Guest Post by Ira Glickstein
This series began with a mechanical analogy for the Atmospheric “Greenhouse Effect” and progressed a bit more deeply into Atmospheric Windows and Emission Spectra. In this posting, we consider the interaction between air molecules, including Nitrogen (N2), Oxygen (O2), Water Vapor (H2O) and Carbon Dioxide (CO2), with Photons of various wavelengths. This may help us visualize how energy, in the form of Photons radiated by the Sun and the Surface of the Earth, is absorbed and re-emited by Atmospheric molecules. 
DESCRIPTION OF THE GRAPHIC
The animated graphic has eight frames, as indicated by the counter in the lower right corner. Molecules are symbolized by letter pairs or triplets and Photons by ovals and arrows. The view is of a small portion of the cloud-free Atmosphere. (Thanks to WUWT commenter davidmhoffer for some of the ideas incorporated in this graphic.)
- During the daytime, Solar energy enters the Atmosphere in the form of Photons at wavelengths from about 0.1μ (micron – millionth of a meter) to 4μ, which is called “shortwave” radiation and is represented as ~1/2μ and symbolized as orange ovals. Most of this energy gets a free pass through the cloud-free Atmosphere. It continues down to the Surface of the Earth where some is reflected back by light areas (not shown in the animation) and where most is absorbed and warms the Surface.
- Since Earth’s temperature is well above absolute zero, both day and night, the Surface radiates Photons in all directions with the energy distributed approximately according to a “blackbody” at a given temperature. This energy is in the form of Photons at wavelengths from about 4μ to 50μ, which is called “longwave” radiation and is represented as ~7μ, ~10μ, and ~15μ and symbolized as violet, light blue, and purple ovals, respectively. The primary “greenhouse” gases (GHG) are Water Vapor (H2O) and Carbon Dioxide (CO2). The ~7μ Photon is absorbed by an H2O molecule because Water Vapor has an absorption peak in that region, the ~10μ Photon gets a free pass because neither H2O nor CO2 absorb strongly in that region, and one of the 15μ Photons gets absorbed by an H2O molecule while the other gets absorbed by a CO2 molecule because these gases have absorption peaks in that region.
- The absorbed Photons raise the energy level of their respective molecules (symbolized by red outlines).
- The energized molecules re-emit the Photons in random directions, some upwards, some downwards, and some sideways. Some of the re-emitted Photons make their way out to Space and their energy is lost there, others back down to the Surface where their energy is absorbed, further heating the Earth, and others travel through the Atmosphere for a random distance until they encounter another GHG molecule.
- This frame and the next two illustrate another way Photons are emitted, namely due to collisions between energized GHG molecules and other air molecules. As in frame (2) the Surface radiates Photons in all directions and various wavelengths.
- The Photons cause the GHG molecules to become energized and they speed up and collide with other gas molecules, energizing them. NOTE: In a gas, the molecules are in constant motion, moving in random directions at different speeds, colliding and bouncing off one another, etc. Indeed the “temperature” of a gas is something like the average speed of the molecules. In this animation, the gas molecules are fixed in position because it would be too confusing if they were all shown moving and because the speed of the Photons is so much greater than the speed of the molecules that they hardly move in the time indicated.
- The energized air molecules emit radiation at various wavelengths and in random directions, some upwards, some downwards, and some sideways. Some of the re-emitted Photons make their way out to Space and their energy is lost there, others back down to the Surface where their energy is absorbed, further heating the Earth, and others travel through the Atmosphere for a random distance until they encounter another GHG molecule.
- Having emitted the energy, the molecules cool down.
DISCUSSION
As in the other postings in this series, only radiation effects are considered because they are the key to understanding the Atmospheric “Greenhouse Effect”. I recognize that other effects are as important, and perhaps more so, in the overall heat balance of the Earth. These include clouds which reflect much of the Sun’s radiation back out to Space, and which, due to negative feedback, counteract Global Warming. Other effects include convection (wind, thunderstorms, …), precipitation (rain, snow) and conduction that are responsible for transferring energy from the Surface to the Atmosphere. It is also important to note that the Atmospheric “Greenhouse Effect” and a physical greenhouse are similar in that they both limit the rate of thermal energy flowing out of the system, but the mechanisms by which heat is retained are different. A greenhouse works primarily by preventing absorbed heat from leaving the structure through convection, i.e. sensible heat transport. The greenhouse effect heats the earth because greenhouse gases absorb outgoing radiative energy and re-emit some of it back towards earth.
That said, how does this visualization help us understand the issue of “CO2 sensitivity” which is the additional warming of the Earth Surface due to an increase in atmospheric CO2? Well, given a greater density of CO2 (and H2O) molecules in the air, there is a greater chance that a given photon will get absorbed. Stated differently, a given photon will travel a shorter distance, on average, before being absorbed by a GHG molecule and be re-emitted in a random direction, including downwards towards the Surface. That will result in more energy being recycled back to the Surface, increasing average temperatures a bit.
Smokey says:
When I see you making statements like this, I am reminded of what Mohandas Gandhi is purported to have said when he was asked (upon a visit to England, I believe), “What do you think of Western civilization?” and he replied, “I think it would be a very good idea.”
I recommend you try actually modeling what you preach and you could do so by no longer embracing almost every piece of nonsense that supports what you want to believe and discounting everything that doesn’t. And, not making malicious charges about respected scientists that you can not back up when called to do so (but still continuing to repeat them). I’d like to see you actually set some high standards for yourself rather than just for other people. Or is that too much to ask?
Joel Shore says:
April 7, 2011 at 4:16 am
Hans says:
I just wanted a simple confirmation that by the same principle the sun must get warmer.
“No,we do not know that, for the reasons I have stated in my previous posts if you actually bothered to read and comprehend them.”
No need to complicate things, it’s all just about temperatures isn’t it.
1. GHG’s heat up earth surface so the sun receives more radiation back (using Stefan-Boltzmann) and heats up.
2. GHG’s reduce the temperature difference between sun and earth surface, if we want the same power flow the sun has to heat up (power varies with T sun^4 – T earth^4).
” Now it can’t stop here because we learned from the iron in the box that a higher temperature of (the first appearing) restriction (now earth) heats the source (the sun). If not delta T sun-earth would now get smaller than before and the heat flowing from the sun would be less.
Statements like this make me wonder if you are comprehending anything that we tell you. Yes, it can stop there because I have described to you the final steady-state state that the system converges to.”
You didn’t talk about the total system, but just isolate the earth. The system begins with the sun and ends in space. GHG’s form an extra layer for radiation coming from the sun.
Like N equal layers reduce radiation to 1/(N+1) of the original flow, so will the radiation from the sun be partly reduced by a partial extra GHG layer. To get more radiation through the system the temperature of the sun must rise because space is fixed at 3K.
Joel Shore says:
“I recommend you try actually modeling what you preach…”
For the umpteenth time: scientific skeptics have nothing to prove. But the Joel Shores of this world keep trying to shift the onus onto skeptics, to prove a negative. Joel Shore has the scientific method exactly backwards: it is his job to provide convincing evidence of anthropogenic runaway global warming. So far, he has failed.
So he constantly tries to re-formulate the scientific method into post-normal ‘science’, to try and require skeptics to prove something. The common thread that runs through the entire alarmist crowd is their perverting, ignoring and/or misprepresenting the scientific method.
If the CO2=CAGW conjecture is not falsifiable, it is no more than a conjecture; an opinion – no matter how fervently Joel Shore wishes it was a testable hypothesis.
Smokey:
Shorter Smokey: “Personal responsibility, integrity, and honesty are for you other suckers, not for me. I can link and repeat debunked nonsense from now until the cows come home and make accusations against people that I can’t support because I [ridiculously] call myself a skeptic, which gives me a free pass to throw as much nonsense around as I like and hope a little bit of the mud sticks.”
Sorry, Smokey, but these qualities are for everybody. And, in fact, it is on “skeptics” to step up and actually come up with something coherent to say rather than just to throw out a lot of nonsense like you do. It is no more the responsibility for us to prove AGW to you than it is for me to prove evolution to someone who doesn’t believe it. It is part of the accepted science of the field now. If skeptics want to change that, they have got some work to do…and the first would be to try to rid their ranks of people who don’t want to discuss science in a serious manner but instead want to make a lot of nonsense arguments that tell serious scientists, “These people are just jesters, not people making serious scientific arguments.”
Hans says:
You can’t make things simpler than they actually are. I explained some of the complications in previous posts. If you can’t intelligently engage in these arguments, then there is little that I can do.
I’ve explained to you that the situation is different both because of geometry and because of the fact that most of the sun’s radiation is at wavelengths that the GHGs do not absorb. But, even if we ignored those facts, it still wouldn’t change the fact that you would still have a steady-state solution…not a diverging series. In fact, you would probably find that the additional temperature the sun would need to account for this issue would be something like 10^(-20) deg C.
Look, you can throw out objections from now til eternity. If someone wants to believe in a 7000 year old earth badly enough, they can always find rationalizations to do so. If you want to not believe in the greenhouse effect, you can always find rationalizations to do so. Just don’t expect us to think you are making this decision on the basis of science because you are not.
Joel Shore says:
April 9, 2011 at 7:29 am
Smokey:
“For the umpteenth time: scientific skeptics have nothing to prove. But the Joel Shores of this world keep trying to shift the onus onto skeptics, to prove a negative.”
Shorter Smokey: “Personal responsibility, integrity, and honesty are for you other suckers, not for me. I can link and repeat debunked nonsense from now until the cows come home and make accusations against people that I can’t support because I [ridiculously] call myself a skeptic, which gives me a free pass to throw as much nonsense around as I like and hope a little bit of the mud sticks.”
As Smokey has been told multiple times, a null hypothesis must be falsifiable which the assertion of ‘natural variability’ is not, whereas the recycling of IR by CO2 is falsifiable therefore yields a more appropriate null hypothesis.
Joel Shore says:
Shorter Smokey: “Personal responsibility, integrity, honesty…” & blah, bla, etc.
# # #
Putting fabricated quotes purporting to be my comments is the only way Joel Shore can try to make any headway. Talking about ‘integrity’ and ‘honesty’ is clearly psychological projection on Joel’s part, and Phil is simply carrying his water.
Joel Shore and Phil still fail to understand the null hypothesis, which comprises the parameters of the climate over the Holocene, and states that the same parameters, temperatures, cycles, trends, etc., will continue. It is easily falsifiable: simply show that those temperatures, trends, cycles and parameters have been exceeded, either on the high or low side. Michael Mann tried to show that with his bogus Hokey Stick, but as we know that has been completely debunked. In fact, the null hypothesis remains unfalsified.
The alternative hypothesis [CO2=CAGW] that is tested against the observed reality of the null has failed to falsify the null hypothesis – which means that the alternative hypothesis fails. Rising CO2 has made no testable, measurable difference to global temperatures, trends, or cycles. In fact, the current climate is especially benign, being far from the Holocene extremes.
None of the runaway global warming predictions have come to pass, and nothing indicating any climate catastrophe or global damage from CO2 is anywhere on the horizon. Thus, the nonsense continually spouted about these fictitious non-events necessitates an immediate end to the $billions wasted on “climate studies” each year.
Smokey says:
I don’t think anybody would mistake what I wrote with the preamble “Shorter Smokey” for being your words. What it represents is a more accurate description of what you actually (and seem to feel in terms of personal responsibility) than what you say. (Although you are pretty direct in stating that you and those who espouse your views essentially have no responsibility, a rather strange point-of-view for a conservative to have if you ask me. Like I said, I guess in your mind personal responsibility is a quality that is only important for other people to have.) You are just making up imaginary transgressions on my part in the hopes of distracting others from the lack of integrity that you have shown consistently here in the past.
“Natural cycles” is a non-explanation, only a small step better than saying “God did it”. Do you mean natural forcings or do you mean climate internal variability? Since we don’t have all that good data on the (relatively small) natural forcings during the Holocene, it is actually still challenging to separate the two.
As I noted to Hans, you can believe what you want to believe…and none of your statements regarding the actual state of the science are falsifiable since they are just your opinions. Being that they are in direct contradiction to the opinions of most of the scientists in the field, almost all of the scientific societies that we rely on to adjudicate in such matters, and my own personal opinion of the science (which, unlike yours, is based on at least some actual scientific understanding), I frankly would wonder why anybody would take your opinion at all seriously (unless you are saying what they already want to believe).
and
It seems to me you are arguing past each other.
For example, I do not believe a scientific case has been made, or can be made for Catastrophic CAGW, or any kind of disaster due to human burning of fossil fuels and changes in land use.
On the other hand, I believe an absolutely solid scientific case has been made for the role of certain gases in the Atmosphere, primarily H2O and CO2, in raising the mean temperature of the Earth from what it would be if the Atmosphere was pure N2. To the extent that humans have been burning fossil fuels in unprecedented quantities, which has caused some significant percentage of the measured rise in CO2 levels in the Atmosphere, and to the extent that our land use has reduced the albedo of the Earth, I believe an absolutely solid scientific case has been made for AGW (Anthropomorphic Global Warming). That is, human activities have raised the mean temperature of the Earth above what it would have been if only Natural Cycles and Processes had been at work.
Given the above, the only scientific question is: How much has AGW raised mean temperatures above what they would have been if only Natural Cycles had been at work?
Bottom line:
1) A scientist can accept AGW without embracing any kind of Catastrophic CAGW.
2) It is unscientific to to Disbelieve in AGW. DAGW is as incorrect as CAGW.
RJ, I found what I believe is the original source of your teacher/student analogy. It is from Claes Johnson’s chapter in Slaying the Sky Dragon available here as a .pdf file, see the 4th page of the .pdf, which is labeled “167 “.
A simple refutation of the analogy is that good teachers do learn from their students. Of course, if the teacher is competent, the net flow of knowledge, at least in the domain of knowledge in which the teacher is competent, will be from teacher to students.
However a more thoughtful and serious critique is that Energy/Matter is conserved and cannot be created nor destroyed. For Energy to flow from the Sun to Earth, or from the Earth to the Atmosphere, or Atmosphere to Earth, the amount of Energy in the former must decrease exactly as much as the amount of Energy in the latter.
In that respect, Energy is like money. If I give you $100, your net worth account increases and mine decreases by that amount. If you give $50 back to me, your account decreases and mine increases, again by the exact same amount.
Knowledge, on the other hand may be multiplied without limit. The teacher may pass his or her knowledge on to as many students as you’d like, and the amount of knowledge the teacher has is not diminished one whit. Indeed, if a student happens to have an insight and share it with the teacher, that may increase the teacher’s knowledge!
The business about “cut-off frequency” in Johnson’s paragraph quoted above, has to do with his strange idea that high frequency radiation (short wavelength, i.e., UV, visual, near-IR) cannot be absorbed by a blackbody that is at a lower temperature than the source. Now I understand the nonsence in this thread that claims that only low frequency radiation (long wavelength, i.e., far-IR) has a heating effect.
I’d appreciate it if some of those in this thread who are more knowledgeable (and patient) than I am would read the chapter linked above and comment further. As an electrical engineer, I find the analogies to cut-off frequencies and feedback in audio systems and audio amplifiers to be completely misplaced. It also seems to me his ideas about quanta are wrong, but I am no expert in that area.
Ira
“Bottom line:
1) A scientist can accept AGW without embracing any kind of Catastrophic CAGW.
2) It is unscientific to to Disbelieve in AGW. DAGW is as incorrect as CAGW.”
Unscientific. ????? Are you resorting to name calling again?
Surely science should always be open to new ideas even if they challenge established theories. The back radiation theory is not a fact. It has been challenged and quite effectively on this thread and in various articles and books.
“The net result is that a warm blackbody can heat a cold blackbody, but not the other way around. A teacher can teach a student but not the other way around. The hot Sun heats the colder Earth, but the Earth does not heat the Sun. A warm Earth surface can heat a cold atmospheric layer, but a cold atmosphere cannot heat a warm Earth surface. A blackbody is heated only by frequencies which it cannot emit, but has to store as heat energy.”
Thanks. And this surely is a worthwhile debate. Can a colder body heat a warmer one by back radiation. Or is Claes correct
If the back radiation theory is correct. Then surely this can be proved as I have noted above. By putting a heat source in O2. And then the same source in CO2. And comparing the temperatures. Back radiation should make the heat source in CO2 hotter. Or is there some reason why this can not be done.
RJ says:
The laws for radiative transfer are so well-tested that, yes, it is completely perverse and unscientific to disbelieve them in the lack of very compelling evidence to the contrary. Although it may be true that nothing is absolutely provable in science, science does advance. Do you think, for example, it is scientific to seriously entertain the fact that the Earth is only 6000 years old at this point?
And, the point is that before you challenge some very well-established laws of science, you have to understand them and the evidence for them. Challenging them out of ignorance is in fact quite unscientific. It is abundantly clear to us that you have never solved an equation in radiative transfer or even read through a serious exposition where these equations are solved for simple systems. How could you possibly be in the position to say that a well-established law of science is wrong when you have so little understanding yourself?
Ira Glickstein says:
Actually, it is kind of weird because it is never really clear what he is arguing; he makes lots of implications about things but doesn’t really come right out and say what his thesis is about exactly where he disagrees with the established science.
A couple comments: He says, “The mere naming of something does not bring it into physical existence.” Unfortunately, that statement works both ways. Yes, the content of the physics is contained in the equations, not really how one chooses to name the terms. The problem for him is that the content of the equation is that when an object is in a lower temperature surroundings, then the flow of heat from the object to the surroundings is less when the surroundings are warmer than when they are colder. It doesn’t matter if you ever use the term “back radiation” or not (although the fact that you can measure the radiation, certainly does imply the surroundings are really radiating…and the laws of physics tell us that they have to). You get the same numerical answers whether you use that term or not.
And, he talks the usual nonsense about back-radiation meaning everything blows up…which basically just means he doesn’t understand the difference between divergent and convergent series (or that he hopes his audience doesn’t).
As I’ve said before, the only interesting question is whether someone who is clearly smart and knowledgeable to understand the mathematics behind radiative transfer in quite a bit of detail as Claes is can really delude himself into believing the nonsense that he writes or whether he is actively trying to deceive people who are less knowledgeable.
As I have noted, there is a disturbing common thread in the work of Claes and that of others like Gerlich and Tscheuschner, which seems to be to “snow” readers with lots of mathematics (most, if not all of which, is actually correct) and then tack on nonsense interpretations of it. I mean, do they really believe that the average reader of “Slayer” is going to be able to follow the mathematical exposition? (We can’t even seem to get the people doubting the greenhouse effect in this thread to go through the simplest sort of mathematical models of it.) So, what is the point of writing down all of this mathematics that nobody is really arguing about (and that actually disproves your thesis if you give it a modicum of thought) and that few readers are likely to follow anyway, except if your purpose is to try to make the nonsense conclusions that you claim follow from it (when they don’t) more convincing for readers who don’t have the knowledge to recognize when they are being “snowed” by mathematics that they don’t understand?
Ira;
Well said.
Joel Shore;
A fine summation. I haven’t read G&T in a very long time, I will revisit it. Beyond that, everything you said I 100% endorse and applaud you for saying it.
“(although the fact that you can measure the radiation, certainly does imply the surroundings are really radiating…and the laws of physics tell us that they have to). ”
Does this comment cover in part this point or not. (I don’t understand this comment but I am very interested by this whole debate.)
http://www.slayingtheskydragon.com/en/blog/102-climate-follies-encore
“Lord: “Back radiation can be simply demonstrated by pointing a simple infrared detector at the underside of a cloud. Try it.”
Chorus: “My IR detector only cost $60! Simple! Agreed! Agreed!”
Slayer: “Clouds do not absorb and re-radiate heat back to Earth. Clouds add THERMAL MASS which takes longer to heat and cool. Warmists ‘support’ this false hypothesis with IR thermometer readings, but the IR readings of a hot Barbie is the same from any distance; ENERGY is not. Your $60 REMOTE thermometer is not measuring the radiant energy you are receiving, it is measuring the resonance of the Barbie.”
And is there an answer to my question above. If a heat source is enclosed in O2 and then CO2. Would it achieve a greater temperature in CO2. Or is this a silly question?
RJ says:
“The back radiation theory is not a fact. It has been challenged and quite effectively on this thread and in various articles and books.”
First, RJ, define “back-radiation theory”. Do you mean that the idea that the earth absorbs IR radiation emitted from the sky is not a fact? There are innumerable measurements of IR radiation from the sky. There are innumerable measurements of the IR spectra of H2O and CO2 showing that they should create the observed spectra. There are innumerable experiments on the IR absorption of various types of soil/rock/vegetation/water. The quantum theory of molecular vibration & rotation predicts that CO2 & H2O should emit IR radiation (but that N2 & O2 should not).
WHICH SPECIFIC IDEA ABOVE DO YOU THINKS HAS BEEN EFFECTIVELY CHALLENGED?
Or do you mean something else? Perhaps you think certain wavelengths of IR radiation avoid getting absorbed by the ground — which specific wavelengths would those be? Or perhaps you are challenging the 1st law of thermodynamics — where does the energy come from to keep the ground warm if IR radiation from the sky is not part of the energy?
In fact, the poorly named “back radiation theory” is about as close to “fact” as any theory.
“Can a colder body heat a warmer one by back radiation. ”
DEFINE “HEAT”. Then we can move forward. Give a precise mathematical and verbal definition of what “heat” means to you. How would you define “to heat” and “to warm”? Are they identical? If you can’t do that, then how can you possibly think you you are in a position to question established science?
“If the back radiation theory is correct. Then surely this can be proved as I have noted above. By putting a heat source in O2. And then the same source in CO2. And comparing the temperatures. Back radiation should make the heat source in CO2 hotter. Or is there some reason why this can not be done.”
To a scientist or engineer, this sounds a lot like “If our understanding of insulation is correct, then a wall of styrofoam should keep a house warmer than a wall of aluminum. Surely this could be proved by building a house out of styrofoam and a house out of aluminum and comparing the temperatures inside them. Is there some reason this has not been done?”.
Not every permutation of every law gets tested in every possible scenario. The thermal conductivity of Styrofoam and aluminum are known, so anyone with a basic knowledge of physics/engineering/heat flow could make a pretty good estimate of how much extra energy it would take to heat the Al house on a given winter day. There is no need to actually BUILD the houses to confirm this fact. The mere fact heat flow has been measured across standard sheets of the two materials will suffice. Similarly, the IR properties of O2 & CO2 are known. There is no need to build the actual overn to confirm this.
I must admit part of me wants to do exactly the experiment outlined by RJ, just to be able to say “here is the SPECIFIC experiment you requested, and it shows you are wrong.” However, there are many practical problems — a few that come to mind include:
* you would need several meters of gas to get significant absorption of IR
* you would need to limit IR from other sources, so the walls of the container should be as cool as possible,
* CO2 & O2 have different specific heats
* Conduction & convection would need to be minimized.
I must admit part of me wants to do exactly the experiment outlined by RJ, just to be able to say “here is the SPECIFIC experiment you requested, and it shows you are wrong.” However, there are many practical problems — a few that come to mind include:
* you would need several meters of gas to get significant absorption of IR
* you would need to limit IR from other sources, so the walls of the container should be as cool as possible,
* CO2 & O2 have different specific heats
* Conduction & convection would need to be minimized.
Tim
Thanks for this reply. I’m not an expert but I can not understand why a simple experiment has not (or can not) be done as noted above. And why not just have a vacuum then a layer of CO2 or O2. And as long as IR from other sources did not vary would it matter. CO2 should make a significant difference compared to O2 or say air.
And by back radiation I mean that energy / heat leaves the earth as radiation and the same energy returns due to GHGs and then further heats the earth. (By another 33 degrees C)
I’m confused as a non scientists that something like this is not a lot more straight forward. It’s a huge claim regarding CO2 and water vapour (that it absorbs and reemits infrared radiation and then further heats the earth than would occur if only the sunlight was absorbed) that surely should be easily testable in some way.
Tim Folkerts says:
April 10, 2011 at 1:12 pm
RJ says:
“The back radiation theory is not a fact. It has been challenged and quite effectively on this thread and in various articles and books.”
First, RJ, define “back-radiation theory”. Do you mean that the idea that the earth absorbs IR radiation emitted from the sky is not a fact? There are innumerable measurements of IR radiation from the sky. There are innumerable measurements of the IR spectra of H2O and CO2 showing that they should create the observed spectra. There are innumerable experiments on the IR absorption of various types of soil/rock/vegetation/water. The quantum theory of molecular vibration & rotation predicts that CO2 & H2O should emit IR radiation (but that N2 & O2 should not).
And of course spectroscopic measurements confirm the predictions for CO2, H2O vs N2, O2.
The idea that one sees here and elsewhere that the idea of ‘back radiation’ is somehow a construct of ‘AGW’ is of course nonsense, it is a basic tenet of radiational heat transfer as anyone who reads a textbook on the subject will find out (H C Hottell’s for example). Calculations of this nature are carried out routinely by engineers but the ‘climate skeptics’ don’t want to deal with that.
RJ;
You want an experiment?
Here it is.
http://www.john-daly.com/artifact.htm
Now as you read through the gory details keep in mind:
1. Heinz Hug went to great lengths to create an artificial atmosphere with 2.6% water vapour, and 357 ppm of CO2, measured IR absorption and then repeated at 714 ppm CO2 (exactly double)
2. His MEASUREMENTS showed an absorption of 0.054 w/m2 due to doubling of CO2, and concluded that this was 1/80th of the estimate being used by IPCC etc.
Point 1 – You can argue magnitude if you would like, but you can’t argue the results he got which is that CO2 absorbed and reradiated. 0.054 instead of the estimated 3.7, but IT STILL HAPPENED.
Point 2 – If you will read the criticisms of this paper in the link at the top, you will find a logical explanation for 0.054 instead of 3.7 w/m2. In Hug’s experiment the atmosphere has less water vapour with altitude. As a consequence the efficiency of CO2 rises as water vapour falls. If the experiment were done with decreasing amounts of water vapour to simulate the atmosphere, the collective result would have been 3.7 w/m2.
So there you have it. Even ignoring the next step of simulating decreasing water vapour, there you have an actual experiment showing that CO2 does in fact absorb and reradiate.
I meant in above in Hug’s experiment the artificial atmosphere is 2.6% water vapour at all times which is not what happens in the real atmosphere. In the real atmosphere water vapour falls with altitude. Since water vapour and CO2 have overlapping absorption ranges, CO2 becomes more significant with altitude as it no longer has to compete with water vapour for the available photons to absorb.
“It’s a huge claim regarding CO2 and water vapour … that surely should be easily testable in some way.”
It IS testable in many ways and HAS been tested in many ways. There is no single experiment that will confirm all of the details of “back-radiation”. But there are 1,000’s of experiments performed my scientists and 1,000’s of practical devices built by engineers that confirm these ideas. It is only a huge claim to those who don’t understand.
“I’m confused as a non scientists that …”
It is confusing that fast moving clocks record time differently than stationary clocks. Or that the universe is getting bigger. Or that a single electron can go thru two different slits. Or that something as simple as a double pendulum can exhibit unpredictable, chaotic motion.
If you want to be unconfused, you have to understand the ideas yourself! If you admit you are confused, then don’t start with the assumption that something that is confusing is wrong.
“And by back radiation I mean that energy / heat leaves the earth as radiation and the same energy returns due to GHGs and then further heats the earth. ”
So you don’t include energy that comes straight from the sun to the atmosphere (68 W/m^2 in the K&T diagram)? Or the the energy from the earth to the atmosphere from thermals or evaporation/condensation?
The point is that it it all tied in together. The whole diagram is consistent with conservation of energy and the 2nd law of thermodynamics. (There may be a few numbers off a little, but not enough to question the basic science behind the diagram.)
Try this example with money instead of energy.
* I start with $0
* Everyday I get $100 (energy from the sun)
* I spend half of the money I have (the hotter the object, the more it emits)
My balance after getting paid and then after spending the money will be:
100 50
150 75
175 87.5
187.5 93.75
193.75 96.88
196.88 98.44
198.44 99.22
Eventually the balance will be $100 at the start of the day, $200 after getting paid, and $100 after giving away $100. Even though I started with $100, I ended up with more because I saved a bit (especially the first few days)
Now, of the money I spend, I get half of it back. Maybe it is a kick-back. Maybe I spend 1/2 my money at a store, and the store owner pays me to mow his lawn. In any case, I am getting “my own” money back because it is the money I paid him to begin with. The equilibrium condition is “Get $100, pay $100 = steady balance each day”
Now my balance will look like (money after getting paid; money after paying half; money returned as a kick-back)
100 50 25
175 87.5 43.75
231.25 115.63 57.81
273.44 136.72 68.36
305.08 152.54 76.27
328.81 164.4 82.2
346.61 173.3 86.65
359.95 179.98 89.99
369.97 184.98 92.49
377.47 188.74 94.37
383.11 191.55 95.78
387.33 193.66 96.83
390.5 195.25 97.62
392.87 196.44 98.22
394.65 197.33 98.66
395.99 198 99
396.99 198.5 99.25
397.74 198.87 99.44
Now — even thought I am simply getting “my own money back” — I end up with a lot more money — $400 in this case. I will have TWICE as much money each day compared to no kick-backs. The equilibrium condition is “Get $100, pay $200, get $100 back = steady balance each day”
The details, of course, are a bit different, but the concept is the same for the GH effect.
Ira,
You miss my point.
If there is no catastrophic runaway global warming caused by CO2 [and there is zero evidence supporting that conjecture], then the immense public funding spent on CAGW alarmism is not only completely wasted, it is promoting a bogus “carbon” scare among the general population.
If CO2 causes catastrophic global warming, then prove it! Otherwise, admit that the scare is completely overblown, and that what we’re observing is mostly just natural variability.
“If you want to be unconfused, you have to understand the ideas yourself! If you admit you are confused, then don’t start with the assumption that something that is confusing is wrong”
I’m confused that something as simple as the GHG back-radiation theory has not been proved beyond doubt.
For example does the example by DavidM above prove that the heat sources temperature increases. Say in my example above if the heat source was an oil filed heater. Heat the oil to say 30 degrees C. Suspend in a vacuum then an outer layer filed with air. Then replace the air with CO2. Back-radiation should noticeable increase the oils temperature. Then replace with air again and the oils temperature should fall again (I’m not concerned about the temperature of the air or CO2 or the radiation levels leaving the outer container).
If this experiment was done then surely the GHG back-radiation theory would be accepted without question if the oil temperature increased in CO2. The extend of warming in the atmosphere would still be debated by that’s it.
But I’m not a scientist and maybe I’m looking at this with a flawed non science mindset with insufficient understanding.
“So you don’t include energy that comes straight from the sun to the atmosphere (68 W/m^2 in the K&T diagram)? Or the the energy from the earth to the atmosphere from thermals or evaporation/condensation? ”
No.
I don’t have a problem with these parts. It’s just the GHG back-radiation section that I have a big problem with.
And yet AGW seems to be totally built on this theory. That radiation leaves earth and returns to further increase the temperature of earth. And not by a very small amount either.
It covers many unlikely components IMHO
1 That a cold body can heat a warm one. I still have a problem with this
2 That heat or energy leaves earth’s surface as radiation. Why not conduction etc
3 That the amount of water vapour and CO2 is sufficient to cause this amount warming (33 degrees C) to a much bigger earth (a candle heating a huge room type situation) even if energy is returned by AGW back-radiation.
4 It also seems to mean that back-radiation seems to create more energy. That energy leaves earth and interacts with GHGs and more returns. Otherwise just accept it is the sun heating earth not the atmosphere.
But thanks for the input. But I’m still not convinced regarding back-radiation further heating earth. I’m not saying I’m right but just do not know.