from a photon hitting a GHG molecule is zero, and 2) that radiative re-emission is not the only avenue with which the GHG molecule can be dissipate the energy.
With respect to the directional issue, only if one is very close to the earth can one claim any “back radiation” will be remitted by the earth’s surface. The higher one goes the more likely any back radiation will simply the absorbed by the gases below.
With respect to energy conversion, one must consider the statistical probability that the GHG molecules energy will be simply be absorbed by molecule using alternate energy states (for example by evaporation, sublimation, or adiabatic cooling via expansion). Or that the energy will be transferred to another molecule by kinetic impact – prior to any radiative re-emission event. This leads directly to evaluation of simple gases via Einstein’s A and B coefficients and Neils Bohr related evaluations referred to above.
I see another problem with the “back radiation” causes heating claim. Radiative transfer to a body with mass (with the transfer represented by Q), is and always has been, a subset of thermal heat transfer. One cannot ignore that both thermal and radiative transfer are the result of photon exchange at the molecular level – real photons (light) for radiative transfer and virtual photons for heat or thermal exchange. Thermal and radiative transfer are, in fact, subsets of the same phenomena.
Consequently, in my view, the thermal gradient resulting from radiative transfer with gases are analogues to a thermal gradient in purely thermal transfers. Even in thermal transfer, molecules are hitting and transferring energy “up-stream” to the hot side; but, the net transfer is to the cold side. Radiative transfer is no different. Back radiation is not causing any additional warming – it is just a natural part of the temperature gradient observed when dealing with molecules or other bodies in bulk. I recognize there is the complication that not all gases will re-radiate at the same wave lengths nor at the same rate for a given temperature. Never-the-less the temperature gradient issue remains when considering bulk heat transfer wither by thermal or radiative means.
Further, trying to rationalize the concept of “back radiation” as an “augmenter” of GHG warming leads one down the slippery slope of assuming that atmospheric radiative transfer is a reversible adiabatic process (i.e., is solely radiative and involves no transfer of heat – or assumes ant thermal transfer effects are minimal).
Simply put, one cannot have an adiabatic process (where heat transferred (Q) is equal to zero) and simultaneously have radiative heat transfer (where Q is a fixed value). A fundamental tenet of thermodynamic analysis of both thermal and radiative transfer is that the transfers can be described by the formula Q = hr*A*(Ts1 – Ts2); where Q = the heat transferred, hr is the radiative heat transfer coefficient (a function of temperature that can be derived from the Stefan-Boltzmann equation in the case of radiative transfer), A is the area, and Ts1 & Ts2 are the respective temperatures of given bodies. (See the text “Momentum, Heat, and Mass Transfer”; by Bennet and Myers, McGraw-Hill, 1974, 2nd edition; pages 309 & 435).
The overused “adiabatic” radiative assumption by the AGW community, via the back radiation argument, leads to a non-physical situation where one has no energy exchange between molecules “heated” by radiative transfer. In other words, in AGW climate science, a heated CO2 molecule is not expected to hit a nearby colder molecule – resulting in a transfer of energy.
Clearly we don’t live in a thermodynamic world where an isolated volume of gas at a given temperature consists of many molecules all at different temperatures – none of which collide. In short, the entire concept violates the statistical basis upon which the 2nd law of thermodynamics is based – from the perspective of two gas molecules in close proximity existing at different temperatures and not exchanging “heat” thru kinetic impact both up and down stream of the temperature gradient.
While the simplifying adiabatic “science” assumptions are useful in metrological prediction (where one has measured temperature gradients as a starting point for weather prediction); it is not at all surprising that this “simplified” approach starts to break down in a matter of days. Nor is it surprising that AWG “climate scientist” cannot accurately predict the tropical temperature profile with altitude.
Simply put, from my view, their highly “simplified” non-physical thermodynamic model quickly falls apart with time – as the impacts of conduction, convection, evaporation, condensation and other effects overwhelm the simplified model.
I have no problem with you analysis regarding the effect at the boundary points between the earth/atmosphere and atmosphere/space; but I feel your electric blanket analogy is too simplistic and provides an inaccurate description what is likely happening within the atmosphere.
I’ve struggled to provide a better analogy. Unfortunately I can’t come up with one simply because I don’t feel we understand atmospheric thermodynamics well enough to draw firm conclusions. Having no bases for a conclusion one cannot draw an analogy.
Given the considerable uncertainty and level of disagreement in this area, might the better course be to simply acknowledge is considerable agreement that GHGs can deliver IR energy to the atmosphere; but, there is considerable debate about how the heat is dissipated within the atmosphere?
Kindest Regards, Kforestcat (D. A. Kelly)
Oliver Ramsey;
If you’re irritated by my ridiculous igloo scenario, you will have an idea of how it is to be constantly told “…it’s just basic Physics”.>>>
Well now I am irritated again. Because time and again my explanations have started with “if there were no other factors”. I’ve repeatedly made it clear that CO2 in the atmosphere is a far more complicated matter than the behaviour of CO2 in isolation. Further, my response was in regard to cold things being able to radiate energy to warm things.
What purpose does it serve to ridicule a my answer about one thing, and then when your criticism gets slashed to ribbons for being a total piece of garbage, you hit back with “well now you know I feel when” and complain about yet another thing that I never even said?
If your contention is that I’m wrong, then provide a cogent response.
If your contention is that any physical process in isolation may not be the same in a real world scenario, I’ll say Oliver is right.
But I will say this about “basic physics”. If you have any hope of ever understanding climate, then get the basic physics right first. Then move to how the various pieces interact.
How does a car work? Answer; You put your key in the ignition and turn until it starts. Then you put it in gear and step on the gas to make it go forward. You use the steering wheel to change direction. That whole answer is correct and useless. I just told you how to operate it, not how it works. You haven’t a clue how it works. Open the hood and look inside. You now know what it looks like under the hood, but you have no idea how it works.
If you want to understand how it works, you’ll have to break it down into its major operating components. Drive train, suspension, steering, ignition system. You still won’t know how it works, but you’ll be able to see what each of those pieces does in relation to the others. Then you can take each of them and break them down into their operating components.
Eventually you have an entire car reduced to pieces.
I’m standing there with a piston, explaining that the explosion of the fuel drives the piston downward and you interrupt me with:
“Don’t be stupid, something that gets pushed straight down can’t make tires rotate in a circle. I’m tired of having the basic physics explained to me, these are all just little pieces lying on the floor, a car is much more complicated than that”
Yes it is Oliver. But the reason that the car works is that every nut, bolt, piston, ring, axle, crank, every single part was designed by someone who knew the basic physics of that part in isolation to the nth degree. Anyone who thinks that a car can be designed and produced without relying on the basic physics of each and every component to be correct is welcome to try.
The reason car companies build test models is to see if the basic physics of the parts in combination produces a different result than anticipated.
What value there is in complaining that a piston in vertical motion can’t cause something to rotate and besides, it is so much more complicated than just that, is beyond me.
Yes Oliver, it is more complicated. That doesn’t change the fact that pistons go up and down and they drive tires that go around and around, it doesn’t change the fact that cold things radiate energy that is absorbed by warm things but also absorbe more energy from the warm thing itself, it doesn’t change the fact that CO2 absorbs certain wavelengths of LW and re-emitts them in a random direction resulting in the exact same equilibrium transmission of energy to space, but with a different temperature curve from TOA to surface that, IN ISOLATION OF ALL OTHER FACTORS, would be warmer than if the CO2 was not there.
How does CO2 work in combination with all the other factors? I don’t know. But if you are going to build a working model of a car without understanding how the vertical motion of a piston gets translated into rotational motion, the best your model will ever accomplish is to mimic the operating characteristics of the real car. The moment the real car encounters a situation that your model can’t mimic because it isn’t based on the actual physics of how the car really works, your model will fail.
Sound like any climate models you may have heard about? The ones that backcast just fine because they mimic the observed behaviour of the climate without understanding all the elements, and then blow it entirely when used to forecast? As in all of them? Not one model in IPCC AR4 got it even close, they had to “average” 20 models to get a result closer than any single model could produce. Which is exactly what one would expect from models that mimic over all behaviour (operating characteristics) without understanding the basic physics of each component.
I’m going for a drive now. I won’t be worried about how a piston going up and down makes my tires spin. I can observe that it is true. But somewhere in the process there was design expertise that was involved that knew precisely how. If there wasn’t…well I expect then when I start the car, put it in gear, and step on the gas, some rather unexpected may happen.
kforestcat says:
Hans says:
Where are you guys getting this stuff? You know, it might help to actually read a book on planetary climate and the modeling of the greenhouse effect before actually telling us what such analysis does and does not include. If we put you in a time warp and sent you back a half century or so, SOME of your objections might actually be valid; however, the science has advanced since then. I recommend reading something like “Principles of Planetary Climate” by Ray Pierrehumbert that I am struggling through right now. (It is well-written, but by no means an easy read.)
Some of your statements are just bizarre and I don’t know where they are coming from. The models consider only radiation budgets and no transfer of heat by convection? Really? The models assume no transfer of energy between the CO2 molecules and other molecules in the atmosphere by collisions? Really? The models don’t take into account that radiation from one level can be absorbed by the levels below it before reaching the ground? Really?
I am reminded of the quote often attributed to Will Rogers or Mark Twain: “It’s not what he doesn’t know that scares me. It is what he does know that just ain’t so!”
Joel Shore wrote:
“When I teach my students about the Second Law in a few weeks…”
and
“I recommend reading something like “Principles of Planetary Climate” by Ray Pierrehumbert that I am struggling through right now. (It is well-written, but by no means an easy read.)”
A person who struggles with introductory texts like Ray’s book should not teach and must change profession.
Lots of verbiage on heat magically moving from cold to hot which misses one very simple point. It is true that all objects radiate. It is also true that CO2 will radiate even at -50C. It is also true that the earth at a much higher temperature will also radiate. In fact since the earth is at a much higher temperature than atmospheric CO2, the net heat flux is from the earth to the the upper atmosphere. In other words, the earth’s heat radiation will tend to increase the temperature of the CO2 since more heat is radiated from the earth to the CO2 than from the CO2 to the earth. Note also that the mass of the earth is a trillion times greater than the mass of CO2 and as such has substantially more heat capacity.
Al Tekhasski says:
Great…So, since you are such a high and mighty expert on it, perhaps you should give a tutorial on the book or on the subject in general for the WUWT audience. There are clearly a lot of people here who can learn a lot from that book.
I will add that my profession is teaching physics, not climate science. And, it was perhaps a little bit strong of me to say I was “struggling”. However, when I read “for pleasure” I tend to be a little bit intellectually lazy about really working through stuff in detail…and while I found that such a reading approach was fine for the 1st 3 chapters, the 4th chapter did have some sections where I really needed to put more focus in than what I was initially expecting to have to do. My point was basically just to make clear that Ray’s book is not a “light read” like reading a blog post and would require a fair investment of time and energy to read and appreciate.
Dear Joel Shore
Per your comment at March 12, 2011 at 11:01 am where you state:
“You know, it might help to actually read a book on planetary climate and the modeling of the greenhouse effect before actually telling us what such analysis does and does not include.”
In point of fact I have both read and analyzed both papers and textbooks on GHG theory as well as followed discussion regarding these “science” details via “The Science of Doom” and other blog sites. Furthermore I have a Chemical Engineering degree and roughly 30 years of professional engineering experience as well as experience in managing R&D teams with multi PHDs working for me. So I don’t “struggle” with issues like thermodynamics/mass transfer/heat transfer/fluid dynamics/basic elements of quantum theory/reaction kinetics. Nor do I struggle with science “controversy” or the presentation of controversial science results. Nor do I worry too much about training students. I do worry about the roughly $5.0-7.5 billion in capital equipment investment decisions that I am personlly responsible for. There is a difference between teaching and serious engineering/science.
In any event I am not “telling” you what “such analysis does and does not include”. I am providing my opinion based on my professional judgment, experience and training. One may accept or reject that view as one chooses. Please note that none of my comments above or below are intended to be an attack on you or sarcasm.
Regards you comment:
“If we put you in a time warp and sent you back a half century or so, SOME of your objections might actually be valid; however, the science has advanced since then.”
No, I’m sorry, but my training wasn’t “half a century ago” and the the basic laws of thermodynamics and fluid flow have not “advanced” much since yesterday. In any event, the application of thermodynamic/fluid theory to complex natural systems is an inherently risky venture; simply because the analysis requires the application of simplifying assumptions whereas inherently complex natural systems, like the Earth’s atmosphere, follows multiple inter-related non-liner chaotic paths – paths that defy our present ability understand, predict, or model. (Noting some planetary system are easier to analyze than others.)
When one does consider attempts to couple man-made GHG theory to thermodynamic/fluid theory one has to look at the underlying simplifying assumptions used in the SPECIFIC analysis in a particular paper, text book, or model. Where I have looked those assumptions, in detail, I have repeated found the core equations were commonly derived by assuming the absence of convective effect and/or minimizing those effects or used underlying assumptions that render non-physical results.
Furthermore, as Mr. Willis and other have repeated demonstrated, many of the models take a step further by casting out any relationship to thermo and fluid theory. Modeling, well… the opinion of the modeler.
Regards your comment:
“The models consider only radiation budgets and no transfer of heat by convection? Really? The models assume no transfer of energy between the CO2 molecules and other molecules in the atmosphere by collisions? Really? The models don’t take into account that radiation from one level can be absorbed by the levels below it before reaching the ground? Really?”
My reply it that depends on the individual model. Some do attempt to take convection into account – but not necessarily in a rigorous manner. Others state they do, but, when you look at the underlining equations one finds that the effects of convection are removed or minimized by simplifying assumptions.
Do some models “assume transfer” of energy to other molecules. Some do; but certainly not rigorously – usually by an opinion based fudge factor – this is a notoriously complex subject in Earths atmospheric where we have condensing/non-condensing gases as well as complex mixtures of GHG and non-GHG gases. In other cases, the equations used were derived from data produced for utility boilers. However, these results are based on the behavior of gas when surrounded by metal walls which serve as close black bodies. The radiate behavior of gas mixtures well away from solid surfaces is not necessarily identical and has not been thoroughly studied. Furthermore, even the models used to design or optimize boilers produce “crap shoot” results – this in situations where the details of the underlying conditions are intimately known.
Some models don’t take into “radiation from one level can be absorbed by the levels below it”? In point of fact many vertical GHG models do – or at least attempt to. However, many make the assumption that virtually all of the energy transfer is via radiative transfer. Often because the models can’t handle heat transfer/fluid dynamic issues along the horizontal axis.
Models are only as good as the assumptions. Use of simplifying assumptions to facilitate scientific analysis, or to render modeling results more efficiently, is a time honored tradition in the scientific/engineering community. Particularly when one is looking for clues of POSSIBLE behavior. However, one never assumes any equation or model are accurate representation of fact UNLESS THE RESULTS CAN BE MEASURED AND VALIDATED.
In my opinion, our current models of Earth’s atmosphere don’t come close to being complete or accurate representations of atmosphere.
Finally, I have not read “Principles of Planetary Climate” by Ray Pierrehumbert. However, I will put it on my reading list.
Regards, Kforestcat (D. A. Kelly).
Before getting too overheated about Dr. Pierrehumbert’s book, I would ask you to consider which of the following quotes are the most monumentally stupid.
Distributed uniformly over the mass of the planet the absorbed energy would raise the Earth’s temperature to nearly 800,000K after a billion years, if Earth had no way of getting rid of it.
—Raymond T. Pierrehumbert
People think about geothermal energy—when they think about it at all—in terms of the hot water bubbling up in some places, but two kilometers or so down in most places there are these incredibly hot rocks, ‘cause the interior of the earth is extremely hot, several million degrees, and the crust of the earth is hot…
—Albert Arnold Gore
Joel Shore says:
March 12, 2011 at 5:41 am
“When I teach my students about the Second Law in a few weeks, I will tell them what I always tells them: that the Second Law is a double-edged sword. On the one hand, it is a powerful tool that can easily cut through pseudoscientific nonsense (such as claims of perpetual motion machines). On the other hand, like any powerful tool, it can also be abused to actually spread pseudoscientific nonsense as when incorrect claims are made by creationists that evolution violates the 2nd Law or incorrect claims are made by AGW skeptics that the greenhouse effect violates the 2nd Law.”
The laws of thermodynamics appear to apply to information as well energy in that:
1. conservation of information – information cannot be created or destroyed it may only change form
2. entropy – information cannot spontaneously increase by natural processes
The stock answer for how the information contained in DNA managed to get there is that the earth is not a closed system and energy from the sun drove the decrease in entropy (increase in information).
Sounds reasonable but it seems a bit of a leap to exchange energy and information willy nilly like that. There’s a deep relationship between energy and information and particularly with the second law. See link below for more information (pun intended):
http://en.wikipedia.org/wiki/Entropy_in_thermodynamics_and_information_theory
The creationist argument is that the decrease in information entropy requires intelligent agency. I’m not sure why science doesn’t consider intelligent agency to be a natural process given most scientists believe the only known intelligent agency in the universe (rational man) arose via natural processes.
Anyhow one might ask oneself if the Library of Congress could be created by the sun driving natural processes – that the sun became less ordered so that the Library of Congress could become more ordered and thus not be in violation of the second law. Ya think? That seems a bit on the ridiculous side to me.
One should at least understand what “the creationists” are actually saying before dismissing it.
Just sayin…
My friend Granville Sewell, a math professor at the University of Texas (PhD in math from Purdue) wrote a wonderful paper 10 years ago:
Can ANYTHING Happen in an Open System?
I mean it’s ridiculous to me on the face of it that an open system doesn’t mean anything can happen. Sewell goes about explaining why it can’t from a mathematician’s point of view. It’s well worth reading. In the interest of giving perspective from “the other side of the debate” to your students you might point them to it. The author’s creds as a math professor are pretty damn good and very likely of higher pedigree than yours so it should be a real treat for them.
Hans says:
March 12, 2011 at 9:34 am
wayne says:
March 11, 2011 at 9:39 pm
“That brings to mind the one case where I have always considered back-radiation literally, and not merely figuratively, real and proper; that is the case when low clouds are actually at a higher temperature that the surface, warmed from condensation. It does happen, but may be somewhat rare.”
Yes, the problem is that so many things can happen in the atmosfeer. But this is in a much later stage as what I was strictly talking about, and that is the solid surface where LWR is converted in IR and heat, and what will happen in the very next thinkable layer so a micro distance. So this is at the heart of the radiative problem, the source of GHG theory.
—–
Thanks Hans for the clarity. I see now, just at the surface interface. I was carrying it to the a more global inter-atmosphere effects and outside of your example.
Anthony Zeeman says:
March 12, 2011 at 1:15 pm
Quite true. I might point out though that rocks are a rather good insulator and very little of the mass of the earth is heated by the sun. The earth’s internal energy (heat of formation, radioactive decay) leaks out at around a milliwatt per square meter but due to the insulation provided by the crust most of what it started with billions of years ago is still there and molten hot. The moon on the other hand lost most its initial heat and is solid to the core with a constant year-round temperature of -23C beginning at about 1 meter deep. Presumably the earth would be the same temperature as the moon if it weren’t for greenhouse gases. Actually the earth would be quite a bit colder because the moon (contrary to what you’d think just by looking at it) has a very low albedo about the same as weathered asphalt at 16%. If the earth had no greenhouse gases it would ostensibly be covered in ice & snow with an albedo over 80%.
I agree with everything you wrote David. The welcome voice of reason. THANKS!
However, I would have said “CAGW” rather than “AGW” because, strictly speaking, I (and I believe you do as well) accept that GHGs are partially responsible for the fact the average temperature of the globe is warmer than it would be absent those GHGs (the “GW” part) and that the human contribution to GHGs, due to our burning of unprecedented quantities of fossil fuels in recent decades is partially responsible for the warming we have experienced (the “A” part).
Thus, a proper science-based argument is, yes, there is AGW, but it is dwarfed by natural processes and cycles over which humans have absolutely no control. Whatever minor warming and CO2 rise we are responsible for is probably beneficial for human civilization. There is not now and never has been any “tipping point” or “runaway” risk of CAGW.
Phil. says:
March 11, 2011 at 10:22 pm
“What on earth is the ‘quality’ of radiation?”
Which is nothing to do with the radiation, you can’t tell me what the ‘quality’ of 5μm radiation is for example.”
It is related to it’s temperature of origin, radiation energy density in J/m^3. So not surprising related to the Stefan-Boltzmann equation (SB times 4/c).
For the LWR coming from 5777 K resulting in 0.84 J/m^3
For the SWR from earth surface at 255 K in 0.32 * 10^-5 J/m^3
Ira Glickstein;
However, I would have said “CAGW” rather than “AGW” because, strictly speaking, I (and I believe you do as well) accept that GHGs are partially responsible for the fact the average temperature of the globe is warmer than it would be absent those GHGs (the “GW” part) and that the human contribution to GHGs, due to our burning of unprecedented quantities of fossil fuels in recent decades is partially responsible for the warming we have experienced (the “A” part).>>>
Sorry, but I think AGW is the right term. I accept the AGW theory in terms of what a GHG does in isolation, which is warm the planet surface. But the order of magnitude is so teeny that it is just a rounding error next to natural variability. And when someone says AGW they generaly in my experience include things like “water vapour feedback” in addition to GHG’s themselves, and that certainly is a concept riddled with holes. Even those warmists who have backed down from the “C” word still predict ludicrous effects such as increased severe weather and decreased rainfall despite sound science and actual observation suggesting the opposite is true.
Its like claiming that if I steal $100.00 from Bill Gates, he will be so distraught that he may have a heart attack or else hunt me down and have me flogged. Everyone starts arguing about how distraught he may or may not be, and I’m just thinking… he’d even notice?
CO2 is a GHG. The planet hasn’t noticed.
Joel Shore wrote:
“… such a reading approach was fine for the 1st 3 chapters, the 4th chapter did have some sections where I really needed to put more focus in than what I was initially expecting to have to do. My point was basically just to make clear that Ray’s book is not a “light read” like reading a blog post and would require a fair investment of time and energy to read and appreciate.”
If you had to put “more focus” into effects of GH gases with more realistic spectrum (like Ray’s “oobleck”, or real line spectra), how do you expect “to focus” on real issues with global circulation of atmosphere, where (in Chapter 9) he has a very special introduction into fluid dynamics, right in spherical coordinates, right with condensible substance transport, but recommends to a reader with no corresponding background to skip his musings? Where he talks about “mass streamfunction” without bothering to define what the heck it is? (maybe the final version has it, than I apologize). Skipping over the entire turbulence issues does not make the understanding of planetary atmospheres any better either. Good luck to you in your time investment.
Ira
I have never believed in an any ‘runaway’ risk of CAGW. Many years ago I could see that was a fiction made up by people who do not understand radiational heat transfer and thermodynamics.
But, up until a month or so ago, I used to think the same thing as you do, that there was some minor AGW.
However, as I poured through all the data, the one place I kept returning to is the interior Antarctic data. As a scientist and engineer, I could not disregard the importance of that data. It is the most pristine data on earth. It is even superior to satellite data (satellite data is loaded with assumptions).
The Amundsen-Scott and Vostok record from 1957 to date requires no assumptions.
The CO2 data from there confirms the rise in CO2.
The temperature data, however, shows flat to decreasing temperature over the period.
To me, as a scientist and engineer, the most pristine data ALWAYS rules. Ergo, even an assumption that there is a tiny amount of AGW is COMPLETELY UNSUPPORTED by the best possible data available.
That is what I have learned over the past month or so as I delved deeply into any possible reality of AGW.
The touchy feely stuff is fun to speculate on. But that is all that it is. A figment of the imagination not correlating with reality.
@ur momisugly davidmhoffer
It’s feeling a lot like the movie Groundhog Day.
You come up with a parable or an analogy or an anecdote or lecture on the virtues of reductionism complete with rocker-arm assemblies and imaginary conversations with the idiot that you take me to be, then I or someone else responds and you only address the flippant parts and insist that cold things radiate at hot things.
WE KNOW THAT!
The dispute has been about whether cold things HEAT hot things.
You don’t appear to have grasped that and so, repeatedly bemoan the obtuseness of people that don’t believe that all things radiate in random direction.
WE DO BELIEVE THAT!
Tell us about how the absorption of those photons raises the average kinetic energy of the absorbing matter.
Tell me about the role played by heat in photosynthesis if you’re making the case that heat and energy and radiation are synonyms for one another.
I don’t quarrel with the existence of a greenhouse effect, I don’t even have a problem with the name. I suspect I am even more charitably disposed towards climate scientists than you are.
I even understand that, at the scale of a small number of molecules, vibrational modes yield to translational.
I agree that a thermometer outside your igloo can show a lower temperature than one inside (it could be higher, too), but I don’t believe that when you take a thermometer out of your pocket and put it in your igloo the temperature shown will increase.
If it all just makes you angry, then why bother?
——————
@ur momisugly Joel
I have never said that the greenhouse effect, as I understand it, defies the Second Law, the version of which I offer is from Flanders and Swann c. 1960
Heat won’t pass from a coola to a hotta,
You can try it if you’d like but you’d far betta notta
‘Cos the cold in the coola will get hotta as a rula
And that’s a physical law.
I don’t know if it would be more palatable to you if you imagined Feynman enunciating it.
Dave Springer
….”Presumably the earth would be the same temperature as the moon if it weren’t for greenhouse gases. Actually the earth would be quite a bit colder because the moon (contrary to what you’d think just by looking at it) has a very low albedo about the same as weathered asphalt at 16%. If the earth had no greenhouse gases it would ostensibly be covered in ice & snow with an albedo over 80%.”…..
I just dont buy this artificial construct.
The Surface of the Earth is 70% water. Why ignore this massive heat store?
Active volcanoes are also under the sea.
So no chance of snowball earth.
The real test of the IPCC position is what would happen to the Earths climate if CO2 did not radiate in the Infra Red.
I suggest there would be very little difference to the present climate and if anything perhaps a little warmer.