Sure, the Greenhouse effect of CO2 is real, but to assume that the effect continues indefinitely is unwarranted. If your corn gowns to 6 ft in 3 months, it doesn't mean it will grow to 12 ft in 6 months. The 14-16 micron band is already totally absorbed at well below the present 400ppm.
Since the band width is determined by the 15mm spike and the Doppler effect, doubling CO2 makes no difference.
Why do activists shy away from experiments to prove their Hypothesis? Perhaps they are not confident of the outcome.
Refer: NASA Technical Memorandum 103957 Appendices E and F. Lord, 1992
"the Greenhouse effect of CO2 is real, but to assume that the effect continues indefinitely is unwarranted."
With increasing CO2 the temp does continue indefinitely as long as CO2 concentration in the atmosphere continues to go up, but the CO2 concentration/temp curve is logarithmic so its not a one to one increase.
What do you make of the experiment I provided above. It shows clearly that CO2 has an impact from at least 13um through to 18um, and that the effect is not saturated near the edges of the band.
I think the effect seen there is "smearing", due to the coarseness of the instrumentation used in NASA Nimbus 4. (That seems to be the source of the "actual", I don't know the source of the "theoretical") Compare the "Theoretical" curve with the NASA Lord data, which shows the total extinction in the 14-16 micron band and very sharp edges. A condensed version of this data had been shown on the web site of the Gemini IR Astronomy project, but since taken down. It still can be found on an unattended page there. A copy can be found on page 18 of my little booklet "Carbon Dioxide-Not guilty". Also a plot showing a 1% increase in absorption by doubling from 400-800ppm. The booklet is available on kindle for 99c, or as a free PDF to anyone sending me their email. bobhisey at comcast.net.
The key word is significant. The Doppler effect is taken to be a bell curve, so in theory extends to infinity. But not in practice, where one assumes a cut off at, say 3 sigma. Or there is little difference between 99% extinction and 100%. Our instrumentation foes not catch the last few elusive photons.
Accuracy is more important than precision in determining actions.
The only way to satisfactorily conclude this discussion is a test of actual absorption at 400 and 800 in the same lab with the same equipment and conditions.
There are measurements in the literature from 1920-1970, but none are the above. They seem to concentrate on the two shorter wavelength bands.
I think you might enjoy my little booklet, I hope you get it.
I don't think "smearing" is an instrumentation issue: pressure broadening is a real physical phenomenon (or: set of phenomena).
Absorption/emission spectra broaden at higher atmospheric pressures. Which means the absorption/emission spectra of CO2 at sea level are different from at 10k feet, 20k feet, 50k, etc.
We get some interesting results from this. For instance, at higher altitudes, there's less overlap between H2O's and CO2's bands.
Smearing is my worrd for the effect of the precision of the instruments. Take CO2 at 15 microns, band width 2 microns. If the instruments precision is say 5 microns, it will never show zero, as it will still be influenced by the lower absorptions outside the 14-16micron band.
The measurement would start being influenced by that band at 21 microns and extending to 8 microns. I.E. the 2 micron sharp band would be "smeared out" to some 13 microns.
I have no knowledge of the presicion of the instrumentation in the actual satellite. But since it does not show total absorption at 15 microns, it must be less precise than 2 microns. That makes sense as it would be difficult, and very expensive., to have really precise Laboratory in a satellite. One could get an estimate back calculating from the shown curve. See the detailed NASA data at Nasa Technical Memorandum 103957. Or a handier form in my little booklet "Carbon Dioxide - Not Guilty", 99c at Kindle amazon, or free to anyone who sends me an email address.
Band width is determined by the Doppler effect. A bell shaped curve, with the tails cut off beyond 2 to 3 sigma.
Various methods of calculating how fast the 14-16 band is absorbed, agree that it will be totally (99.9%) within 2 to 3 thousand feet. So pressure effect is minimal.
My biggest problem is the lack of laboratory data to prove/disprove the assumtption that doubling CO2 from400 ppm to 800ppm woudl cause a very substantial increase of heat absorbed by the CO2. There is nothing in the literature even close to such an experiment.
Here we are, spending trillions on an unproven assumption!
In science I was taught first form an hypothesis, then prove it, then act on it.
If the spectrometer used had low resolution, how come there are narrow spikes in the center of the ozone and CO2 bands? Answer: the spectrometer used in this experiment is, in fact, high resolution, probably Fourier Transform. The resolution is at least as good as the half-width of the narrowest peak.
In the center of the CO2 band, the absorption near the surface is greater than 99% at path lengths of a meter or so, much, much less than 2 to 3 thousand feet. But the graph depicted is emission, not absorption. The reason you see a valley is that the effective emission altitude increases with increasing absorption and it's colder at higher altitude and the CO2 emits at a lower rate. There is an exception, though. Some of the emission in the center of the valley is generated in the stratosphere where temperature increases with altitude and absorption is minimal. That's why you see a sharp peak at 667 reciprocal centimeters. If the measurement were taken at the tropopause, the bottom of the emission valley would be flat.
The absorption is saturated yes but if the Co2 concentration increases, the altitude from where the radiation leaves the atmosphere increases. With increased altitude comes a lower temperature (if not in the stratosphere). Lower temperature decreases the amount of energy radiated from the stmosphere. The earth warms.
I can not follow your comment. It seems you are saying that radiation leaving the atmosphere originates in the atmosphere, not from the earth. There is no measureable radiation originating in the atmosphere.
Simple physics wins. Established fact, If co2 incresase, the total absorption of the 14-16 micron band occurs at a lower level. In either case, there is no radiation in this band remaining to leave the atmosphere. so no net change in global warming.
Do you know Planck's law of emission? Do you believe it? Emissivity and temperature are the factors that affect emission of radiation at each wavelength.
Have you read any textbooks on radiation?
I don't expect coherent answers but other readers who are undecided might get the point.
I am fully aware of plancks law, which is based on black bodies. As a PhD scientist, of course.
Are you? Please refer to "Radiative Heat Transfer" by MichaelF.Modest. The bible
Air or CO2 are not black bodies, far from it. They can be cosidered white bodies. A CO2 molecule energized by a IR photon of the correct wavelength takes about 1second to re-emit it. In that time it has had a billion collisions with O or N atoms where the energy is released in the form of velocity or heat. So it can be thought of as being 1 tenmillionth blackness and the rest white.
We are not supposed to use agruments ad hominem in this discussion.
What do you make of the NASA data showing zero transmission from the atmosphere in this 14-16 micron range. That is, no transmission from the earth or from energized CO2.
This data has been happily in use for 30 years by the IR Astronomers evidencing its reliability. (NASA Technical Memorandum 103957, App. E). Additional evidence is that a green activist high in NASA took the risk and trouble of burying this data where it could not be found by search engines Please share with us your factual basis for not using/trusting this data?
As far as your refence, it appears to show no radiation increment for CO2 in the 14-16micron band. Check the lower graph in Fig 11.
I trust this is coherent enough for you. If not please inform me.
I think his point is that there is no measureable radiation from Earth as a whole that originated in the atmosphere. The radiation that does originate in the atmosphere ultimately gets reflected back to the ground, rather than pass through the atmosphere. The plots in NASA Technical Memorandum 103957, App. E (https://ntrs.nasa.gov/citations/19930010877 -- see plots #16-18 on p. 113-115) support the proposition that no energy from the 14-16 um band is transmitted through the atmosphere. (I'm not arguing for or against his point, just trying to explain it as I understand it.)
"My statements apply only to the 14-16 micron band. Photons in this band have been shown to never reach space. That is, the absorbance by CO2 and transference to heat in the atmosphere vastly outweighs the occasional re-emittance of a photon of that wavelength."
Frank: Photons in this band are emitted to space by our planet all the time. Experimentally we observed them from space continuously. However the photons that are reaching space are not the ones that are emitted by the surface. They are emitted from 10 km above the surface or 20 km above the surface. At 15 km above the surface, we are above 90% of the atmosphere and the mean free path between emission increases 10-fold for photons absorbed by CO2 and far more for photons absorbed by water vapor since the atmosphere gets much drier with altitude.
Your use of the phrase "re-emittance" suggests a possible misunderstanding. Absorbing a photon of thermal IR radiation produces an excited vibrational, rotational or a combinations of vibrational+ rotational excited states. (That is why the 15 um line for CO2 can be resolved into dozens of nearby lines under some conditions). The excited vibrational state has a half-life of about 1 second and collisions occur about 10^9 times a second near the surface, though not every collision is capable of relaxing an excited state. Therefore re-emission of an absorbed photon from the excited state that produced it is not a significant process in the troposphere and lower stratosphere where all the important absorption and emission appear. The energy from the excited state end up increasing the velocity of the colliding gas molecules, increasing their temperature. This process is sometimes called "thermalization".
Essentially all of the excited states that emit photons are created by "collisional excitation". Collisional excitation produces a Boltzmann distribution of energy among all possible excited states (with exp(-E/kT) fewer molecules with in an energy state E above ground state. When deriving Planck Law (and the Schwarzschild equation) we assume a Boltzmann distribution of energy states. Therefore Planck's Law has mathematics that ensures that it needs to be at least 1000 degK to emit a significant number of visible photons, but the atmosphere and surface emit "thermal IR photons" at 190-310 degK. When a Boltzmann distribution of excited states exists (and energy is being exchanged by collisions much faster than by photons of any other process), we say the atmosphere is in "local thermodynamic equilibrium". (This does not mean emission and absorption are in equilibrium). Normally we need to heat something to several thousand degK to get it to emit a significant amount of visible light, but we have invented some devised that allow us to create a lot of excited states without collisional excitation, where a Boltzmann distribution of energy states does not exist and visible light can be emitted without high temperature. LED, lasers, fluorescent light bulbs and microwave ovens are devices that create a non-Boltzmann distribution with far more excited states than normal.
Hey Frank, back on "Natural Variability, Attribution and Climate Models #5", you said:
"There is a fundamental problem with emission of radiation when it is presented as emission of blackbody radiation in basic undergraduate courses" - and you go on to talk about emissivity.
But I'm looking at "Principles of Planetary Climate", which is a very popular textbook for introductory climate science classes, and emissivity vs blackbody is addressed in chapter *3* That is: pretty early in the overall arc of study for any serious student of climate science. The book goes on to immediately discuss Kirchoff's Law of Radiation.
It's completely, 100% fine to point out that atmospheres don't actually absorb/emit blackbody radiation (which would include unit emissivity/absorbtivity). But does this really make for a serious critique of how climate science is taught in college programs, when introductory texts also address this point rather early?
Here's where I'm coming from: in many of the internet discussions I've seen on this subject, I see skeptics and deniers say "well, what about X?!? Have scientists addressed *that*?" and you find that "X" is some point of science that scientists talked out a century ago - the effect of water vapor is a good example. Or, just more generally, it often seems like many "skeptics" never picked up textbooks on the subject to actually study deeply and learn what the scientists are saying. They're operating based on what they *heard* from other skeptics that scientists are saying - and there's a disconnect between what the skeptics understand the science to be, versus the *actual* state of the science as taught in universities and accepted by leaders in the field.
And then I have kinda gotten frustrated by that disconnect; it seems like laziness on the part of the skeptics: if you're going to criticize a field, get educated about it first.
So this conversation has drawn *lightly* on that frustration, 'cause it *feels* like you're doing a little bit of the same. When you say that CO2 particles' extra radiation-emission makes up for their extra radiation-absorption, it seems like you're missing some understanding of the basic mechanics of radiative optics. I might be misunderstanding your position - but, regardless, this is where I'm currently coming from.
Physicists have lousy explanations for emissivity and most climate scientist as busy at explaining physics. What is emissivity? Well, the emissivity of many metals can be changed by polishing the surface or a thin coating of oxide on the surface. Emissivity therefore must be a phenomena that develops at surfaces or interfaces. Emissivity equals absorptivity (reflectivity) which is a phenomena that occurs when incoming radiation encounters a surface - another surface phenomena. In the case of water, it is easy to think in terms of incoming radiation being partially reflected outward by the surface and radiation traveling through water being partially reflected inward at the surface. That would explain why water has an emissivity less than 1 (and which depends modestly on wind disturbing the surface.) Gases have no surface, so my hypothesis is that they have an emissivity of 1. Does blackbody radiation travel through solids and get partially reflected as it exits the surface resulting in an emissivity less that 1? That's my explanation. And the same fraction of radiation coming in from the air is reflected at the same surface. Beware: I can't find this explanation anywhere, it is self-"taught". People talk about energy traveling through solids in terms of phonons (quasiparticles of sound or vibration in a solid lattice) not photons or electromagnetic waves. This is a subject I haven't even explored. What does solid-state physics tell us about what happens when a phonon encounters a surface? Does it get reflected or result in the emission of a photon? Liquids like water don't have a lattice and no one has a problem imagining photons traveling through them - unless we talk about mercury metal.
"What is emissivity? Well, the emissivity of many metals can be changed by polishing the surface or a thin coating of oxide on the surface. Emissivity therefore must be a phenomena that develops at surfaces or interfaces."
*Whoa*, there!
Just because surfaces are often optically active doesn't mean that *only* surfaces are optically active. The interior of materials can be optically active, too! Optical phonon modes inside a crystalline material can catch/emit light, individual molecules can absorb light corresponding to an electron gap (this is how many dyes work), or crystalline defects can alter the local ev gap. And there are many, many other ways for atoms to couple for oscillating electrostatic fields -- which makes them optically active.
Surfaces are *absolutely* not required for photons to be absorbed or emitted. This is flat wrong.
Emissivity/absorptivity approaches 1 at some wavelength simply when there are enough optically-active material to absorb close to all of the incoming light at that wavelength. How much material this takes depends on the type of material (obv), and things like metals absorb and reflect easily because of the lack of band gap, because there are many free electrons that are available to absorb the incoming electromagnetic energy and there is no gap between the valence and conduction bands. Gases, by constrast, don't have the same free electrons and have specific band gaps, making them optically active only at specific frequencies (setting aside pressure broadening or similar effects). And gases are likewise much less dense, making their absorptivity / volume rather lower.
"People talk about energy traveling through solids in terms of phonons (quasiparticles of sound or vibration in a solid lattice) not photons or electromagnetic waves."
Phonons can be optically active! Meaning, light can be absorbed, turned into an optical phonon, which then is transmitted through the material, and then the phonon losslessly turns back into a photon on the other side. Or maybe the photon passed through without being absorbed at all - this also happens. (Or a mix of the two).
The emissivity/absorptivity of a gas varies with wavelength and somewhat with pressure. But I don't think it can ever be equal to 1. That would imply that every photon that came within the effective radius of the molecule would be absorbed. I don't believe that's true. The absorptivity/emissivity of a molecule can be high, but the emitting area is small. That's why you need lots of them.
DeWitt: Nice to hear from you again. Dense (non gaseous materials have an emissivity usually have an emissivity less than unity. For some metals, emissivity can be much less than unity. No matter how thick a layer of polished copper (emissivity 0.04) may be, its emission of thermal IR at 300 K can never exceed 0.04*o*300^4 according to the Stefan-Boltzmann Law.
Now let's consider CO2 molecules. As you say, their emitting are is small, and we need many of them to get much emission. So let's cram those CO2 molecules next to each other so tightly they are about as close as copper atoms in solid. That will give us lots of collisional broadening. The easies place to imagine this happening near the surface of Venus. Will the gas emit the full o*T^4, or does the gas have an innate emissivity that limits how much radiation can be emitted from a layer to something less that o*T^4 - even when we make that layer as thick as we want?
Thickening a layer of polished copper doesn't increase the number of photons because emissivity less than unity is a phenomena that develops at the surface and affects emission and absorption equally. If we roughen the surface of the copper, the emissivity and absorptivity go up. (This may involve surface oxidation). I first learned to think of emissivity as a phenomena associated with the surface of a material from comments your made years ago. Gases have no surface and therefore should emit o*T^4 when enough gas is present to set up an equilibrium between emission and absorption - which Planck used to devise his law.
Now, it may not be sensible apply the term emissivity to a gas when we probably can't do an experiment to measure it and I need a thought experiment involving very non-ideal CO2 in the atmosphere of Venus to explain my rational.
Yes, Ben. Many skeptics are lazy and don't know about subjects like radiation transfer. When they come across something they don't understand, the simple answer is that there must be a conspiracy to hide the fundamental flaw in climate science they have discovered. The idea of a conspiracy involving the fundament physics of radiation interacting with radiation is absurd.
Are there conspiracies among climate scientists not to talk about weaknesses of climate models and the possibility that climate sensitivity might be on the low end of the old 1.5-4.5 K/doubling? Probably. At least one climate scientist has admitted not being willing to talk publicly about some controversial issues and problems because "deniers" will seize on these problems and exaggerate them on FOX News. In a talk on Youtube, a modeler confessed that all climate models produce far too few marine boundary layer clouds, the clouds that reflect SWR without greatly reducing OLR, the clouds that cool the planet the most. I haven't found this in any papers. None of these problems mean that rising GHGs don't warm the planet, just that they might warm the planet modestly less than expected. Skeptics usually don't care much about the possibility of modest reductions in climate sensitivity; they prefer to blow up the whole idea. Global warming is a hoax.
Ben asked: "When you say that CO2 particles' extra radiation-emission makes up for their extra radiation-absorption, it seems like you're missing some understanding of the basic mechanics of radiative optics. I might be misunderstanding your position - but, regardless, this is where I'm currently coming from."
Fundamental understanding of radiation transfer is contained in Schwarzschild's Equation for Radiation Transfer. This equation predicts how radiation is changed as it travels through an atmosphere of absorbing/emitting molecules with a given altitude-dependent composition and temperature profile. The user needs to specify the amount of radiation entering from one direction and where it leaves. [More fundamentally the physics of radiation transfer starts with Einstein coefficients for absorption, emission, and stimulated emission of photons and energy levels in molecules, and then adds mechanisms of line broadening. However, if you start with absorption coefficients and other spectral information on GHGs that can be measure in the laboratory, you can start with Schwarzschild's Equation (assuming local thermodynamic equilibrium exists and that stimulated emission is negligible, both of which are true where most absorption and emission occurs).
Schwarzschild's Equation predicts that upwell radiation from the surface is reduced from the about 390 W/m2 of blackbody radiation emitted by the surface to 240 W/m2 by the time radiation reaches space. With doubled CO2, only about 236.5 W/m2 will reach space, a 1.5% reduction. So doubling the number of photons emitted and absorbed by doubling the number of CO2 molecules has - to a first approximation - no impact on radiative cooling to space. Instead of doubling absorption on the way to space, emission from doubled CO2 replaces 98.5% of the additional photons being absorbed.
Here is an intuitive way of looking at the problem: Consider a layer of atmosphere somewhere above the ground. The CO2 molecules emit equal number upwards and downwards, so doubling CO2 merely sends twice as many each direction, which doesn't change speed up or slow down radiative cooling to space. Now consider the upwelling and downwelling radiation entering this layer. CO2 absorbs a certain FRACTION of the radiation incoming from each direction. If the upwelling radiation from below - emitted from where it is warmer - is more intense than the downwelling radiation from above - emitted from where it is colder - THEN more photons disappear from the upwelling flux than the downwelling flux. This slows radiative cooling to space. Now, if you are talking about the wavelength that is absorbed most strongly by CO2 and where 90% of the incoming photons are absorbed within one meter and replaced with newly emitted photons, the upwelling and downwelling photons were emitted where the temperature is basically the same and the intensity of these fluxes will be identical and have blackbody intensity. However, if you move to the shoulder of the CO2 absorption band, where the average photon might travel 1 km between emission and absorption, the temperature difference will be 2*6.5 degK and (if my calculations are correct), the upward flux might be 43 W/m2 stronger than the downward flux from this temperature difference. This is why the outward flux of radiation decreases from 390 W/m2 at the surface to 240 W/m2 at the TOA, while the downward flux increases from 0 W/m2 at the TOA to 333 W/m2 at the surface. And why doubling CO2 slows radiative cooling to space only a little bit.
You can see how doubling CO2 effects upward radiation transfer through the atmosphere at different wavelengths at our host's old blog in Figure 15 and 16 and in a lower resolution Figure in Wikipedia:
“ Notice that when climate scientist say CO2 traps heat in the atmosphere (by absorption), they are grossly simplifying.”
Wrong! They are not oversimplifying at all. They are talking pure nonsense. No substance “traps heat”. To claim otherwise simply means you don’t know what heat is. Radiation is not heat. 15μm radiation has a corresponding temperature of -80 °C. The troposphere is defined by molecules with a temperature of -60 °C and above. Absorption and emission of 15μm radiation by CO2 cannot heat any molecules in the troposphere.
"The latter case is the one that is always correct, but if you stack enough optically thin layers on top of each other, they will eventually absorb enough of the radiation emitted by other layers that they will emit radiation like a blackbody"
Point: optically-thick layers will generally not emit or absorb like a blackbody.
For an optically-thick layer, the absorptivity/emissivity *at some frequencies* will be close to 1, but there will still also be frequencies where the absorptivity/emissivity is much less than 1. That's what make these not-a-blackbody.
Blackbodies absorb indiscrimately and vary in emission only according to temperature, while optically-thick atmospheres will still preferentially emit/absorb some frequencies over others.
Ben: By definition, when someone refers to an optically-thick layer of atmosphere, they are postulating a layer that emits like a blackbody. There is no such thing as an optically-thick layer on Earth. You'll find other people who say that the emissivity of an optically thin layer is less than 1. These abominations arise because climate scientists want to start the discussion with familiar blackbody radiation, which by the derivation of Planck's Law is radiation where emission and absorption are in equilibrium.
Schwarzschild's equation is mentioned on p 190 of Principles of Planetary Climate, but you will find nowhere that it says radiation transfer in a non-scattering atmosphere is calculated using this equation. The version on p 190 is meaningless to me. There are much more intuitive (for me) versions of this equation. The incremental change in the spectral intensity (dI) of radiation of a given wavelength as it travels an incremental distance (ds) through an atmosphere is caused by emission and absorption from molecules along that path:
dI = emission - absorption
dI = n*o*B(lambda,T)*ds - n*o*I*ds
where: n is the density of absorbing/emitting molecules
o is the absorption cross-section at the wavelength of interest.
B(lambda,T) is Planck's function
and I is the spectral intensity of the radiation entering the increment of distance.
The absorption term on the right should be familiar from Beer's Law. Schwarzschild's equation simplifies to Beer's Law when absorption is much greater and emission. This is the case in a spectrophotometer, which uses a powerful light source to overwhelm emission. The emission term on the left is formulated exactly the same way as the absorption term except the emission cross-section is o*B(lambda,T), which is true when local thermodynamic equilibrium exists. When dI is zero, I = B(lambda,T) and we are discussion radiation of blackbody intensity where emission is balanced by absorption.
Many discussions iof Blackbody radiation gnore the fact that Planck's law gives the spectral intensity of radiation traveling outward from a point, and simply show the formula for the flux of blackbody radiation emitted perpendicular to a plane after integration over a hemisphere (which adds a factor of pi to the formula). We can simply Schwarzschild's equation with a similar trick by considering only the vector components of radiation transfer perpendicular to the planet's surface. They are the only ones that warm and cool the planet. The horizontal components cancel. This replaces ds with dz. This is called the two-stream approximation, and allows us to think in terms the changes in a upwelling flux and downwelling flux.
Now n, o, T and I are all functions of z and should be written n(z), T(z), I(z) and o(lambda,z). And you have to numerically integrate Schwarzschild's equation over a path (say from the surface to space) and overall relevant wavelengths and in practice over all angles in a hemisphere.
PierreHumbert and everyone else always always "simplifies" to:
dI = [B(lambda,T) - I] * d(tau)
because n*o*s is tau (optical density). However Integrating along an increment of path is far more intuitive that integrating through an increment of optical density. Any this completely loses track of the idea that you are merely accounting for emission and absorption along a path.
-- "Ben: By definition, when someone refers to an optically-thick layer of atmosphere, they are postulating a layer that emits like a blackbody."
No, this isn't right. An optically-thick layer has absorptivity close to 1 at *some* frequencies. In contrast, a blackbody has absorptivity close to 1 at *all* frequencies.
-- "There is no such thing as an optically-thick layer on Earth"
Most clouds you see in the sky are optically thick in the visual range; you can't see through them. Humid air is optically thick in relevant amounts (~100s of meters at STP) at the most-absorbing frequencies of H2O. Yes, there are optically thick layers on Earth.
-- "These abominations arise because climate scientists want to start the discussion with familiar blackbody radiation, which by the derivation of Planck's Law is radiation where emission and absorption are in equilibrium"
No, climate scientists absolutely do not treat greenhouse gases as blackbodies. Even the Earth's surface isn't treated as a blackbody; the albedo is > 0. The whole basis of our understanding of greenhouse gases are that they *aren't* blackbodies; that their absorptivity varies based on wavelength. (And of course absorptivity varies by the amount of material, but that's true for everything, not just gases).
So if the atmosphere gets ”thicker” the radiation (on average) will leave the atmosphere for space at a higher altitude. If the temp is lower at this higher altitude, less energy leaves earth atmosphere. Right?
However, this is true if a thicker atmosphere is one that contains a more GHGs. AND if the bulk of the photons escaping to space are emitted from altitudes where temperature is falling with increasing altitude. Then less energy will leave a planet when more GHGs are present. Most of the photons escaping to space from the Earth are emitted from the troposphere.
Some people might say that the "thickness" of an atmosphere is determined by how low gravity pulls the average gas molecules toward the surface. However, I presume you aren't referring to this kind of thickness.
Thomas: A better reply to Robert Hissey's claim that no photons leave Earth for space in the 14-16 um band is to look at a spectrum of radiation leaving earth for space by a spectrometer on the Nimbus 4 spacecraft in Figure 8.3 of Grant Petty's inexpensive, but invaluable textbook "A First Course in Atmospheric Radiation". The radiance in the CO2 band is about half to one-third that at the wavelengths the Earth emits most strongly. These radiances are often converted to black-body equivalent temperatures aka "brightness temperature". The brightness temperature is about 220 K roughly the temperature of the atmosphere near the tropopause, the altitude where most of the photons emitted by CO2 and escaping to space originate.
Radiation transfer calculation reproduce most radiative fluxes in our atmosphere with good accuracy. If calculations are acceptable, then go to the MODTRAN calculator for radiation transfer, pick your atmospheric conditions and "look down from 70 km to view the spectrum of what escapes to space.
"The time to theorize is over. Let's have some actual real testing-the basis of science Basically, however, we can posit theories all day. Put where is the actual evidence or proof? It would have to be to measure the transmissivity of 400 ppm Co2 against 800 ppm CO2, in the same lab with the same equipment.
First we can't raise the concentration of CO2 in the atmosphere to 1000 ppm for a decade or so to figure how much hotter it will get and go back to 300 or 400 ppm. We are ALREADY conducting an experiment with our [only] planet by raising CO2 by burning fossil fuels and we'd like to know how that experiment will turn out if we stop at 500 ppm, 600 ppm, 700 ppm and so on. So far, temperature has been rising about 0.2 degK per decade for the last half century. Unfortunately CO2 isn't the only thing that has been changing. Aerosols were increasing until the early 2000s and negated some warming by reflecting some SWR to space. If we quantify all of this other influences in terms of how much they slow down (or speed up) radiative cooling to space - this is called forcing - temperature has risen about 0.4 K/(W/m2) of forcing. A doubling of CO2 is about 3.5 W/m2. However some of the heat from forcing is accumulating in the deep ocean, delaying surface warming. There will be more warming associated with the current forcing in the future. So we are already doing the experiments with rising CO2 and analyzing the results, but Robert isn't aware this is happening.
More than a decade ago, I fantasized about shining a huge variable wavelength laser through the atmosphere to a detector on a spacecraft and recording the transmission of thermal IR through the atmosphere at all wavelengths. After a few years of reading SoD's blog, it finally penetrated my thick skull that all of the necessary experiments with CO2 had been done and the key parameters from those experiments (which also been repeated with increasing sophistication) had been recorded in the HITRAN database where anyone can use them. Our host, SoD, actually wrote his own compute program to use of that data to calculate transmission through our atmosphere with different amounts of CO2 and water vapor in it and reported the results in his old blog. We've done all of the basic experiments with CO2 that needed to be done long ago. and the results were used in the space program to calculate radiative cooling of spacecraft re-entering the atmosphere long before global warming was a "thing". However, Robert is throwing a tantrum saying he hasn't seen data from the experiments he wants to see and this stuff can't possibly be taken seriously until they are done his way. And given that all humans struggle with confirmation bias, he forgets important information that conflicts with his deeply held belief that GHG mediated warming is a fraud. (I would forget also forget important problems with the consensus if I didn't already believe there were problems). However, radiation transfer calculations are not a problem.
The basic ideas you present and claim “prove the greenhouse effect” are all basic nonsense.
1. “The temperature of the atmosphere decreases as you go up in altitude”. False, the temperature of the atmosphere increases as you go down in altitude. An important distinction.
2. “ Gases absorb radiation at various wavelengths, depending on the gas in question. The higher the concentration of the gas, the more the absorption”. False, all matter absorbs energy at all frequencies. In Earths atmosphere certain gases have certain “finger print” absorption bands relating to their phase change temperatures. This identifies them in the gas mixture we call the atmosphere and this is what is depicted in the spectral graph above. However, no amount of emission of 15μm radiation from CO2 can heat a single molecule in the troposphere.
3. “ Gases emit radiation at various wavelengths. The higher the temperature of the gas, the more the emission. The higher the concentration of the gas, the more the emission”. Again false, gases emit radiation at all frequencies depending entirely on temperature. With a finite source of energy, more molecules equates to less emission per molecule.
None of these corrections affect the physics of the atmosphere. Rather, they serve to answer some of the obvious glaring questions generated by the silly science of Malthusian “greenhouse gas effect” hypotheses.
John Tyndall, who was a close associate of Galton, Huxley and various other Malthusians and Eugenicist’s, published a set of memoirs titled “Molecular Physics in the Domain of Radiant Heat”. This work is pretty much the entire basis for the “greenhouse gas hypothesis”. In the title and throughout the whole tediously fallacious record of what amounts to nothing more than a set of parlour tricks, he continuously refers to “radiant heat”. Unbeknown to Tyndall at the time he produced this deliberate deception, “radiant heat” did not actually exist. It has since been well and truly established, by real scientists doing real science, that there is radiation and there is heat. Heat is not radiation and radiation is not heat. There is no such thing as “radiant heat”. Also unbeknown to Tyndall at the time was that heat is a specific type of energy and is a vector with direction from hot to cold and cannot be “trapped”. The moment it is trapped it stops being heat and changes into another type of energy as in the case of phase change.
The ambiguity of terms like “radiant heat’ have no place in science. Neither do terms such as “greenhouse effect”.
"1. “The temperature of the atmosphere decreases as you go up in altitude”. False, the temperature of the atmosphere increases as you go down in altitude. An important distinction."
Thanks for clarifying your thought process for everyone. I'm not alone in expecting the rest of your arguments and points to be of a similar quality.
The main problem with your claims and the overall GHG hypothesis Steve, is that nothing resolves to a satisfactory conclusion. Instead every aspect of the hypothesis generates more questions than it answers. That really ought to be a clue to anyone with a pragmatic approach in any field, that they are wrong, don’t you think?
So let’s start with your insightful critique of my first correction to your “proof of the greenhouse effect”. Please give a cogent explanation as to why the normal lapse rate of 6.5° C/km breaks down above the effective emission height. Let’s start with that and see how you get on shall we?
Like I said, it is an important distinction that if you are unable to grasp, you really have no place commenting on anything concerning the Earth’s climate. In much the same way as commenting on climate variability without reference to Solar cycles. Solar cycles have been studied by humans for their effect on climate for more than 6000 years, who are you to ignore them?
So you have no explanation for why the normal lapse rate breaks down above the effective emission height then? That is why you are unable to grasp the simple concept that the atmospheric lapse rate is measured down from the effective emission height and not as you have stated, hilariously, up from the ground.
Like I said, if your hypothesis generates more questions than it answers, as is the case with the silly GHG hypothesis, it’s wrong!
All of these models assume the truth of the hypothesis that adding more CO2 to the atmosphere will increase ir absorption and thus raise the temperature. Two facts are obviously ignored. First, no one has ever put forward a proof of this hypothesis! Could it be that the hypothesis is false? Is the entire war on fossil fuel based on an unproven hypothesis?
Second, the 1991 NASA project on the Infra-red transmission/absorbtion of the atmosphere in 1991 shows total absorption of all the energy in the only band where CO2 is effective is already cleaned of all energy. True, this information was kept hidden until 1992 and still recieves no publicity. Thus, more CO2 can not absorb any energy, so does not affect gloal warming. The climate sensitivity to CO2 addition is zero. All the models are thus fatally corrupted.
The arguement is made that doubling the CO2 will cause crowding, and thus broaden the band. No citation or reference. An analogy. A quart of beans is like 2,500 beans. Present atmosphere has one black bean. Doubling is adding 1 more black bean. Now 2 black beans in a quart jar of 2,500 beans is not very crowded.
I uncovered the NASA data at "Nasa Technical Memorandum 103957, Appendices E and F", all 100 pages of it. It is also available on Kindle. The salient 15 micron part is available in a more convenient form, with discussion, in my little booklet on Kindle "Carbon Dioxide-Not Guilty". This has been searchable for a year now. It is 99c and in interest of clarity, I get 6c each! It is also available as a free PDF to anyone who sends me an e-mail address.
The troposphere is defined by molecules with a temperature of -60 °C and above. This is why absorption and emission of 15μm radiation has no effect on the temperature of the troposphere.
The so called “greenhouse effect” hypothesis is pure pseudoscience and easily debunked.
* The Effective emission height. The true emission surface of the atmosphere @ -18 °C
* PV = nRT
* Normal adiabatic lapse temperature of 6.5 °C/km
In any radiosonde data, locate the altitude of the effective emission height which will be @ -18 °C. Predict the near ground temperature using the normal lapse rate 6.5 °C/km, confirm with empirical data and et viola, you have proven that it is possible to describe any part of the atmospheric temperature profile, below the effective emission height, without any reference to the so called “greenhouse gases” whatsoever. Greenhouse gas hypothesis easily debunked!
When an hypothesis can be completely ignored without effecting the very process it is supposed to be responsible for, it is by definition, pseudoscience.
Sure, the Greenhouse effect of CO2 is real, but to assume that the effect continues indefinitely is unwarranted. If your corn gowns to 6 ft in 3 months, it doesn't mean it will grow to 12 ft in 6 months. The 14-16 micron band is already totally absorbed at well below the present 400ppm.
Since the band width is determined by the 15mm spike and the Doppler effect, doubling CO2 makes no difference.
Why do activists shy away from experiments to prove their Hypothesis? Perhaps they are not confident of the outcome.
Refer: NASA Technical Memorandum 103957 Appendices E and F. Lord, 1992
"the Greenhouse effect of CO2 is real, but to assume that the effect continues indefinitely is unwarranted."
With increasing CO2 the temp does continue indefinitely as long as CO2 concentration in the atmosphere continues to go up, but the CO2 concentration/temp curve is logarithmic so its not a one to one increase.
What do you make of the experiment I provided above. It shows clearly that CO2 has an impact from at least 13um through to 18um, and that the effect is not saturated near the edges of the band.
I think the effect seen there is "smearing", due to the coarseness of the instrumentation used in NASA Nimbus 4. (That seems to be the source of the "actual", I don't know the source of the "theoretical") Compare the "Theoretical" curve with the NASA Lord data, which shows the total extinction in the 14-16 micron band and very sharp edges. A condensed version of this data had been shown on the web site of the Gemini IR Astronomy project, but since taken down. It still can be found on an unattended page there. A copy can be found on page 18 of my little booklet "Carbon Dioxide-Not guilty". Also a plot showing a 1% increase in absorption by doubling from 400-800ppm. The booklet is available on kindle for 99c, or as a free PDF to anyone sending me their email. bobhisey at comcast.net.
The key word is significant. The Doppler effect is taken to be a bell curve, so in theory extends to infinity. But not in practice, where one assumes a cut off at, say 3 sigma. Or there is little difference between 99% extinction and 100%. Our instrumentation foes not catch the last few elusive photons.
Accuracy is more important than precision in determining actions.
The only way to satisfactorily conclude this discussion is a test of actual absorption at 400 and 800 in the same lab with the same equipment and conditions.
There are measurements in the literature from 1920-1970, but none are the above. They seem to concentrate on the two shorter wavelength bands.
I think you might enjoy my little booklet, I hope you get it.
I don't think "smearing" is an instrumentation issue: pressure broadening is a real physical phenomenon (or: set of phenomena).
Absorption/emission spectra broaden at higher atmospheric pressures. Which means the absorption/emission spectra of CO2 at sea level are different from at 10k feet, 20k feet, 50k, etc.
We get some interesting results from this. For instance, at higher altitudes, there's less overlap between H2O's and CO2's bands.
Hi
Smearing is my worrd for the effect of the precision of the instruments. Take CO2 at 15 microns, band width 2 microns. If the instruments precision is say 5 microns, it will never show zero, as it will still be influenced by the lower absorptions outside the 14-16micron band.
The measurement would start being influenced by that band at 21 microns and extending to 8 microns. I.E. the 2 micron sharp band would be "smeared out" to some 13 microns.
I have no knowledge of the presicion of the instrumentation in the actual satellite. But since it does not show total absorption at 15 microns, it must be less precise than 2 microns. That makes sense as it would be difficult, and very expensive., to have really precise Laboratory in a satellite. One could get an estimate back calculating from the shown curve. See the detailed NASA data at Nasa Technical Memorandum 103957. Or a handier form in my little booklet "Carbon Dioxide - Not Guilty", 99c at Kindle amazon, or free to anyone who sends me an email address.
Band width is determined by the Doppler effect. A bell shaped curve, with the tails cut off beyond 2 to 3 sigma.
Various methods of calculating how fast the 14-16 band is absorbed, agree that it will be totally (99.9%) within 2 to 3 thousand feet. So pressure effect is minimal.
My biggest problem is the lack of laboratory data to prove/disprove the assumtption that doubling CO2 from400 ppm to 800ppm woudl cause a very substantial increase of heat absorbed by the CO2. There is nothing in the literature even close to such an experiment.
Here we are, spending trillions on an unproven assumption!
In science I was taught first form an hypothesis, then prove it, then act on it.
If the spectrometer used had low resolution, how come there are narrow spikes in the center of the ozone and CO2 bands? Answer: the spectrometer used in this experiment is, in fact, high resolution, probably Fourier Transform. The resolution is at least as good as the half-width of the narrowest peak.
In the center of the CO2 band, the absorption near the surface is greater than 99% at path lengths of a meter or so, much, much less than 2 to 3 thousand feet. But the graph depicted is emission, not absorption. The reason you see a valley is that the effective emission altitude increases with increasing absorption and it's colder at higher altitude and the CO2 emits at a lower rate. There is an exception, though. Some of the emission in the center of the valley is generated in the stratosphere where temperature increases with altitude and absorption is minimal. That's why you see a sharp peak at 667 reciprocal centimeters. If the measurement were taken at the tropopause, the bottom of the emission valley would be flat.
The absorption is saturated yes but if the Co2 concentration increases, the altitude from where the radiation leaves the atmosphere increases. With increased altitude comes a lower temperature (if not in the stratosphere). Lower temperature decreases the amount of energy radiated from the stmosphere. The earth warms.
I can not follow your comment. It seems you are saying that radiation leaving the atmosphere originates in the atmosphere, not from the earth. There is no measureable radiation originating in the atmosphere.
Simple physics wins. Established fact, If co2 incresase, the total absorption of the 14-16 micron band occurs at a lower level. In either case, there is no radiation in this band remaining to leave the atmosphere. so no net change in global warming.
Robert,
"There is no measureable radiation originating in the atmosphere"
What do you make of this "measureable radiation" originating in the atmosphere -
https://scienceofdoom.files.wordpress.com/2010/07/dlr-spectrum-antarctica-walden-19981.png
You can find it in this article:
https://scienceofdoom.com/2010/07/24/the-amazing-case-of-back-radiation-part-two/
Do you know Planck's law of emission? Do you believe it? Emissivity and temperature are the factors that affect emission of radiation at each wavelength.
Have you read any textbooks on radiation?
I don't expect coherent answers but other readers who are undecided might get the point.
I am fully aware of plancks law, which is based on black bodies. As a PhD scientist, of course.
Are you? Please refer to "Radiative Heat Transfer" by MichaelF.Modest. The bible
Air or CO2 are not black bodies, far from it. They can be cosidered white bodies. A CO2 molecule energized by a IR photon of the correct wavelength takes about 1second to re-emit it. In that time it has had a billion collisions with O or N atoms where the energy is released in the form of velocity or heat. So it can be thought of as being 1 tenmillionth blackness and the rest white.
We are not supposed to use agruments ad hominem in this discussion.
What do you make of the NASA data showing zero transmission from the atmosphere in this 14-16 micron range. That is, no transmission from the earth or from energized CO2.
This data has been happily in use for 30 years by the IR Astronomers evidencing its reliability. (NASA Technical Memorandum 103957, App. E). Additional evidence is that a green activist high in NASA took the risk and trouble of burying this data where it could not be found by search engines Please share with us your factual basis for not using/trusting this data?
As far as your refence, it appears to show no radiation increment for CO2 in the 14-16micron band. Check the lower graph in Fig 11.
I trust this is coherent enough for you. If not please inform me.
You said: "There is no measureable radiation originating in the atmosphere"
- it is there in the graphic. The measurement is at the surface from an instrument pointing up at the sky measuring radiation.
It matches theory.
I think his point is that there is no measureable radiation from Earth as a whole that originated in the atmosphere. The radiation that does originate in the atmosphere ultimately gets reflected back to the ground, rather than pass through the atmosphere. The plots in NASA Technical Memorandum 103957, App. E (https://ntrs.nasa.gov/citations/19930010877 -- see plots #16-18 on p. 113-115) support the proposition that no energy from the 14-16 um band is transmitted through the atmosphere. (I'm not arguing for or against his point, just trying to explain it as I understand it.)
Robert Hissey wrote at https://scienceofdoom.substack.com/p/natural-variability-attribution-and-a70/comments#comment-17367039 and I'm helping our host move the conversation here:
"My statements apply only to the 14-16 micron band. Photons in this band have been shown to never reach space. That is, the absorbance by CO2 and transference to heat in the atmosphere vastly outweighs the occasional re-emittance of a photon of that wavelength."
Frank: Photons in this band are emitted to space by our planet all the time. Experimentally we observed them from space continuously. However the photons that are reaching space are not the ones that are emitted by the surface. They are emitted from 10 km above the surface or 20 km above the surface. At 15 km above the surface, we are above 90% of the atmosphere and the mean free path between emission increases 10-fold for photons absorbed by CO2 and far more for photons absorbed by water vapor since the atmosphere gets much drier with altitude.
Your use of the phrase "re-emittance" suggests a possible misunderstanding. Absorbing a photon of thermal IR radiation produces an excited vibrational, rotational or a combinations of vibrational+ rotational excited states. (That is why the 15 um line for CO2 can be resolved into dozens of nearby lines under some conditions). The excited vibrational state has a half-life of about 1 second and collisions occur about 10^9 times a second near the surface, though not every collision is capable of relaxing an excited state. Therefore re-emission of an absorbed photon from the excited state that produced it is not a significant process in the troposphere and lower stratosphere where all the important absorption and emission appear. The energy from the excited state end up increasing the velocity of the colliding gas molecules, increasing their temperature. This process is sometimes called "thermalization".
Essentially all of the excited states that emit photons are created by "collisional excitation". Collisional excitation produces a Boltzmann distribution of energy among all possible excited states (with exp(-E/kT) fewer molecules with in an energy state E above ground state. When deriving Planck Law (and the Schwarzschild equation) we assume a Boltzmann distribution of energy states. Therefore Planck's Law has mathematics that ensures that it needs to be at least 1000 degK to emit a significant number of visible photons, but the atmosphere and surface emit "thermal IR photons" at 190-310 degK. When a Boltzmann distribution of excited states exists (and energy is being exchanged by collisions much faster than by photons of any other process), we say the atmosphere is in "local thermodynamic equilibrium". (This does not mean emission and absorption are in equilibrium). Normally we need to heat something to several thousand degK to get it to emit a significant amount of visible light, but we have invented some devised that allow us to create a lot of excited states without collisional excitation, where a Boltzmann distribution of energy states does not exist and visible light can be emitted without high temperature. LED, lasers, fluorescent light bulbs and microwave ovens are devices that create a non-Boltzmann distribution with far more excited states than normal.
Hey Frank, back on "Natural Variability, Attribution and Climate Models #5", you said:
"There is a fundamental problem with emission of radiation when it is presented as emission of blackbody radiation in basic undergraduate courses" - and you go on to talk about emissivity.
But I'm looking at "Principles of Planetary Climate", which is a very popular textbook for introductory climate science classes, and emissivity vs blackbody is addressed in chapter *3* That is: pretty early in the overall arc of study for any serious student of climate science. The book goes on to immediately discuss Kirchoff's Law of Radiation.
It's completely, 100% fine to point out that atmospheres don't actually absorb/emit blackbody radiation (which would include unit emissivity/absorbtivity). But does this really make for a serious critique of how climate science is taught in college programs, when introductory texts also address this point rather early?
Here's where I'm coming from: in many of the internet discussions I've seen on this subject, I see skeptics and deniers say "well, what about X?!? Have scientists addressed *that*?" and you find that "X" is some point of science that scientists talked out a century ago - the effect of water vapor is a good example. Or, just more generally, it often seems like many "skeptics" never picked up textbooks on the subject to actually study deeply and learn what the scientists are saying. They're operating based on what they *heard* from other skeptics that scientists are saying - and there's a disconnect between what the skeptics understand the science to be, versus the *actual* state of the science as taught in universities and accepted by leaders in the field.
And then I have kinda gotten frustrated by that disconnect; it seems like laziness on the part of the skeptics: if you're going to criticize a field, get educated about it first.
So this conversation has drawn *lightly* on that frustration, 'cause it *feels* like you're doing a little bit of the same. When you say that CO2 particles' extra radiation-emission makes up for their extra radiation-absorption, it seems like you're missing some understanding of the basic mechanics of radiative optics. I might be misunderstanding your position - but, regardless, this is where I'm currently coming from.
Physicists have lousy explanations for emissivity and most climate scientist as busy at explaining physics. What is emissivity? Well, the emissivity of many metals can be changed by polishing the surface or a thin coating of oxide on the surface. Emissivity therefore must be a phenomena that develops at surfaces or interfaces. Emissivity equals absorptivity (reflectivity) which is a phenomena that occurs when incoming radiation encounters a surface - another surface phenomena. In the case of water, it is easy to think in terms of incoming radiation being partially reflected outward by the surface and radiation traveling through water being partially reflected inward at the surface. That would explain why water has an emissivity less than 1 (and which depends modestly on wind disturbing the surface.) Gases have no surface, so my hypothesis is that they have an emissivity of 1. Does blackbody radiation travel through solids and get partially reflected as it exits the surface resulting in an emissivity less that 1? That's my explanation. And the same fraction of radiation coming in from the air is reflected at the same surface. Beware: I can't find this explanation anywhere, it is self-"taught". People talk about energy traveling through solids in terms of phonons (quasiparticles of sound or vibration in a solid lattice) not photons or electromagnetic waves. This is a subject I haven't even explored. What does solid-state physics tell us about what happens when a phonon encounters a surface? Does it get reflected or result in the emission of a photon? Liquids like water don't have a lattice and no one has a problem imagining photons traveling through them - unless we talk about mercury metal.
"What is emissivity? Well, the emissivity of many metals can be changed by polishing the surface or a thin coating of oxide on the surface. Emissivity therefore must be a phenomena that develops at surfaces or interfaces."
*Whoa*, there!
Just because surfaces are often optically active doesn't mean that *only* surfaces are optically active. The interior of materials can be optically active, too! Optical phonon modes inside a crystalline material can catch/emit light, individual molecules can absorb light corresponding to an electron gap (this is how many dyes work), or crystalline defects can alter the local ev gap. And there are many, many other ways for atoms to couple for oscillating electrostatic fields -- which makes them optically active.
Surfaces are *absolutely* not required for photons to be absorbed or emitted. This is flat wrong.
Emissivity/absorptivity approaches 1 at some wavelength simply when there are enough optically-active material to absorb close to all of the incoming light at that wavelength. How much material this takes depends on the type of material (obv), and things like metals absorb and reflect easily because of the lack of band gap, because there are many free electrons that are available to absorb the incoming electromagnetic energy and there is no gap between the valence and conduction bands. Gases, by constrast, don't have the same free electrons and have specific band gaps, making them optically active only at specific frequencies (setting aside pressure broadening or similar effects). And gases are likewise much less dense, making their absorptivity / volume rather lower.
"People talk about energy traveling through solids in terms of phonons (quasiparticles of sound or vibration in a solid lattice) not photons or electromagnetic waves."
Phonons can be optically active! Meaning, light can be absorbed, turned into an optical phonon, which then is transmitted through the material, and then the phonon losslessly turns back into a photon on the other side. Or maybe the photon passed through without being absorbed at all - this also happens. (Or a mix of the two).
The emissivity/absorptivity of a gas varies with wavelength and somewhat with pressure. But I don't think it can ever be equal to 1. That would imply that every photon that came within the effective radius of the molecule would be absorbed. I don't believe that's true. The absorptivity/emissivity of a molecule can be high, but the emitting area is small. That's why you need lots of them.
DeWitt: Nice to hear from you again. Dense (non gaseous materials have an emissivity usually have an emissivity less than unity. For some metals, emissivity can be much less than unity. No matter how thick a layer of polished copper (emissivity 0.04) may be, its emission of thermal IR at 300 K can never exceed 0.04*o*300^4 according to the Stefan-Boltzmann Law.
Now let's consider CO2 molecules. As you say, their emitting are is small, and we need many of them to get much emission. So let's cram those CO2 molecules next to each other so tightly they are about as close as copper atoms in solid. That will give us lots of collisional broadening. The easies place to imagine this happening near the surface of Venus. Will the gas emit the full o*T^4, or does the gas have an innate emissivity that limits how much radiation can be emitted from a layer to something less that o*T^4 - even when we make that layer as thick as we want?
Thickening a layer of polished copper doesn't increase the number of photons because emissivity less than unity is a phenomena that develops at the surface and affects emission and absorption equally. If we roughen the surface of the copper, the emissivity and absorptivity go up. (This may involve surface oxidation). I first learned to think of emissivity as a phenomena associated with the surface of a material from comments your made years ago. Gases have no surface and therefore should emit o*T^4 when enough gas is present to set up an equilibrium between emission and absorption - which Planck used to devise his law.
Now, it may not be sensible apply the term emissivity to a gas when we probably can't do an experiment to measure it and I need a thought experiment involving very non-ideal CO2 in the atmosphere of Venus to explain my rational.
Yes, Ben. Many skeptics are lazy and don't know about subjects like radiation transfer. When they come across something they don't understand, the simple answer is that there must be a conspiracy to hide the fundamental flaw in climate science they have discovered. The idea of a conspiracy involving the fundament physics of radiation interacting with radiation is absurd.
Are there conspiracies among climate scientists not to talk about weaknesses of climate models and the possibility that climate sensitivity might be on the low end of the old 1.5-4.5 K/doubling? Probably. At least one climate scientist has admitted not being willing to talk publicly about some controversial issues and problems because "deniers" will seize on these problems and exaggerate them on FOX News. In a talk on Youtube, a modeler confessed that all climate models produce far too few marine boundary layer clouds, the clouds that reflect SWR without greatly reducing OLR, the clouds that cool the planet the most. I haven't found this in any papers. None of these problems mean that rising GHGs don't warm the planet, just that they might warm the planet modestly less than expected. Skeptics usually don't care much about the possibility of modest reductions in climate sensitivity; they prefer to blow up the whole idea. Global warming is a hoax.
Ben asked: "When you say that CO2 particles' extra radiation-emission makes up for their extra radiation-absorption, it seems like you're missing some understanding of the basic mechanics of radiative optics. I might be misunderstanding your position - but, regardless, this is where I'm currently coming from."
Fundamental understanding of radiation transfer is contained in Schwarzschild's Equation for Radiation Transfer. This equation predicts how radiation is changed as it travels through an atmosphere of absorbing/emitting molecules with a given altitude-dependent composition and temperature profile. The user needs to specify the amount of radiation entering from one direction and where it leaves. [More fundamentally the physics of radiation transfer starts with Einstein coefficients for absorption, emission, and stimulated emission of photons and energy levels in molecules, and then adds mechanisms of line broadening. However, if you start with absorption coefficients and other spectral information on GHGs that can be measure in the laboratory, you can start with Schwarzschild's Equation (assuming local thermodynamic equilibrium exists and that stimulated emission is negligible, both of which are true where most absorption and emission occurs).
Schwarzschild's Equation predicts that upwell radiation from the surface is reduced from the about 390 W/m2 of blackbody radiation emitted by the surface to 240 W/m2 by the time radiation reaches space. With doubled CO2, only about 236.5 W/m2 will reach space, a 1.5% reduction. So doubling the number of photons emitted and absorbed by doubling the number of CO2 molecules has - to a first approximation - no impact on radiative cooling to space. Instead of doubling absorption on the way to space, emission from doubled CO2 replaces 98.5% of the additional photons being absorbed.
Here is an intuitive way of looking at the problem: Consider a layer of atmosphere somewhere above the ground. The CO2 molecules emit equal number upwards and downwards, so doubling CO2 merely sends twice as many each direction, which doesn't change speed up or slow down radiative cooling to space. Now consider the upwelling and downwelling radiation entering this layer. CO2 absorbs a certain FRACTION of the radiation incoming from each direction. If the upwelling radiation from below - emitted from where it is warmer - is more intense than the downwelling radiation from above - emitted from where it is colder - THEN more photons disappear from the upwelling flux than the downwelling flux. This slows radiative cooling to space. Now, if you are talking about the wavelength that is absorbed most strongly by CO2 and where 90% of the incoming photons are absorbed within one meter and replaced with newly emitted photons, the upwelling and downwelling photons were emitted where the temperature is basically the same and the intensity of these fluxes will be identical and have blackbody intensity. However, if you move to the shoulder of the CO2 absorption band, where the average photon might travel 1 km between emission and absorption, the temperature difference will be 2*6.5 degK and (if my calculations are correct), the upward flux might be 43 W/m2 stronger than the downward flux from this temperature difference. This is why the outward flux of radiation decreases from 390 W/m2 at the surface to 240 W/m2 at the TOA, while the downward flux increases from 0 W/m2 at the TOA to 333 W/m2 at the surface. And why doubling CO2 slows radiative cooling to space only a little bit.
You can see how doubling CO2 effects upward radiation transfer through the atmosphere at different wavelengths at our host's old blog in Figure 15 and 16 and in a lower resolution Figure in Wikipedia:
https://scienceofdoom.com/2011/03/12/understanding-atmospheric-radiation-and-the-“greenhouse”-effect-–-part-nine/
https://en.wikipedia.org/wiki/Radiative_forcing#/media/File:ModtranRadiativeForcingDoubleCO2.png
Notice that when climate scientist say CO2 traps heat in the atmosphere (by absorption), they are grossly simplifying.
“ Notice that when climate scientist say CO2 traps heat in the atmosphere (by absorption), they are grossly simplifying.”
Wrong! They are not oversimplifying at all. They are talking pure nonsense. No substance “traps heat”. To claim otherwise simply means you don’t know what heat is. Radiation is not heat. 15μm radiation has a corresponding temperature of -80 °C. The troposphere is defined by molecules with a temperature of -60 °C and above. Absorption and emission of 15μm radiation by CO2 cannot heat any molecules in the troposphere.
"The latter case is the one that is always correct, but if you stack enough optically thin layers on top of each other, they will eventually absorb enough of the radiation emitted by other layers that they will emit radiation like a blackbody"
Point: optically-thick layers will generally not emit or absorb like a blackbody.
For an optically-thick layer, the absorptivity/emissivity *at some frequencies* will be close to 1, but there will still also be frequencies where the absorptivity/emissivity is much less than 1. That's what make these not-a-blackbody.
Blackbodies absorb indiscrimately and vary in emission only according to temperature, while optically-thick atmospheres will still preferentially emit/absorb some frequencies over others.
Ben: By definition, when someone refers to an optically-thick layer of atmosphere, they are postulating a layer that emits like a blackbody. There is no such thing as an optically-thick layer on Earth. You'll find other people who say that the emissivity of an optically thin layer is less than 1. These abominations arise because climate scientists want to start the discussion with familiar blackbody radiation, which by the derivation of Planck's Law is radiation where emission and absorption are in equilibrium.
Schwarzschild's equation is mentioned on p 190 of Principles of Planetary Climate, but you will find nowhere that it says radiation transfer in a non-scattering atmosphere is calculated using this equation. The version on p 190 is meaningless to me. There are much more intuitive (for me) versions of this equation. The incremental change in the spectral intensity (dI) of radiation of a given wavelength as it travels an incremental distance (ds) through an atmosphere is caused by emission and absorption from molecules along that path:
dI = emission - absorption
dI = n*o*B(lambda,T)*ds - n*o*I*ds
where: n is the density of absorbing/emitting molecules
o is the absorption cross-section at the wavelength of interest.
B(lambda,T) is Planck's function
and I is the spectral intensity of the radiation entering the increment of distance.
The absorption term on the right should be familiar from Beer's Law. Schwarzschild's equation simplifies to Beer's Law when absorption is much greater and emission. This is the case in a spectrophotometer, which uses a powerful light source to overwhelm emission. The emission term on the left is formulated exactly the same way as the absorption term except the emission cross-section is o*B(lambda,T), which is true when local thermodynamic equilibrium exists. When dI is zero, I = B(lambda,T) and we are discussion radiation of blackbody intensity where emission is balanced by absorption.
Many discussions iof Blackbody radiation gnore the fact that Planck's law gives the spectral intensity of radiation traveling outward from a point, and simply show the formula for the flux of blackbody radiation emitted perpendicular to a plane after integration over a hemisphere (which adds a factor of pi to the formula). We can simply Schwarzschild's equation with a similar trick by considering only the vector components of radiation transfer perpendicular to the planet's surface. They are the only ones that warm and cool the planet. The horizontal components cancel. This replaces ds with dz. This is called the two-stream approximation, and allows us to think in terms the changes in a upwelling flux and downwelling flux.
Now n, o, T and I are all functions of z and should be written n(z), T(z), I(z) and o(lambda,z). And you have to numerically integrate Schwarzschild's equation over a path (say from the surface to space) and overall relevant wavelengths and in practice over all angles in a hemisphere.
PierreHumbert and everyone else always always "simplifies" to:
dI = [B(lambda,T) - I] * d(tau)
because n*o*s is tau (optical density). However Integrating along an increment of path is far more intuitive that integrating through an increment of optical density. Any this completely loses track of the idea that you are merely accounting for emission and absorption along a path.
-- "Ben: By definition, when someone refers to an optically-thick layer of atmosphere, they are postulating a layer that emits like a blackbody."
No, this isn't right. An optically-thick layer has absorptivity close to 1 at *some* frequencies. In contrast, a blackbody has absorptivity close to 1 at *all* frequencies.
-- "There is no such thing as an optically-thick layer on Earth"
Most clouds you see in the sky are optically thick in the visual range; you can't see through them. Humid air is optically thick in relevant amounts (~100s of meters at STP) at the most-absorbing frequencies of H2O. Yes, there are optically thick layers on Earth.
-- "These abominations arise because climate scientists want to start the discussion with familiar blackbody radiation, which by the derivation of Planck's Law is radiation where emission and absorption are in equilibrium"
No, climate scientists absolutely do not treat greenhouse gases as blackbodies. Even the Earth's surface isn't treated as a blackbody; the albedo is > 0. The whole basis of our understanding of greenhouse gases are that they *aren't* blackbodies; that their absorptivity varies based on wavelength. (And of course absorptivity varies by the amount of material, but that's true for everything, not just gases).
So if the atmosphere gets ”thicker” the radiation (on average) will leave the atmosphere for space at a higher altitude. If the temp is lower at this higher altitude, less energy leaves earth atmosphere. Right?
Thomas: The simple answer is: You are right.
However, this is true if a thicker atmosphere is one that contains a more GHGs. AND if the bulk of the photons escaping to space are emitted from altitudes where temperature is falling with increasing altitude. Then less energy will leave a planet when more GHGs are present. Most of the photons escaping to space from the Earth are emitted from the troposphere.
Some people might say that the "thickness" of an atmosphere is determined by how low gravity pulls the average gas molecules toward the surface. However, I presume you aren't referring to this kind of thickness.
Thomas: A better reply to Robert Hissey's claim that no photons leave Earth for space in the 14-16 um band is to look at a spectrum of radiation leaving earth for space by a spectrometer on the Nimbus 4 spacecraft in Figure 8.3 of Grant Petty's inexpensive, but invaluable textbook "A First Course in Atmospheric Radiation". The radiance in the CO2 band is about half to one-third that at the wavelengths the Earth emits most strongly. These radiances are often converted to black-body equivalent temperatures aka "brightness temperature". The brightness temperature is about 220 K roughly the temperature of the atmosphere near the tropopause, the altitude where most of the photons emitted by CO2 and escaping to space originate.
Radiation transfer calculation reproduce most radiative fluxes in our atmosphere with good accuracy. If calculations are acceptable, then go to the MODTRAN calculator for radiation transfer, pick your atmospheric conditions and "look down from 70 km to view the spectrum of what escapes to space.
https://climatemodels.uchicago.edu/modtran/
Robert Hissey wrote at https://scienceofdoom.substack.com/p/natural-variability-attribution-and-a70/comments#comment-17367039 and I'm helping our host move the conversation here:
"The time to theorize is over. Let's have some actual real testing-the basis of science Basically, however, we can posit theories all day. Put where is the actual evidence or proof? It would have to be to measure the transmissivity of 400 ppm Co2 against 800 ppm CO2, in the same lab with the same equipment.
First we can't raise the concentration of CO2 in the atmosphere to 1000 ppm for a decade or so to figure how much hotter it will get and go back to 300 or 400 ppm. We are ALREADY conducting an experiment with our [only] planet by raising CO2 by burning fossil fuels and we'd like to know how that experiment will turn out if we stop at 500 ppm, 600 ppm, 700 ppm and so on. So far, temperature has been rising about 0.2 degK per decade for the last half century. Unfortunately CO2 isn't the only thing that has been changing. Aerosols were increasing until the early 2000s and negated some warming by reflecting some SWR to space. If we quantify all of this other influences in terms of how much they slow down (or speed up) radiative cooling to space - this is called forcing - temperature has risen about 0.4 K/(W/m2) of forcing. A doubling of CO2 is about 3.5 W/m2. However some of the heat from forcing is accumulating in the deep ocean, delaying surface warming. There will be more warming associated with the current forcing in the future. So we are already doing the experiments with rising CO2 and analyzing the results, but Robert isn't aware this is happening.
More than a decade ago, I fantasized about shining a huge variable wavelength laser through the atmosphere to a detector on a spacecraft and recording the transmission of thermal IR through the atmosphere at all wavelengths. After a few years of reading SoD's blog, it finally penetrated my thick skull that all of the necessary experiments with CO2 had been done and the key parameters from those experiments (which also been repeated with increasing sophistication) had been recorded in the HITRAN database where anyone can use them. Our host, SoD, actually wrote his own compute program to use of that data to calculate transmission through our atmosphere with different amounts of CO2 and water vapor in it and reported the results in his old blog. We've done all of the basic experiments with CO2 that needed to be done long ago. and the results were used in the space program to calculate radiative cooling of spacecraft re-entering the atmosphere long before global warming was a "thing". However, Robert is throwing a tantrum saying he hasn't seen data from the experiments he wants to see and this stuff can't possibly be taken seriously until they are done his way. And given that all humans struggle with confirmation bias, he forgets important information that conflicts with his deeply held belief that GHG mediated warming is a fraud. (I would forget also forget important problems with the consensus if I didn't already believe there were problems). However, radiation transfer calculations are not a problem.
I'm moving a comment from "Natural Variability, Attribution and Climate Models #11" - https://scienceofdoom.substack.com/p/natural-variability-attribution-and-f99
---
Will Pratt
Writes The Perpetual Lightbulb
But natural climate variability shows clear unequivocal signs of patterns that are directly attributable to solar cycles.
There is absolutely no human signal in the CO2 data let alone climate variability.
You first need to show through experiment that CO2 traps heat. As heat is a vector and cannot be trapped, that’s never going to happen.
The basic ideas you present and claim “prove the greenhouse effect” are all basic nonsense.
1. “The temperature of the atmosphere decreases as you go up in altitude”. False, the temperature of the atmosphere increases as you go down in altitude. An important distinction.
2. “ Gases absorb radiation at various wavelengths, depending on the gas in question. The higher the concentration of the gas, the more the absorption”. False, all matter absorbs energy at all frequencies. In Earths atmosphere certain gases have certain “finger print” absorption bands relating to their phase change temperatures. This identifies them in the gas mixture we call the atmosphere and this is what is depicted in the spectral graph above. However, no amount of emission of 15μm radiation from CO2 can heat a single molecule in the troposphere.
3. “ Gases emit radiation at various wavelengths. The higher the temperature of the gas, the more the emission. The higher the concentration of the gas, the more the emission”. Again false, gases emit radiation at all frequencies depending entirely on temperature. With a finite source of energy, more molecules equates to less emission per molecule.
None of these corrections affect the physics of the atmosphere. Rather, they serve to answer some of the obvious glaring questions generated by the silly science of Malthusian “greenhouse gas effect” hypotheses.
John Tyndall, who was a close associate of Galton, Huxley and various other Malthusians and Eugenicist’s, published a set of memoirs titled “Molecular Physics in the Domain of Radiant Heat”. This work is pretty much the entire basis for the “greenhouse gas hypothesis”. In the title and throughout the whole tediously fallacious record of what amounts to nothing more than a set of parlour tricks, he continuously refers to “radiant heat”. Unbeknown to Tyndall at the time he produced this deliberate deception, “radiant heat” did not actually exist. It has since been well and truly established, by real scientists doing real science, that there is radiation and there is heat. Heat is not radiation and radiation is not heat. There is no such thing as “radiant heat”. Also unbeknown to Tyndall at the time was that heat is a specific type of energy and is a vector with direction from hot to cold and cannot be “trapped”. The moment it is trapped it stops being heat and changes into another type of energy as in the case of phase change.
The ambiguity of terms like “radiant heat’ have no place in science. Neither do terms such as “greenhouse effect”.
Will,
Clearly you have some amazing physics insights:
"1. “The temperature of the atmosphere decreases as you go up in altitude”. False, the temperature of the atmosphere increases as you go down in altitude. An important distinction."
Thanks for clarifying your thought process for everyone. I'm not alone in expecting the rest of your arguments and points to be of a similar quality.
The main problem with your claims and the overall GHG hypothesis Steve, is that nothing resolves to a satisfactory conclusion. Instead every aspect of the hypothesis generates more questions than it answers. That really ought to be a clue to anyone with a pragmatic approach in any field, that they are wrong, don’t you think?
So let’s start with your insightful critique of my first correction to your “proof of the greenhouse effect”. Please give a cogent explanation as to why the normal lapse rate of 6.5° C/km breaks down above the effective emission height. Let’s start with that and see how you get on shall we?
Like I said, it is an important distinction that if you are unable to grasp, you really have no place commenting on anything concerning the Earth’s climate. In much the same way as commenting on climate variability without reference to Solar cycles. Solar cycles have been studied by humans for their effect on climate for more than 6000 years, who are you to ignore them?
Will
You lost me with your ridiculous statement I highlighted.
I'll pass on discussing something about physics with someone who says "-a is false! Instead the answer is -a".
You're either a moron, or someone intelligent who delights in playing stupid word games.
You can find more appreciative, and larger, audiences elsewhere. Claim victory, and move on.
So you have no explanation for why the normal lapse rate breaks down above the effective emission height then? That is why you are unable to grasp the simple concept that the atmospheric lapse rate is measured down from the effective emission height and not as you have stated, hilariously, up from the ground.
Like I said, if your hypothesis generates more questions than it answers, as is the case with the silly GHG hypothesis, it’s wrong!
No wonder you want me to quickly move on, lol!
I'm moving this comment here from "Natural Variability, Attribution and Climate Models #12" - https://scienceofdoom.substack.com/p/natural-variability-attribution-and-469
Robert Hisey
All of these models assume the truth of the hypothesis that adding more CO2 to the atmosphere will increase ir absorption and thus raise the temperature. Two facts are obviously ignored. First, no one has ever put forward a proof of this hypothesis! Could it be that the hypothesis is false? Is the entire war on fossil fuel based on an unproven hypothesis?
Second, the 1991 NASA project on the Infra-red transmission/absorbtion of the atmosphere in 1991 shows total absorption of all the energy in the only band where CO2 is effective is already cleaned of all energy. True, this information was kept hidden until 1992 and still recieves no publicity. Thus, more CO2 can not absorb any energy, so does not affect gloal warming. The climate sensitivity to CO2 addition is zero. All the models are thus fatally corrupted.
The arguement is made that doubling the CO2 will cause crowding, and thus broaden the band. No citation or reference. An analogy. A quart of beans is like 2,500 beans. Present atmosphere has one black bean. Doubling is adding 1 more black bean. Now 2 black beans in a quart jar of 2,500 beans is not very crowded.
I uncovered the NASA data at "Nasa Technical Memorandum 103957, Appendices E and F", all 100 pages of it. It is also available on Kindle. The salient 15 micron part is available in a more convenient form, with discussion, in my little booklet on Kindle "Carbon Dioxide-Not Guilty". This has been searchable for a year now. It is 99c and in interest of clarity, I get 6c each! It is also available as a free PDF to anyone who sends me an e-mail address.
Robert, 15μm radiation has a corresponding temperature of -80 °C. You can confirm that using Wien’s displacement law. https://www.omnicalculator.com/physics/wiens-law
The troposphere is defined by molecules with a temperature of -60 °C and above. This is why absorption and emission of 15μm radiation has no effect on the temperature of the troposphere.
The so called “greenhouse effect” hypothesis is pure pseudoscience and easily debunked.
* The Effective emission height. The true emission surface of the atmosphere @ -18 °C
* PV = nRT
* Normal adiabatic lapse temperature of 6.5 °C/km
In any radiosonde data, locate the altitude of the effective emission height which will be @ -18 °C. Predict the near ground temperature using the normal lapse rate 6.5 °C/km, confirm with empirical data and et viola, you have proven that it is possible to describe any part of the atmospheric temperature profile, below the effective emission height, without any reference to the so called “greenhouse gases” whatsoever. Greenhouse gas hypothesis easily debunked!
When an hypothesis can be completely ignored without effecting the very process it is supposed to be responsible for, it is by definition, pseudoscience.