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Eclectic at 21:55 PM on 27 November 2024CO2 effect is saturated
CallItAsItIs @770 :-
If I may answer on Scaddenp's behalf ~ I would point out that what you say could have relevance on Mars with a pure CO2 atmosphere (disregarding a trace of nitrogen & argon). But on planet Earth, your explanation clearly fails the reality test.
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CallItAsItIs @769 :-
Well, I give you points for being entertaining !
My cynical streak impels me to the suspicion that you are using AI-generated language to produce a garbled incoherence of "explanations".
Even better is your novel suggestion that atmospheric molecules cannot give or receive energy to/from other atmospheric molecules (why ~ because Second Law of T , of course, eh what, eh ).
And surely only an AI would assert that H2O molecules have no indirect or direct effect or interaction (kinetic or photonic) with nearby N2 , O2 , or CO2 molecules.
Vraiment une tour de force, mon ami. (Does the AI tackle French, as well? )
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CallItAsItIs at 21:01 PM on 27 November 2024CO2 effect is saturated
scaddenp @768
... - if you look at Trenberth diagram you will notice incoming energy flux at earth surface is 161+333 W/m2 (of course balanced by the same outflow), whereas incoming energy flux at TOA is only 341W/m2. These of course are measured values. How does your unconvential view of physics account for this?
I do not address energy balance issues other than those within the atmosphere which apply to the CO2 band saturation issue. I assume a given (but adjustable) intensity value for the 15 micron absorption band at the surface, and see how this radiation is attenuated with respect to altitude. By tuning this intensity value and possibly the absorption factor, we should (hopefully) be able to obtain a balanced energy solution that is also radiometrically correct. From what I have found so far, however, I believe it would be quite at "stretch" to avoid band saturation since we CO2 is such a strong absorber at 15 microns.
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CallItAsItIs at 20:33 PM on 27 November 2024CO2 effect is saturated
Eclectic @767
Why must conservation of energy "hold for each frequency independently of the others" ?
Because when we break down the EMR into the sum of contributions from the different frequencies it contain, we find that each such contribution is incoherent relative to the others. This means that the energy flux of the entire distribution is simply the sum of the energy fluxes from each contribution. Now, if this is unclear to you, please understand that I cannot pack an entire radiometry textbook into this comment space.
And your Demonic suggestion that seems to imply that atmospheric molecules cannot (in bulk) gain energy from neighbouring molecules . . . is another novel idea that requires your explanation.
No, that idea is not so novel since the occurrence you describe would violate the second law of thermodynamics.
And all this time, you have avoided the IR role (and other roles) of H2O molecules.
That's right since I am only addressing the issue of CO2 band saturation and not H2O greenhouse warming which is completely different.
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scaddenp at 18:44 PM on 27 November 2024CO2 effect is saturated
CallItAsItIs - if you look at Trenberth diagram you will notice incoming energy flux at earth surface is 161+333 W/m2 (of course balanced by the same outflow), whereas incoming energy flux at TOA is only 341W/m2. These of course are measured values. How does your unconvential view of physics account for this?
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Eclectic at 18:21 PM on 27 November 2024CO2 effect is saturated
CallItAsItIs @765 ; @766 :-
Each of your "explanations" generates the need for more explanations.
e.g. ~ Why must conservation of energy "hold for each frequency independently of the others" ? [unquote]
[ Even the famous scientific pioneers of the 19th century would be scratching their heads over this novel idea of yours. ]
And your Demonic suggestion that seems to imply that atmospheric molecules cannot (in bulk) gain energy from neighbouring molecules . . . is another novel idea that requires your explanation.
And all this time, you have avoided the IR role (and other roles) of H2O molecules.
And you have not explained why your idea of "TOA" is so very different from that of the mainstream atmospheric physicists.
Yessir, there's much for you to explain ~ to readers and to yourself.
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CallItAsItIs at 16:54 PM on 27 November 2024CO2 effect is saturated
Bob Loblaw @762
The catch is that all CO2 molecules are continually emitting radiation. This represents an energy loss. And they make up for that energy loss by colliding with other molecules (such as N2 and O2) and gaining energy when those molecules have higher energy.
And how do they get this extra energy? — from Maxwell's Demons! (LOL)
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CallItAsItIs at 16:37 PM on 27 November 2024CO2 effect is saturated
Bob Loblaw @764
Come on, Bob! Learn some physics!
What we call sources of energy depends on our system and what we are trying to determine. In the case of the greenhouse effect, we are trying to determine the warming of the atmosphere due to GHGs tapping energy from the terrestrial IR radiation rising from the surface. This means that the upwelling terrestrial IR radiation is the source. The GHGs catch energy in the form of photons from this source, and convert it to kinetic energy of the atmospheric gases (including the GHGs). These GHGs, however, are not sources since they contribute no energy of their own.
The sun also is a source of energy since it puts out IR radiation which is absorbed by the GHGs and converted into thermal energy in the same manner as the terrestrial IR radiation. The atmosphere's primary source of thermal energy, however, is the upwelling terrestrial radiation since IR radiation is more at the "tail-end" of the solar spectrum.
If we are interested in determining the temperature of the "solid" subterranean earth, then the sun becomes our primary source. In this case, the earth absorbs the EMR from the sun which is mostly in the visible spectrum since that is where the peak solar emissions occur. Also, the atmosphere is transparent to visible EMR (ie. light). The down-welling terrestrail radiation from the atmosphere is another a source, but a much weaker one.
Now that we have (hopefully) gotten it straight as to what is meant by sources of energy, let's get back to the problem-at-hand of assessing saturation of the 15 micron absorption band of CO2. In this case, our source of energy is the upwelling terrestrial radiation within this absorption band. Since the contributions to the total upwelling EMR at different frequencies involve different photons, conservation of energy must hold for each frequency independently of the others. This enables us to use the Beer Lambert law to evaluate the attenuation of each frequency component of the upward-bound IR. And, as indicated in previous posts, intensity contributions within the 15 micron band become pretty miniscule at altitudes well below the TOA.
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Bob Loblaw at 11:22 AM on 27 November 2024CO2 effect is saturated
CallItAsItIs:
Since you are really big on making sure we agree on basics and terminology, could you please provide us with your definition of "sources of energy"?
Try to remember the principle of conservation of energy while you are at it.
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Bob Loblaw at 11:19 AM on 27 November 2024CO2 effect is saturated
CallItAsItIs @ 761:
You say:
Convection and conduction are mechanisms for transferring energy. They are not sources of energy.
And that is why the Trenberth diagram uses the title "Global Energy Flows".
It may be news to you, but radiation is also a mechanism for transferring energy. Have you never noticed that radiation travels from one place to another? It does so fairly quickly - as a rough approximation, at the speed of light.
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Bob Loblaw at 11:14 AM on 27 November 2024CO2 effect is saturated
CallitAiItIs @ 760:
Once again, you fail to look at the entire system, and fail to understand what is being said to you.
What Charlie Brown says in 756 is correct. Indeed, his statement that "CO2 molecules collide with N2 and O2 to come to thermal equilibrium (i.e., same temperature)" means exactly the same thing as your statement "CO2 molecule releases the energy it gained from the photon absorption which then becomes kinetic energy of both molecules, thereby raising temperature. "
The catch is that all CO2 molecules are continually emitting radiation. This represents an energy loss. And they make up for that energy loss by colliding with other molecules (such as N2 and O2) and gaining energy when those molecules have higher energy.
The energy transfer via collision between CO2 and other molecules works in both directions, depending on the relative energy level of the individual molecules. (You can't talk about temperature of an individual molecule, as "temperature" is a bulk property of many molecules. Average kinetic energy.)
I have previously pointed you to this blog post at Eli Rabett's, where this is explained well.
Please read some of these additional links you have been pointed to. You continue to embarrass yourself by making elementary errors in physics. Until you unlearn your misconceptions, it is very difficult for you to get an accurate understanding of this subject.
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CallItAsItIs at 11:07 AM on 27 November 2024CO2 effect is saturated
Bob Loblaw @754
Convection and conduction are mechanisms for transferring energy. They are not sources of energy.
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CallItAsItIs at 10:58 AM on 27 November 2024CO2 effect is saturated
Charlie_Brown @756
It works like this: photon is absorbed by CO2. CO2 molecules collide with N2 and O2 to come to thermal equilibrium (i.e., same temperature). CO2 molecule emits photon. The net effect at equilibrium is a pass-through of energy unless there is a change that upsets equilibrium.
Wrong! It works like this: Photon is absorbed by CO2. Energized CO2 molecule collides with N2 or O2. In this collision, CO2 molecule releases the energy it gained from the photon absorption which then becomes kinetic energy of both molecules, thereby raising temperature. At the same time, of course, the CO2 molecule returns to it original state, ready to absorb another photon.
In your explanation, warming of any of the atmospheric gases would not be possible with violating energy conservation.
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Bob Loblaw at 08:16 AM on 27 November 2024CO2 effect is saturated
Oh, and when CO2 (or anything else) "absorbs a photon", it does not store the photon, it just stores the energy. The photon ceases to be. It is no more. It is a "late" photon.
When CO2 (or anything else) emits a photon, it does not get one out of storage. It creates one using energy stored elsewhere in the molecule.
Energy is conserved, but there is no such law as "conservation of photons", as Charlie Brown has already stated in comment 757.
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Bob Loblaw at 08:10 AM on 27 November 2024CO2 effect is saturated
Charlie Brown @ 757:
Minor correction - yes, individual photons have the properties of both wavelength and frequency. Part of the weirdness of the particle/wave duality of light/EM radiation.
The wavelength, frequency, and energy of a photon are all tied together. If it is a 15um photon, that also sets its frequency and energy level. All 15um photons are the same.
A "stream" of photons is not like a stream of water where everything is connected. Even a stream of photons is just a bunch of individual photons passing one at a time past a point in space. When silicon diodes are used as radiation sensors, they are basically "photon counters".
When a higher temperature means more energy emitted at a specific wavelength, it just means "more photons", not "more energy in each photon".
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Charlie_Brown at 04:27 AM on 27 November 2024CO2 effect is saturated
Clarification: Pass-through of photons is more descriptive than pass-through of energy. Photons don't have wavelength so it risks mixing up the concept of electromagnetic radiation as waves or particles. However, they are emitted at a specific frequency so a stream of photons can be described as wavelength. A column of the atmosphere has conservation of energy, not conservation of photons. Radiant energy follows the temperature profile of the atmosphere. Stefan-Boltzmann Law: Intensity = emittance (specific to wavelength) x Stefan Boltzmann constant x absolute temperature to the 4th power.
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Charlie_Brown at 03:04 AM on 27 November 2024CO2 effect is saturated
CallItAsItIs @748,
Since you ask a specific question: Kirchhoff’s Law is absorptance = emittance (at thermal equilibrium). It works like this: photon is absorbed by CO2. CO2 molecules collide with N2 and O2 to come to thermal equilibrium (i.e., same temperature). CO2 molecule emits photon. The net effect at equilibrium is a pass-through of energy unless there is a change that upsets equilibrium.
You emphasize that the 15-micron absorption band (by which I think you mean the approximately 14-16 micron band and not a few 14.9 micron peak lines) absorbs completely within 10 meters of the surface. @725 you say “CO2 can still emit IR radiation (at any wavelength) but can no longer absorb within this band.” @751 the 15 micron absorption band of CO2 is strong enough to pack the thermal radiation from the entire band into a layer at the surface just a few tens of meters thick.” On the other hand, @740 you seem to acknowledge that the spectra showing upward IR within the band are correct, not just at 70 km but also at lower altitudes. If you were consistent, there would be zero intensity for the band because it would have all been absorbed at low altitude. Maybe I give you too much credit there, since your interpretation of the spectra was not correct and you said CO2 can still emit but no longer absorb, so maybe you were not being inconsistent but just do not apply Kirchhoff's Law.
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Bob Loblaw at 00:09 AM on 27 November 2024CO2 effect is saturated
As a followup to my comment at 753, I grabbed the Trenberth diagram from this SkS post, where it is figure 6. The caption for that figure gives the source as this.
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Bob Loblaw at 23:43 PM on 26 November 2024CO2 effect is saturated
...and to respond to CallItAsItIs @ 751, where he says:
The primary mechanism for the sun warming the earth is the absorption of visible light (from the sun) into the solid portion of the earth which then acts as a near blackbody. This blackbody radiator then warms the atmosphere by conduction and convection.
This, and the rest of your comment at 751, is essentially correct. Yet for some strange reason, you completely ignore all this atmospheric heating by conduction and convection when you claim that there is no possible source of energy to drive emission of 15um radiation within the atmosphere. In comment 741 (responding to my comment 732, where I said the atmosphere is a source of IR radiation), you stated:
Are you saying that the atmosphere heats itself!? Wrong! This would violate energy conservation. In order to to heat the atmosphere, we must bring in IR from outside the atmosphere. In the case of greenhouse warming, this is the 288 K IR eminating from the surface of the earth.
So, which is it? Does conduction and convection add energy to the atmosphere? Energy that is then available to be emitted as IR radiation? Or is it solely the input of IR radiation that can provide a source of energy for the emission of IR radiation?
The inconsistency of your arguments is astounding.
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Bob Loblaw at 23:28 PM on 26 November 2024CO2 effect is saturated
CallItAsItIs @ 749:
Yes, we need to get some basics straight. You say:
In this problem, we are trying to assess warming of the atmosphere due to IR radiation eminating from the surface of the earth. This earth-emitting IR is estimated as a blackbody at about 288 deg. K, although we do consider it to be adjustable.
For energy conservation, we must take this to be the only source of energy causing addtional warming to the entire atmosphere.
...and at this point, you have the basics horribly, horribly wrong. Energy conservation applies to all forms of energy. There is no "energy conservation" that applies solely to IR radiation. Energy is conserved in a system that obtains all energy as solar radiation, and emits the same amount of energy solely as IR radiation. When you isolate one form or another, there is absolutely no requirement that solar energy be conserved, or IR energy be conserved.
From this basic misunderstanding on your part, you have created a cartoon physics that bears no resemblance to reality.
You then continue with:
The term thermal radiation is used to denote the distribution of EMR when thermal equilbrium is reached.
This, frankly, is "not even wrong". Try reading Wikipedia's page on thermal radiation. The opening paragraph starts with:
Thermal radiation is electromagnetic radiation emitted by the thermal motion of particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation.
Since you can't even get the basics right, the rest of your argument is completely illogical.
As for Eclectic's reference to the Trenberth energy diagram, here it is. Note that the only "conservation of energy" rules that applies is to the entire diagram as a whole - not the individual components (IR, solar, etc.)
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Eclectic at 19:54 PM on 26 November 2024CO2 effect is saturated
CallItAsItIs @751 & prior :-
Yes indeed, it is "ultimately the sun that drives warming of the entire earth, both the solid part and the atmosphere".
And for practical purposes, we can ignore the (fission) heat generated subterraneously, and heat generated by tidal motion, and heat generated by combustion of fossil fuels etcetera.
But when discussing atmospheric physics, it would be substantially wrong to ignore the direct heating of the atmosphere by sunlight (as short-wave radiation, including UV radiation). There is a famous "cartoon" by Dr Trenberth, giving a summary of the various energy flows in the terrestrial atmosphere ~ quite colorful, though the exact figures utilized are perhaps only accurate to about +/- 1%.
Forgive me, but I feel you are pulling my leg, when you say (with your atmospheric interest) that you have not heard of Trenberth. Just like I would feel when a Rocket Scientist says he has not heard of Newton.
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CallItAsItIs at 19:24 PM on 26 November 2024CO2 effect is saturated
Eclectic @750
Well, it is ultimately the sun that drives warming of the entire earth, both the solid part and the atmosphere. The primary mechanism for the sun warming the earth is the absorption of visible light (from the sun) into the solid portion of the earth which then acts as a near blackbody. This blackbody radiator then warms the atmosphere by conduction and convection.
It should be noted that convection is important for the CO2 greenhouse effect to work since the 15 micron absorption band of CO2 is strong enough to pack the thermal radiation from the entire band into a layer at the surface just a few tens of meters thick. Without convection, this would give us a very hot surface. Also, however, there would be a steep temperature gradient near the surface which would result in a strong pressure gradient. This pressure gradient would then drive updrafts that would carry excess heat away from the surface. In this manner, convection stops excessive heating of the bottom layer of the atmosphere.
Finally, I am not familiar with Trenberth's summary. Could you give me a link or a reference?
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Eclectic at 18:08 PM on 26 November 2024CO2 effect is saturated
CallItAsItIs @749 :-
Please do not forget about the Sun warming the atmosphere.
Also, convection and H2O phase changes, etc.
I'm fairly sure you were going to mention all these other factors, and also bring Trenberth's summary into the discussion. After all, we would be remiss if we ignored the Big Picture and focused entirely on only IR photons and the abstract "Laws of Physics".
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CallItAsItIs at 16:16 PM on 26 November 2024CO2 effect is saturated
Bob Loblaw @ 744
From this comment and several others of yours, I believe we need to get some basics straight so that you and I are consistent in our use of various term (eg. thermal radiation). Also, we need to be certain we are even working the same problem. Although I am addressing this message specifically to you, Charlie_Brown, Eclectic, and scaddenp are certainly welcome to tune in.
In this problem, we are trying to assess warming of the atmosphere due to IR radiation eminating from the surface of the earth. This earth-emitting IR is estimated as a blackbody at about 288 deg. K, although we do consider it to be adjustable.
For energy conservation, we must take this to be the only source of energy causing addtional warming to the entire atmosphere. This does not mean, however, that energy can't change forms within the atmosphere. Indeed, this is what happens in establishing thermal equilibrium. But there cannot be any change in total energy in the process. The atmosphere does not consume fuel and has no means of generating new energy.
Next, we assume that the molecules and photons are of sufficient number that it makes sense to talk about smoothly varying densities, fluid velocities, temperatures, and pressures. Also, we assume that thermal equilibrium is maintained at least locally. This is what enables us to discuss different temperatures at different altitudes.
The term thermal radiation is used to denote the distribution of EMR when thermal equilbrium is reached. If the atmosphere was totally absorptive at all EMR frequencies, then the thermal radiation would simply be given by the Planck distribution. Of course this is not the case for the entire EMR spectrum, but at wavelengths near 15 microns or other bands that are strongly absorptive, the atmospheric radiance at those wavelengths comes close to matching those of a blackbody at the temperature where the measurement is taken.
Applying this concept of thermal radiation to the TOA (about 70km altitude), we find that CO2 in effect forms a narrow bandwidth "blackbody" at the 15 micron wavelength. At this point, the detectors pick up on the emissions from this "blackbody" since there is no more CO2 at the TOA to attenuate them. This is why the last three curves that Bob Loblaw posted in 731 all show the same intensity (about 6 W/m^2) and the same temperature (about 220 deg. K) of the 15 micron band. Emissions from this band at lower altitudes and higher temperatures have all been absorbed.
At this point, we still need to discuss absorption coefficients and the Beer Lambert equation which govern the conversion of upwelling IR radiation from the surface to thermal energy of the atmosphere, but I think I will wait for feedback before I spend any more time at this.
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CallItAsItIs at 13:27 PM on 26 November 2024CO2 effect is saturated
Charlie_Brown @745
Could you please explain to me how my postings are not consistent with Kirchhoff's Law?
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Bob Loblaw at 03:54 AM on 26 November 2024CO2 effect is saturated
Regarding Charlie Brown's comment at 745 (and earlier) about thinking of Beer's Law from the perspective of the top of the atmosphere:
- Beer's Law is a probability relationship. It tells us the likelihood that a certain number of photons will be absorbed over a given distance (which is better described as a given number of absorbing molecules - it's the mass of absorbing molecules that matters).
- An individual photon maybe absorbed at the start of that path, in the middle, or at the end - or not at all.
- Beer's Law just says "on average, this portion will be absorbed".
- As we move away from the source, the probability that a photon will get that far decreases.
- When looking at what comes out of the top of atmosphere, Beer's Law tells us the probability that a particular photon came from a source at distance X (again, "distance" = number of molecules).
- There is a higher probability that it came from a close source than a distant source.
As we follow the 15um flux up from the surface, Beer's Law tells us that at each height, we're probably looking at more photons that were emitted at heights slightly below where we are, and fewer photons that were emitted far, far below where we are. There will always be 15um photons flowing upward, though.
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Bob Loblaw at 03:39 AM on 26 November 2024CO2 effect is saturated
I feel as if I'm on the verge of beating a dead horse - no idea if CallItAsItIs will respond to the latest comments, but....
I think it is useful to provide a graphic published in a 1967 paper by Manabe and Wetherald.
Figure 16 looks like this:
Note that increasing CO2 increases surface temperatures, but leads to cooling in the stratosphere. Why? Many factors, but one of them is that by adding CO2, the overall emissivity of the atmosphere increased - so the atmosphere can emit the same IR radiation to space at a lower temperature. Kirchoff's Law at work - both absorptivity and emissivity change in unison.
But CallItAsItIs has not yet caught up with science from 1967, so he believes that only the emission of "thermal radiation" is being picked up by satellite sensors, and there is no emission from CO2.
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Charlie_Brown at 03:13 AM on 26 November 2024CO2 effect is saturated
Bob’s points are spot on. CallItAsItIs sometimes uses Kirchhoff’s Law and sometimes forgets about it. There is one more interesting point that I would like to add about interpreting the graphs. They demonstrate conclusively that there are sufficient CO2 molecules to form an emitting layer (emittance = 1.0) at the bottom of the stratosphere. This shows the value of interpreting Beer’s Law by looking down from the top of the atmosphere.
CallItAsItIs misses the interpretation when he says “the intensity at 15 microns approaches a value corresponding to a 220 K blackbody. This, in turn, corresponds to an altitude of about 70 km, above which there isn't much of an atmosphere.” 220 K also corresponds to an altitude of 24 km and that is the source of radiant energy loss to space in the 14-16 micron band. How do I know? Look at the 15-micron peak, which is composed of a few very strong emittance lines, in the spectrum at 50 km. The temperature at that altitude is 270 K, but the top of the peak corresponds to the Planck distribution of 241 K. By Beer's Law, there are not enough CO2 molecules to bring the emittance to 1.0 for the strongest peak.
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Bob Loblaw at 03:02 AM on 26 November 2024Fact brief - Does manmade CO2 have any detectable fingerprint?
Rkcannon:
The paper in question, by Skrable et al, was discussed shortly after it appeared, over at AndThenTheresPhysics.
Note that the ATTP blog mentions a total of five rebuttal comments that were submitted to the journal.
Executive summary: the paper is a piece of junk.
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Eclectic at 02:33 AM on 26 November 2024Fact brief - Does manmade CO2 have any detectable fingerprint?
Rkcannon @1 :-
you mention a 2022 paper published in "Health Physics" by authors Skrable, Chabot, et al.
I gather that the journal "Health Physics" is primarily concerned with the topic of radioactivity effects on human health.
Presumably the Skrable paper had been rejected by reputable journals that normally published general scientific matters (including the physics of climate science).
Judging by Skrable's Abstract, the authors have made a colossal fundamental error in their understanding of the carbon cycle (involving the movement of CO2 into and out of Earth's atmosphere). And hence their conclusion is grossly erroneous.
The puzzle is : how did the journal Editor fail to see this error.
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rkcannon at 01:29 AM on 26 November 2024Fact brief - Does manmade CO2 have any detectable fingerprint?
Please comment on the following paper "World Atmospheric CO2, Its 14C Specific Activity, Non-fossil Component, Anthropogenic Fossil Component, and Emissions (1750–2018)" concluding "We determined that in 2018, atmospheric anthropogenic fossil CO2 represented 23% of the total emissions since 1750 with the remaining 77% in the exchange reservoirs. Our results show that the percentage of the total CO2 due to the use of fossil fuels from 1750 to 2018 increased from 0% in 1750 to 12% in 2018, much too low to be the cause of global warming." Fact or fiction?
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Bob Loblaw at 00:55 AM on 26 November 2024CO2 effect is saturated
To try to make a few points, independent of CallItAsItIs's confusion:
- All objects with a temperature >0 Kelvin emit radiation. (Planck's Law)
- As temperature increases, this shifts to shorter wavelengths (higher frequency).
- When an object primarily emits in the IR range, this is often called "thermal radiation", but radiation consists of photons, regardless of wavelength.
- At a specific wavelength (e.g. 15um), all photons are the same. They have no memory of what emitted them, and no memory of what temperature that object was at.
- There are no "thermal radiation" 15um photons that act differently.
- There are no "288K" 15um photons that act differently.
- There are no "surface-emitted" 15um photons that act differently.
- There are no "CO2 can't absorb this" 15um photons that act differently.
- There are no "CO2 will absorb this" 15um photons that act differently.
- They are just "15um photons".
- Gases are highly selective with respect to what wavelength of photons they will emit. This has to do with energy levels in the gas molecule: the structure only allows for certain energy levels, and as the molecule drops from one level to another, a photon is emitted with that energy - and photon energy is directly related to its wavelength.
- Gases will absorb photons at the same wavelengths they emit. (Kirchoff'sLaw)
- This does not mean that energy obtained from absorbing a 15um photon has to be emitted as a 15um photon.
- Energy lost by emitting a photon has to match the energy in that photon, but the energy can come from anywhere. Absorption of radiation at other wavelengths, obtaining energy via collision with other molecules (the dominant factor in the atmosphere), chemical reactions, etc.
To call it as it is, it appears that CallItAsItIs fails to understand many of these essential aspects of physics and radiation transfer.
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Bob Loblaw at 00:25 AM on 26 November 2024CO2 effect is saturated
CallItAsItIs @ 740:
Are you actually paying attention to what you are saying?
- You have been claiming that there is no 15um IR radiation above your "extinction height" (10m) for CO2 to absorb.
- I showed graphs (albeit modelled) with non-zero 15um radiation at altitudes from 10km to 70 km.
- Now, you claim that the presence of that 15um IR radiation from 10km through 70km "tend[s] to show that I [you] am right", because "the detectors are only picking up some thermal radiation from the TOA".
The level of physics denial is astounding. For your explanation to be correct, the entire atmosphere between the lower near-surface layers and the top of atmosphere layers cannot emit IR radiation in the 15um band. In your version of "physics":
- There is lots of 15um IR radiation emitted upwards at the surface...
- ...but a short distance above the surface, suddenly there is no upward emission of 15um radiation...
- ...and there continues to be no upward emission of 15um radiation as we move higher and higher in the atmosphere....
- ...until suddenly, at the top of the atmosphere, we suddenly find conditions that allow for the emission of 15um radiation so that the satellite sensors can pick it up.
- ...and somehow "thermal radiation" is some different entity that does not exist in all those layers between the surface and the TOA. It only appears at the TOA, where you need it to "explain" what is measured from space.
You are creating a physics-free zone between the surface and the TOA. In spite of the fact that the entire atmosphere has a temperature above 0K, and therefore contains thermal energy, and therefore emits thermal radiation (including 15um radiation, because the CO2 that is present can do that...), you have declared that none of that physics applies and none of the upwelling 15um radiation that is measured between the surface and the TOA exists.
...and then in comment 741, you wander off into a tangent claiming that my explanation in comment 732 requires that the atmosphere "heats itself" and "violate[s] energy conservation". That is more physics denial. Any object with a temperature >0K contains thermal energy. And the laws of physics state that any object >0K will emit radiation.
When a molecule emits radiation, it loses energy (conservation of energy maintained) and will cool, but each molecule is capable of regaining energy by collisions with other molecules, or by absorbing radiation (in any wavelength - the absorption and emission do not need to be in the same wavelength).
Remember in comment 722 when you said?:
In the case of CO2 and the 15 micron absorption band, the N2 and O2 molecules in the surrounding air collide with energized CO2 molecules which causes the extra energy (from absorbed photons) to be converted into thermal energy, thereby raising the air temperature.
The opposite is also true. CO2 can gain energy from N2 and O2 through collisions, when the N2 and O2 molecules are at higher thermal energy levels than the CO2. That is what predominantly drives the "thermal radiation" emitted by CO2 at all levels in the atmosphere. You can read the technical details in this post at Eli Rabett's blog.
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Eclectic at 17:36 PM on 25 November 2024CO2 effect is saturated
Charlie_Brown @739 :-
Our two-way conversation is getting rather off-topic for this thread.
I am sure that we two are "on the same side" regarding AGW/science. But there is clearly a large semantic discrepancy with our individual understandings of the meaning of certain English words ~ and it would take far too long for us to negotiate a mutual agreement on the semantics.
Let it slide.
The point which I found interesting (and which I always find interesting in reading all the nonsenses, bad science, and Motivated Reasonings to be found on the WUWT website) . . . is that our new friend [viewed @722 ; @723 ; @726 ; @730 ; @740 ; and @741 ] and suchlike people ~ are coming to pseudo-science conclusions because of poor logic and poor understanding of the physical universe of particles & photons. They are hampered by their confusions of realities vs abstractions (e.g. the mental constructions achieved by the great scientists of the 18th, 19th, and later centuries. Constructions which have been dignified by the label "Laws" ) .
[ Off-hand, I do not know of a suitable thread on SkS , for the discussion of the philosophy of science as expressed through human psychology & semantics. ]
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CallItAsItIs at 15:11 PM on 25 November 2024CO2 effect is saturated
Bob Loblaw @732
Regarding your comment
Please buy a clue, CallItAsItIs. We do not need to "bring an IR source up there" - there already is one. It's called "the upper atmosphere", it contains CO2, and it is warmer than 0K. Climate scientists actually know about this obscure "upper atmosphere" as a source of IR radiation, they know how to calculate its effect, and they know it plays a role in atmospheric greenhouse warming.
Are you saying that the atmosphere heats itself!? Wrong! This would violate energy conservation. In order to to heat the atmosphere, we must bring in IR from outside the atmosphere. In the case of greenhouse warming, this is the 288 K IR eminating from the surface of the earth.
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CallItAsItIs at 14:44 PM on 25 November 2024CO2 effect is saturated
Bob Loblaw @ 731
I hate to disappoint you, but your curves tend to show that I am right. As the observation altitude increases, the intensity at 15 microns approaches a value corresponding to a 220 K blackbody. This, in turn, corresponds to an altitude of about 70 km, above which there isn't much of an atmosphere. Therefore, for the 15 micron band, the detectors are only picking up some thermal radiation from the TOA. Any upwelling radiation from this band has already been completely absorbed at lower altitudes.
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Charlie_Brown at 13:54 PM on 25 November 2024CO2 effect is saturated
Eclectic @737,
I strongly disagree with your description of the laws of science. The definition is not like legalistic law. Understanding and applying them properly is in no way lazy. They are not concepts. In the scientific use of the word, they are physical reality. The laws of gravity, conservation of energy, the 2nd law of thermodynamics, and radiant energy transfer have never been found to have been violated. But it does take knowldege and careful thought to apply them correctly. It is like the old cliché about statistics never lie but liars use statistics. Statistics are rigorous but too many people use them improperly.
Yes, I know the thread about the 2nd law of thermo about a colder thing cannot warm a warmer thing. I answered the issue with Gerlich & Tscheusner’s paper @1535 by pointing out that G&T made a mistaken assumption that the mechanism of global warming was “radiatively equilibrated.” Since global warming results from an upset to steady state equilibrium, there is no violation of the 2nd law. Understanding the law and G&T mistaken assumption should have put a stop to that myth.
In this case, Beer’s Law (I use that term now as Beer focused on concentration while Lambert focused on column length, but both convey the same concept, the atmosphere essentially has a fixed column length) is only one part of the mechanism of global warming. As I tried to say very clearly to CallItAsItIs, he errored by not applying Kirchhoff’s Law. Anyone who doesn’t understand it should study it before making comments before spreading misinformation. Errors made by science denialists need to be found and explained. I think that using the laws of science is the best way to be convincing. The challenge is to find the errors and explain them in understandable terms.
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Bob Loblaw at 12:08 PM on 25 November 2024CO2 effect is saturated
Electic:
The issue with Beer's Law is not that it is incorrect - it's that it is incomplete. It only deals with the absorption side of the radiative transfer process. It says nothing at all about the emission side. To properly describe and understand the greenhouse effect and IR radiative fluxes (upwards and downwards), you need both. Beer's Law only gets you half way there.
It's kind of like trying to balance your bank book by adding up all the deposits and ignoring the withdrawals (or vice versa).
There is useful discussion of Beer's Law on this "From the email bag" post (now almost three years old). In particular, read the first few comments where Charlie Brown and I start to discuss the "extras" needed to complete the picture.
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Eclectic at 11:27 AM on 25 November 2024CO2 effect is saturated
@735 :-
Thank you, Charlie_Brown, but please look to the main thrust of my comment.
Which is that: regardless of Beer's Law, Bouguer's Law, Lambert's Law, Kirchhoff's Law, Thermodynamics Law(s), etcetera . . . we must not get in the rather lazy habit of accepting famous "Laws" in an automatic way ~ by taking the legalistic approach that holds that words & concepts are equivalent to actual physical reality (rather than as sometimes convenient guides).
I'm sure you have seen that sort of thinking quite often with Climate Science Deniers who assert that "a colder thing cannot warm a warmer thing" (and so on).
Sometimes the old "Laws" are fine in most circumstances; sometimes they are useful as approximations ~ but "Laws" are essentially concepts rather than hard realities of particles/photons. And they can ~ sometimes ~ mislead our thinking. Beware of Laws.
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scaddenp at 10:34 AM on 25 November 2024CO2 effect is saturated
CallItAsItIs - posters above are trying to educate you about how to work with atmospheric physics but so far you appear to be very reluctant to understand the points made.
Can we agree as a starting point that nature has the final say? Ie the basis of science. You are proposing a, let's say, novel hypothesis for physics where as climate science is using the long established model of radiative transfer. That model allows us to predict what instruments on ground, balloon, satellite will measure for spectrum (and many other things as well). Your hypothesis would give very different observations.
Are you prepared to let the observations decide the argument? -
Charlie_Brown at 10:08 AM on 25 November 2024CO2 effect is saturated
Eclectic @ 734
The fundamental laws of radiant energy, including Beer’s Law, are entirely germane to the mechanism of global warming. They are not mental shortcuts. Einstein was in another league when thinking about the theory of relativity.The problem for CallitAsItIs is that he does not apply Beer’s Law correctly as it applies to radiant energy leaving the top of the atmosphere. He views, incorrectly, attenuation of the original source radiation from the surface, calling it “extinction.” This is the same mistake that Angström made in 1900 and too many others have followed since because it overlooks Kirchhoff’s Law. Bob Loblaw gets it right because he uses the MILIA (MODTRAN Infrared Light in the Atmosphere) model looking down from the top of the atmosphere at 70 km. Beer’s Law is very important because it defines the molecular density in the atmosphere that raises the emittance of a specific wavelength to a value of 1.0. Note that the minimum atmospheric temperature for the Tropical Atmosphere is 195 Kelvin at 17 km. The reason the bottom of the CO2 trough begins to rise at higher altitudes is the increasing temperature of the ozone layer. This demonstrates clearly that there are sufficient CO2 molecules, by Beer’s Law, to form an emitting layer at that altitude.
It is enlightening to run the model at 10 meters looking down. The spectra follows the Planck distribution because all source photons from the surface that are absorbed by CO2 are re-emitted. Kirchhoff's Law.
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Eclectic at 07:33 AM on 25 November 2024CO2 effect is saturated
CallItAsItIs :-
Your explanation falls short of reality.
At the planetary scale, the "Beer-Lambert Law" is not germane to the situation (see Bob Loblaw's further comments, above).
Always beware of "Laws" composed centuries ago. The so-called Laws were useful as mental short-cuts, in some but not all circumstances.
As Einstein would say: Take your nose out of the lawyers' books, and look at the real universe.
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Bob Loblaw at 07:14 AM on 25 November 2024CO2 effect is saturated
I noticed that CallItAsItIs, in comment 730, has stated that his "extinction height" is a mere 10m. If this actually prevented there from being any upwelling 15um radiation above that height, then all the graphs I supplied in comment 731 should show zero for intensity at 15um.
The astute observer will note that the graphs do no such thing.
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Bob Loblaw at 07:02 AM on 25 November 2024CO2 effect is saturated
CallItAsItIs @ 730 once again completely ignores the known and measured fact that upwelling IR radiation at 15um, as measured at high altitudes, does not need to come from the surface.
He even has the answer in his comment (emphasis added):
Regarding the CO2 molecule at 50000m, it most certainly can absorb the 15 micron IR photons — if you bring an IR source up there.
Please buy a clue, CallItAsItIs. We do not need to "bring an IR source up there" - there already is one. It's called "the upper atmosphere", it contains CO2, and it is warmer than 0K. Climate scientists actually know about this obscure "upper atmosphere" as a source of IR radiation, they know how to calculate its effect, and they know it plays a role in atmospheric greenhouse warming.
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Bob Loblaw at 06:54 AM on 25 November 2024CO2 effect is saturated
To show how CallItAsItIs is wrong, let's look at the upward-directed IR radiation calculated using the MODTRAN model I mentioned in comment 725. We'll stick to the default tropical atmosphere with no clouds - changing only the altitude we're looking down from.
Let's start at 10km altitude.
Lots of radiation at 15um there. Haven't reached "extinction" yet. Lets' go higher, to 20km...
A substantial reduction in 15um intensity. Are we close to CallItAsItIs's "extinction" height yet? Let's go higher, to 30km...
Oh, no! IR intensity at 15um has increased! How on earth is that possible? Where are those 15um photons coming from? If they were blocked from reaching 20km (from the surface), then how can they possibly be appearing at 30km altitude? At 30km, we're now in the stratosphere and the atmosphere is getting warmer again. Could it be possible that this warmer atmosphere is actually emitting 15um photons?
Maybe we need to go higher. Try 50 km.
Oh, crap. 15um intensity is even higher. Let's try 70km.
That's almost the same as at 50km.
So, where is this "extinction" point where CallItAsItIs claims there will be no more 15um IR radiation for CO2 to absorb? That "extinction" point only exists in CallItAsItIs's imagination.
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CallItAsItIs at 06:54 AM on 25 November 2024CO2 effect is saturated
Eclectic @728
The extinction altitude of an absorption band of a GHG is the altitude at which the upwelling radiation with the band becomes negligible according to the Beer-Lambert law and the absorption coefficient of the band. For CO2, the absorption band is 14-16 microns and the extinction altitude is about 10 meters. This means the upwelling IR radiation absorbed by CO2 at the top of the credible atmosphere is pretty miniscule. Above that, of course, it is zero.
Regarding the CO2 molecule at 50000m, it most certainly can absorb the 15 micron IR photons — if you bring an IR source up there. The reason there is no absorption at that altitude is because all 15 micron IR has already been absorbed at lower altitudes.
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Charlie_Brown at 06:44 AM on 25 November 2024CO2 effect is saturated
First, thanks to Bob for the call out. Studying the post and the linked article in Chemical Engineering Progess should be an effective means of education.
CallitAsitis @726:
You have a misunderstanding of Kirchhoff’s Law: Absorptance = Emittance (at thermal equilibrium, i.e., temperature not changing) A CO2 molecule absorbs a photon related to a specific wavelength, increasing its internal energy level. It collides with adjacent N2 and O2 molecules and transfers energy so that the molecules are in thermal equilibrium. Since CO2 still vibrates, it also emits photons at specific wavelengths. For the molecule, the net result is essentially a pass-through. For a column of atmosphere, it is not conservation of photons but conservation of energy.You also have a misunderstanding of the absorptance/emittance lines for CO2 and water vapor. See Figure 3 in the post linked by Bob. The Stefan-Boltzmann Law is applied to each line:
Intensity = emittance x Stefan-Boltzmann constant x absolute temperature to the 4th power.Your understanding of absorptance/emittance as a function of altitude is not correct. Energy loss to space is best conceptualized by looking down from the top of the atmosphere, not by looking up from the surface. Looking down, Beer’s Law determines the altitude at which there are sufficient molecules in the optical path to bring the emittance to 1.0. For strong CO2 emittance lines, it is the cold, thin atmosphere at the bottom of the stratosphere. For weak emittance lines, it is at a lower, thicker, warmer altitude, with a minimum altitude being the Earth’s surface which emits as a blackbody. As CO2 increases, the molecular density in the cold upper atmosphere increases, the weak emittance lines strengthen, and intensity of emitted energy decreases because of the lower temperature.
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Eclectic at 06:20 AM on 25 November 2024CO2 effect is saturated
CallItAsItIs @726 (and prior) :-
You are expressing yourself in an unclear manner ~ almost bizarrely.
e.g. What is the term "extinction altitude" that you use?
And why do you say that a CO2 molecule "can no longer absorb" (at the 15 micron wavelength) when the molecule is at say 50,000m altitude versus when the molecule is at say 50m or 500m altitude? Please explain.
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Bob Loblaw at 06:11 AM on 25 November 2024CO2 effect is saturated
CallItAsItIs @ 726:
Frankly. you don't know what you are talking about.
- If IR radiation is present in a band that CO2 absorbs at, CO2 can absorb it.
- If CO2 is present at a temperature above 0K, it will emit IR, and do it in exactly the same bands that it absorbs at.
- Since the entire atmosphere, at any altitude, contains both CO2 and is at temperatures above 0K, there will be CO2 that is both absorbing and emitting IR radiation in the 15um band.
I know this seems like a difficult concept for you to grasp, but the atmosphere has more than just a top and a bottom. In fact, almost all of the "credible atmosphere" exists in the zone between the top and the bottom, and until you learn that you will continue to spout garbage.
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CallItAsItIs at 04:56 AM on 25 November 2024CO2 effect is saturated
Bob Loblaw@724
Above the extinction altitude of the 15 micron band, CO2 can still emit IR radiation (at any wavelength) but can no longer absorb within this band. The fact that CO2 can no longer absorb within this band means that it has zero greenhouse forcing at this altitude and above for the simple reason that there is no more 15 micron radiation that can be absorbed. The small amount of 15 micron energy that reaches orbital sensors comes from blackbody emissions from the top of the credible atmosphere. This radiation cannot, however, be absorbed since there is no more atmosphere.
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Bob Loblaw at 03:06 AM on 25 November 2024CO2 effect is saturated
As an FYI, the IR flux vs altitude question (both upwelling and downwelling) can be explored using the online MODTRAN model. To start, I suggest reading this blog post guest-authored by frequent reader/commenter Charlie Brown.
