What If There Was No Greenhouse Effect?
by Roy W. Spencer, Ph. D.
The climate of the Earth is profoundly affected by two competing processes: the greenhouse effect, which acts to warm the lower atmosphere and cool the upper atmosphere, and atmospheric convection (thermals, clouds, precipitation) which does just the opposite: cools the lower atmosphere and warms the upper atmosphere.
To better understand why this happens, it is an instructive thought experiment to ask the question: What if there was no greenhouse effect? In other words, what if there were no infrared absorbers such as water vapor and carbon dioxide in the atmosphere?
While we usually only discuss the greenhouse effect in the context of global warming (that is, the theory that adding more carbon dioxide to the atmosphere will lead to higher temperatures in the lower atmosphere), it turns out that the greenhouse effect has a more fundamental role: there would be no weather on Earth without the greenhouse effect.
First, the big picture: The Earth surface is warmed by sunlight, and the surface and atmosphere together cool by infrared radiation back to outer space. And just as a pot of water warming on the stove will stop warming when the rate of energy gained by the pot from the stove equals the rate of energy loss by the pot to its surroundings, an initially cold Earth would stop warming when the rate at which solar energy is absorbed equals the rate at which infrared energy is lost by the whole Earth-atmosphere system to space.
So, let’s imagine an extremely cold Earth and atmosphere, without any water vapor, carbon dioxide, methane or any other greenhouse gases – and with no surface water to evaporate and create atmospheric water vapor, either. Next, imagine the sun starts to warm the surface of the Earth. As the surface temperature rises, it begins to give off more infrared energy to outer space in response.
That’s the Earth’s surface. But what would happen to the atmosphere at the same time? The cold air in contact with the warming ground would also begin to warm by thermal conduction. Convective air currents would transport this heat upward, gradually warming the atmosphere from the bottom up. Importantly, this ‘dry convection’ will result in a vertical temperature profile that falls off by 9.8 deg. C for every kilometer rise in altitude, which is the so-called ‘adiabatic lapse rate’. This is because rising warm air parcels cool as they expand at the lower air pressures aloft, and the air that sinks in response to all of that rising air must warm at the same rate by compression.
Eventually, the surface and lower atmosphere would warm until the rate at which infrared energy is lost by the Earth’s surface to space would equal the rate at which sunlight is absorbed by the surface, and the whole system would settle into a fairly repeatable day-night cycle of the surface heating (and lower atmosphere convecting) during the day, and the surface cooling (and a shallow layer of air in contact with it) during the night.
The global-average temperature at which this occurs would depend a lot on how reflective the Earth’s surface is to sunlight in our thought experiment. ..it could be anywhere from well below 0 deg F for a partially reflective Earth to about 45 deg. F for a totally black Earth.
So, how is this different from what happens in the real world? Well, notice that what we are left with in this thought experiment is an atmosphere that is heated from below by the ground absorbing sunlight, but the atmosphere has no way of cooling…except in a very shallow layer right next to the ground where it can cool by conduction at night.
Why is this lack of an atmospheric cooling mechanism important? Because in our thought experiment we now have an atmosphere whose upper layers are colder than the surface and lower atmosphere. And what happens when there is a temperature difference in a material? Heat flows by thermal conduction, which would then gradually warm the upper atmosphere to reduce that temperature difference. The process would be slow, because the thermal conductivity of air is quite low. But eventually, the entire atmosphere would reach a constant temperature with height.
Only the surface and a shallow layer of air next to the surface would go through a day-night cycle of heating and cooling. The rest of the atmosphere would be at approximately the same temperature as the average surface temperature. And without a falloff of temperature with height in the atmosphere of at least 10 deg. C per kilometer, all atmospheric convection would stop.
Since it is the convective overturning of the atmosphere that causes most of what we recognize as ‘weather’, most weather activity on Earth would stop, too. Atmospheric convective overturning is what causes clouds and rainfall. In the tropics, it occurs in relatively small and strongly overturning thunderstorm-type weather systems.
At higher latitudes, that convection occurs in much larger but more weakly overturning cloud and precipitation systems associated with low pressure areas.
There would probably still be some horizontal wind flows associated with the fact that the poles would still be cooler than the tropics, and the day-night heating cycle that moves around the Earth each day. But for the most part, most of what we call ‘weather’ would not occur. The same is true even if there was surface water and water vapor…but if we were able to somehow ‘turn off’ the greenhouse effect of water vapor. Eventually, the atmosphere would still become ‘isothermal’, with a roughly constant temperature with height.
Why would this occur? Infrared absorbers like water vapor and carbon dioxide provide an additional heating mechanism for the atmosphere. But at least as important is the fact that, since infrared absorbers are also infrared emitters, the presence of greenhouse gases allow the atmosphere — not just the surface — to cool to outer space.
When you pile all of the layers of greenhouse gases in the atmosphere on top of one another, they form a sort of radiative blanket, heating the lower layers and cooling the upper layers. (For those of you who have heard claims that the greenhouse effect is physically impossible, see my article here. There is a common misconception that the rate at which a layer absorbs IR energy must equal the rate at which it loses IR energy, which in general is not true.)
Without the convective air currents to transport excess heat from the lower atmosphere to the upper atmosphere, the greenhouse effect by itself would make the surface of the Earth unbearably hot, and the upper atmosphere (at altitudes where where jets fly) very much colder than it really is.
Thus, it is the greenhouse effect that continuously de-stabilizes the atmosphere, ‘trying’ to create a temperature profile that the atmosphere cannot sustain, which then causes all different kinds of weather as the atmosphere convectively overturns. Thus, the greenhouse effect is actually required to explain why weather occurs.
This is what makes water such an amazing substance. It cools the Earth’s surface when it evaporates, it warms the upper atmosphere when it re-condenses to form precipitation, it warms the lower atmosphere through the greenhouse effect, and it cools the upper atmosphere by emitting infrared radiation to outer space (also part of the greenhouse effect process). These heating and cooling processes are continuously interacting, with each limiting the influence of the other.
As Dick Lindzen alluded to back in 1990, while everyone seems to understand that the greenhouse effect warms the Earth’s surface, few people are aware of the fact that weather processes greatly limit that warming. And one very real possibility is that the 1 deg. C direct warming effect of doubling our atmospheric CO2 concentration by late in this century will be mitigated by the cooling effects of weather to a value closer to 0.5 deg. C or so (about 1 deg. F.) This is much less than is being predicted by the UN’s Intergovernmental Panel on Climate Change or by NASA’s James Hansen, who believe that weather changes will amplify, rather than reduce, that warming.
Oops! I should have said the drivers of climate are the sun (temperature about 5600K) and H2O in its phases of solid-ice, liquid-water, gas- water vapour.
CO2 because of its very narrow radiation absorption/emission spectra (some of which overlaps with water vapour) and the very small concentration (about 380ppm or 1.3-2.0% of water vapour) has an insignificant contribution to climate.
Kevin Kilty (21:01:47) :
“Convection is a heat engine. Without greenhouse gases, though, it would have only a hot reservoir (the surface). Greenhouse gases provide the cold reservoir for this heat engine and without a cold reservoir in which to expel waste any heat engine will stop running its cycle (to do otherwise would violate the second law).”
I disagree. There are two processes going on. There is a heat engine operating between any hot and cold parts of the surface. Tom Vonk mentioned the day and noght sides, but there are also just albedo differences on the lit surface. The temperature differentials may be not large, but there is a huge solar flux, which even with inefficient conversion still causes vigorous motion.
The second is the adiabatic transfer, leading to the -9.8 K/km lapse rate. This is a reverse Carnot cycle, driven by the forced motion, and transfering heat downward, until the temperature grad reaches the lapse rate. This absorbs kinetic energy (from the above heat engine), but not much, since the energy just works to overcome the leakage due to thermal conduction, which is small.
The nett result is quite different to what Roy Spencer says. Without GHG, there would still be atmospheric motion, and a lapse rate of -9.8 K/km.
I’m travelling at the moment, but when I get back in a couple of days, I’ll post a more detailed explanation on my web site..
Cement a friend (16:26:46) :
I think cba is close to the facts.
There seems to be an opinion that CO2 will absorb all the emitted IR from the surface.
I’ve never seem that before, it’s clearly nonsense.
That is not correct if one looks at the spectra of each of the gases. Water vapour has a much wider spectra than CO2.
Yes but much sparser lines, see here (1% H2O vs 385ppm CO2): http://i302.photobucket.com/albums/nn107/Sprintstar400/H2OCO2.gif
On the NASA website I found a statement that water vapour will absorb eight times the IR wavelengths of CO2. By sight of the spectra that appears correct.
Running it on Modtran it looks more like a factor of two to me.
On earth the driver of climate is water and water vapor. CO2 makes little or no contribution.
Not true.
RE: cba (15:14:41) and All
I may have misunderstood but seeing as you use the Bohr theory of the atom you seem to be under the impression that electronic absorption and emission (i.e. an electromagnetic wave exciting an electron to a higher energy band) is relevant in any significant way to greenhouse gases. Greenhouse gases at atmospheric temperature ranges are concerned primarily with the exchange of thermal radiation within the IR region.
The wavelength at which peak emissivity lies varies with temperature. At the temperature of the sun its peak emissivity lies in the visible/UV region. At the temperature of the atmosphere its peak emissivity lies in the IR region, more specifically between the wavelengths of 4 and 40microns. The dominant mechanism of absorption and emission at these wavelengths for gas molecules in the atmosphere is vibrational, for IR wavelengths below 10microns and rotational, for IR wavelengths above 10microns. Electronic absorption and emission as would be described by the Bohr model only comes into play significantly for UV and visible light for any molecule in the atmosphere. Hence the only time we should be concerned about electronic absorption is when it is concerned with SW radiation from the sun.
On that subject all gas molecules will thermally radiate (i.e. emit radiation of wavelength between 0.1 and 100microns) until they reach their ground or unexcited state (being when they are at 0K). At any temperature above 0K a molecule is excited either electronically, rotationally or vibrationally or a mixture of those and this will cause it to radiate.
Now, the emissivity of greenhouse gases is much higher in the IR spectrum than non greenhouse gases such as N2 and O2. This is due mainly to greenhouse gases such as H2O and CO2 having permanent dipole moments which means when they rotate and vibrate they emit far more IR radiation. Now given that at the temperature of the atmosphere thermal radiation occurs predominantly in the IR region then that is what makes greenhouse gases such as H2O and CO2 such dominant absorbers and emitters of radiation.
And finally a concluding remark on thought experiments. Thought experiments are generally hypothetical concepts that cannot be verified experimentally and therefore fall within the realm of tautology rather than science. Science can still benefit from tautology however and has done in the past. Thought experiments are supposed to stimulate thought and debate to help us explore our own understanding and also perhaps formulate empirical experiments with which our scientific knowledge may be tested. The main concept from this thought experiment is that the greenhouse effect tries to cause a very large perturbation in the earths temperature distribution which would not be there in their absence and that certain (maybe not all) weather processes exist as a consequence to work against this perturbation. This would preclude positive feedbacks. Such conclusions from this thought experiment is exactly what Dr Spencer is testing empirically with his wider work on atmospheric feedbacks.
George E. Smith (13:19:15) :
I’m intrigued by Alex’s information; is that due to some extreme symmetry of electric charge distribution in N2 Alex, or what is the Physics behind its low emission.
Obviously gases do radiate as evidenced by the sun; but I have a hard time believing that the main radiation from the atmosphere (earth) is due to emission from GHGs rather than from the bulk of the atmopshere.
Others have suggested that during molecular collisions, the conditions might be such as to admit radiative transitions that might normally be forbidden for isolated molecules (of ordinary atmospheric gases).
If Alex can steer us toward any lterature, it would be helpful.
George, any freshman Physical Chemistry text should give you the basics about the homonuclear diatomics, for more detail try ‘Molecular Spectra and Molecular Structure’ by G Herzberg it’s what I used as an undergraduate but I believe there’s been a new printing (it should be cheap).
RE: Oliver Ramsay (20:38:52)
“If somebody has the patience to explain the mechanics of cold gas emission in layman’s terms, I’ll be grateful!”
There seems to be a lot of debate going on here about the emissivity of N2 and O2 and it is understandable why. I have dug out two textbooks on the subject which I will quote directly to illustrate a point. The first is from a general fundamental thermodynamics textbook:
‘All bodies at a temperature above absolute zero emit thermal radiation’
The second is from a textbook dealing with the more specific fundamentals of atmospheric radiation:
‘Although nitrogen and oxygen molecules can rotate, in so doing they do not radiate (much)’
Both quotes are technically correct but the second quote is only technically correct because of the word added at the end in parenthesis. Where it not for the added ‘(much)’ then the second sentence would only be practically correct. Most text books a guess would just not bother with the ‘(much)’ and settle for being practically correct. Yes O2 and N2 radiate in the IR region but as far as our atmosphere is concerned I wouldn’t worry about it.
The second point of confusion is in WHY molecules radiate. Individual atoms can only absorb and emit radiation by electron promotion. Some people seem to have extended this to think that molecules can only absorb and emit radiation by electron promotion but this is incorrect. In fact if the IR region it is excitation and relaxation of internal vibration and rotation states of a molecule that are responsible for the majority of the radiation emitted and absorbed. This is due to the change in acceleration (either rotational or vibrational) of charge particles. Molecules with a permanent dipole such as CO2 and H2O therefore emit far more radiation in the IR region than those molecules which would have to wait for random chaotic fluctuations to cause a temporary dipole.
I hope that sheds some light on the issue.
Alberto (12:20:30) :
The emission of gases in the atmosphere, is spontaneous emission (all directions) or induced emission (in the same direction as the inductor photon)? I think it is mostly induced.
There is total confusion between atomic theory which is beautifully described by quantum mechanics, quantum theory of large numbers, i.e. quantum statistical mechanics, and thermodynamics, which connects through simple statistical mechanics with quantum statistical mechanics.
If people discussing here have had physics courses I am amazed.
Forget quanta.
Classical thermodynamics of the 19th century showed that all matter, which then was separate into solids, fluids and gases, radiates according to the flux=constant*T^4 law. No quanta in the derivations ( first part of my thermodynamics book,Sears,edition 1953, undergraduate thermodynamics).
Then, at the end of the 19th century, people started thinking: the frequency distribution of the radiation, Wien law, was not exactly right, and Planck’s radiation curve emerged and the whole story of quanta etc. etc.
Sure, an isolated molecule will not radiate if it is not in the ground state.
Sure, it might be induced to radiate if it is in a higher state and a proper quantum passes within range, lazers work.
BUT the atmospheric gases are statistical ensembles of incoherent, i.e. phase unknown and unknowable, origin. There is no way induced radiation at the microscopic level will get coherent in bulk in the atmosphere.
Now about the question of temperature. Temperature comes from the kinetic energy of molecules. The inetic energy of molecules changes through collisions, even if no atom is in a higher state and can radiate and change its kinetic energy.
What do collisions mean at the atomic level? That the wanderwaals forces http://en.wikipedia.org/wiki/Van_der_Waals_force , come within range, and very soft continuum photons are exchanged, some of them leaving through space, and diminishing the kinetic energy of the individual atom/molecule. This in the statistical mechanics language means cooling the bulk. i.e.kinetic energy into photon/EM energy.
Surprise maybe for many here, infrared is a continuum, photons can exist in the whole spectrum etc. etc.
RE: Oliver Ramsay (20:38:52)
Sorry Oliver but I should correct my previous post. In the last paragraph I said ‘change in acceleration’. This should be ‘change in velocity’ or just plain acceleration.
Correction:
“Sure, an isolated molecule will not radiate if it is not in the ground state.”
Sure, an isolated molecule will not radiate if it IS in the ground state.
CBA :
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I agree . Basically we are saying the same thing . In LTE absorption of frequency f = emission of frequency f .
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AnnaV
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Yes you are right , there is sometimes too much mixing between QM and standard 19th century statistical thermodynamics . It is a necessary feature of a successful blog dealing with science . I believe that it is the duty of physicists that post here to help to educate the interested people . Time spent in education is the best spent time .
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Alex Harwey
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You misunderstood . Probably because you have no knowledge of QM . Unfortunately radiation is precisely a domain where QM rules and without at least a basic grasp of it , you can’t hope to understand .
So I’ll try to go to more details .
It is the same thing as what cba wrote but explained from the QM point of view .
A molecule has its energy levels quantified . I say levels because there are several modes – electronic , vibrationnal , rotationnal .
If we have a large collection of molecules , they will not be all at the same energy level .
There will be a distribution of the molecules among the energy levels (e.g a percentage X% of the total is at energy E0 , a percentage Y% is at energy E1 etc) .
IN LTE this ditribution is given by the Maxwell Boltzmann law .
This law depends only on the energy and temperature .
In other words the number of molecules in the state E1 (first excited state) in a TINY volume in LTE (like cba wrote) is a constant.
Now if there is IR radiation with frequency equal to E1-E0 (f.ex the 15µ for a CO2 molecule) , some molecules will absorb it and go from E0 to E1 .
Doing that , they will INCREASE the %tage of molecules in the state E1 .
But as the LTE condition is dictating that this %tage must be constant , there is NECESSARILY exactly the same number of molecules in this tiny volume that will go the other way from E1 to E0 and emit a photon .
That’s why in LTE we have necessarily :
absorption of frequency f = emission of frequency f .
The troposphere is in LTE . QED .
.
As for the huge temperature differential and in addition to what Nick Stokes already commented .
The night half will try to go to a radiative equilibrium which is at 3 K .
The day half will receive all Sun energy and will also try to go to a radiative equilibrium which is above 370K at equator .
This creates a HUGE temperature differential between the day and the night halves . The result are storms of astronomical power which try to evacuate energy from the day half to the night half .
If the planet rotates , the differential will be lower but the flow will be much more complex (giant hurricane like structures) .
Re: George E. Smith (13:19:15) :
I haven’t got a lot of time just now. Please refer to the HITRAN data, it is not freely available at the HITRAN site. But it is here:
http://vpl.astro.washington.edu/spectra/allmoleculeslist.htm
Compare the area/molecule for N2 and CO2 (The scales vary from 10^-30 to 10^-18 so make sure you check the scale for each section of the spectra.
More later, hopefulely.
Alex
RE: Nick Stokes (20:57:57): replying to Kevin Kilty (21:01:47)
I think it is hard to call the convection system in our atmosphere anything but a heat engine. We are fortunate to have water vapor in our atmosphere to yield its latent heat of vaporization on condensation to accelerate the process. If the upper atmosphere could not radiate convected heat energy away (a big if in real world situations — this is a thought experiment discussion) then convection would be shut down by the formation of a temperature inversion that should cause the tropopause to be at or near the surface.
I believe the basic point being made here is that convection cannot continue unless the convected heat can be radiated out from the upper atmosphere. Greenhouse trace gases could provide that outlet as they radiate as well as absorb in the ETR (Earth Thermal Radiation, 6 to 20 micron) band. I think clouds and dust in the upper atmosphere might be even more significant in broadcasting ETR energy out from the upper atmosphere.
—–
I note it has been reported that the altitude of the tropopause has increased several hundred feet in the past two decades and researchers including Benjamin Santer of the Lawrence Livermore National Laboratory have identified anthropogenic greenhouse emissions as the primary cause. This suggests to me that the convection engine may be becoming slightly more active to compensate for the minor reduction in the available thermal transmission bandwidth.
“”
Alex
.. may have misunderstood but seeing as you use the Bohr theory of the atom you seem to be under the impression that electronic absorption and emission (i.e. an electromagnetic wave exciting an electron to a higher energy band) is relevant in any significant way to greenhouse gases. Greenhouse gases at atmospheric temperature ranges are concerned primarily with the exchange of thermal radiation within the IR region.
“”
Actually no, the purpose of the bohr example is to explain the concept that for an atom rather than a complex molecule that longer emission wavelengths are not possible without first exciting the atom to higher states. All emissions to the ground state are the Lyman series in the uV, the visible Balmer series is related to emissions ending at the first excited state and they are all still in the visible. However, with enough excitation, like heat, one can achieve a BB spectrum, like the Sun’s photosphere at 6000k but one is not going to see any emissions from hydrogen in the Earth’s atmosphere due to anything related with thermal absorption and emission. One can then infer the highly limited nature of very simple molecules which do not have tremendous numbers of vibrational and rotational states like the more complex co2, h2o, ch4 molecules.
In other words, it’s about what is NOT happening in the atmosphere.
“”
alexb
On that subject all gas molecules will thermally radiate (i.e. emit radiation of wavelength between 0.1 and 100microns) until they reach their ground or unexcited state (being when they are at 0K). At any temperature above 0K a molecule is excited either electronically, rotationally or vibrationally or a mixture of those and this will cause it to radiate.
“”
While I would have thought that rotational is more past 100 um and that vibrational is dominant from 1 to 100 um at Earth’s temperatures, I can’t agree on this area. You have to have internal states of excitment in order to radiate and for a gas, that is a spectrum of discrete states. Temperature is heat or external motion. If there are no excited states low enough to accept energy into one of these discrete states, then it must remain thermal and cannot ‘cock’ the molecule (like a gun hammer to detente) and ultimately generate a photon. Absolute 0 is when these molecules stop moving around at all. If there is not enough thermal energy to raise the molecule to the lowest excited state capable of emission, then you don’t have the ability to have emission even though you have above zero temperature.
At least in the bohr case, you have the potentially counter intuitive result that the ‘lowest’ energy states only emit in the uV while a transition between higher energy states can emit in the visibile and IR but for this to happen, it has to be excited to above the 1st excited state.
As for the rest of your post not specifically commented on here, I think we are in full agreement.
“”
Alex
‘All bodies at a temperature above absolute zero emit thermal radiation’
The second is from a textbook dealing with the more specific fundamentals of atmospheric radiation:
‘Although nitrogen and oxygen molecules can rotate, in so doing they do not radiate (much)’
“”
First internal quote – key word is body – a solid or liquid. They’re not talking gas.
Second internal quote, sounds reasonable.
I’ve seen line graphs even in the visible for o2 and / or n2 showing these. They are individual lines that are not full absorption for the Earth’s atmosphere even for the entire thickness at their peak. Comparing with co2 that has between 20,000 and 50,000 lines bunched together in bands of full absorption over very short distances hardly makes for much of a comparison.
I can see a beginning text ignoring the N2 O2 radiation in order to not confuse the student. That’s done all the time, with entire courses. One learns Newton’s theory of gravity first, not Einstein’s general relativity. I think nowadays though that it tends to be mentioned that Newton’s theory has been replaced even while introducing it.
Note that the mentioned visible is absorption only as the thermal energy is insufficient to raise the molecule to emission in the visible within the Earth’s atmosphere. The energy absorbed in that area is totally thermalized then radiated in the IR where the temperature is sufficient to excite the ghg molecules.
AnnaV
while the van der Waals forces do provide more opportunity, I think they are mostly dominant in liquid (fluid) where you have a BB continuum. For our atmosphere, it is well described by the ideal gas law which provides good results, despite the vdW ability to provide more accurate results. For better results, one might use the vdW to describe a gas, especially if it is pressurized.
There is an intermediate as well, called dimers. This where you can have water vapor continuum based upon groups of h2o molecules as well. Dimers may be somewhat related to vdW forces and may be a form of vdW molecules.
I think though the vdW effects are mostly towards the very long wavelengths and low energy, far out on the tail of the BB distribution. Whether they are significant w.r.t. conduction in air, I’m not sure. If so, then they would be important for Dr. Roy’s thought experiment. I don’t think they are of significance in the real atmosphere.
btw, my Sear’s thermo book is also the 1953 second edition, but it is the 5th printing (1964). I liked it much better than Reif which is used sometimes as an undergraduate book and sometimes as a graduate level book.
AlexB,
Thank you for that.
I find it easier to visualize vibrational emission than rotational. Rotational seems similar to translational but I don’t see how changes in molecular velocity occur without interaction with other particles. Does N2 radiate so little rotationally because there are not opposite charges constantly changing places?
TomVonk (02:05:57) :
But as the LTE condition is dictating that this %tage must be constant , there is NECESSARILY exactly the same number of molecules in this tiny volume that will go the other way from E1 to E0 and emit a photon .
That’s why in LTE we have necessarily :
absorption of frequency f = emission of frequency f .
The troposphere is in LTE . QED .
No, the highlighted part is not correct, it is only necessary in LTE that the transition is made, not that emission occurs, in fact in the troposphere that is effected mostly by collisions not emission. It is the emissivity that equals absorptivity not “absorption=emission” (Kirchoff’s law).
Pseudoscience at its best. For a real eye opener read Dr. Spencer’s “In
Defense of the Greenhouse effect” that he references. He Say’s,
” I’ll admit I used to question it, too. So, many years ago Danny Braswell and I built our own radiative transfer model to demonstrate for ourselves that the underlying physics were sound.” So the model apparently confirms reality.
But the physics is solid because all values and assumptions put into black
body theory math is unquestioned and inviolable. Is it? A black body in
reality is an idealized, fictional body that absorbs ALL electromagnetic radiation that falls on it and at ALL wavelengths. Well unfortuneately there is no material known that exhibits these properties so a black body is an
abstraction. No true black body can be made real. Black body theory is
also tied into quantum mechanics but quantum mechanics as far as I can
tell is a failure. When was the last time you bought a new toothbrush based
on Qm? The earth is not a black body or a grey body for that matter! The
earth is continuously and unevenly heated due to cloud cover. Yes that one
great sore point for modelers, clouds. No matter how many terrabytes you
have you will never be able to come up with a an accurate algorithm to
predict them. Uneven heating and uneven emission along with clouds
causes chaos in the weather system. Chaos by definition defies modelling. There is much to criticize and little space to do it but in short:
1. Mr. Spencer agrees that the term “greenhouse effect” is a misnomer.
So he actually agrees that there is really no greenhouse effect
taking place as in a real greenhouse but then says it has stuck so
“get used to it.” And of course his articles are full of the term.
Dr. Spencer ever heard of Mean What You Say And Say What You Mean?
Incorrect wording leads to confusion. This is why many people
believe heat is trapped in the atmosphere.
2. His implication that heat can cool is sheer nonsense. Since when
does a hot object cool something? The jar experiment he uses
invalidates this. Just as nonscientific is the notion that layers of
the atmosphere radiate heat downward. To do this the atmosphere
must be considered as a source of heat. It is not. Black is not
white. Net flow of heat is all that counts in the real world not the
insensible heat referred to by Dr. Spencer. By the way if the
atmosphere did prove to be a source of heat then overunity or
free energy would be here already. It isn’t. Here’s the capper:
“The Earth’s surface cools by losing heat which then chills the
air in contact with it (nighttime). Hey, Mr. Spencer what planet
do you live on? (lol)
3. The earth is open to space and heat is constantly released. This
does not qualify the earth and it’s atmosphere as a feedback
period. Talk about positive and negative feedbacks are fantasy
talk. There are NO experiments that have been done IN the
atmosphere to confirm this. ERBE and CERES are only precursors
to the work that should be done (stratosphere, mesosphere).
Measuring only from the ground and space do not make direct
measurements. What is going on is inferred from the data using
algorithms. Water vapor complicates things a great deal.
4. “The Greenhouse Effect Works For Now”, but as Dr. Spencer so
\ aptly points out, the Greenhouse part is a misnomer and incorrect.
So what kind of effect is it then? The retention effect?
His claim that the theory is supprted by lab experiments is
false. No lab can replicate the open wild.
Now the best for the last – He claims the models give a “vertical
temperature profile that looks very much like what we observe
in nature. Really, then where is the hotspot shown in all the
models. It has never been observed or recorded so poor Santer
had to go looking for it in the noise(desperation).
I can only conclude that Dr. Spencer is not only in serious denial
but has succumbed to the next stage, delusion.
Agw physics is an abstracted idea sprinkled with bits of reality
so as to convince the masses.
For The Misled
Bdub
Brian (09:05:08)
” His implication that heat can cool is sheer nonsense. Since when
does a hot object cool something”
If an object is radiates heat, it is losing energy and falling in temperature. Take a heated poker out of a furnace and expose it to normal room temperature. What was receiving heat is now radiating relative to its new environment until it thermalises to room temperature. Basic 2nd law of thermodynamics
“The Earth’s surface cools by losing heat which then chills the
air in contact with it (nighttime). Hey, Mr. Spencer what planet
do you live on? (lol)”
Well thats fairly basic. if the surface is lets say 10C, then it doesn’t radiate 10C worth of energy, as equilibrium takes place – if warming takes place at the equator then heat escapes at the poles This heat is carried by convection, not radiation and generally travels around or through greenhouse gases – the consequence is that water vapour cools by evaporation instead of retaining heat and co2 doesn’t do much anyway, which is why the temperature falls with altitude. Even if the earth were superheated, it would return to equilibrium soon as it cools more dramatically. Convection is afairly slow process, although heat tends to stay as long as it can where it is (in the atmosphere where its kept by a mix of air pressure, gravity and other such forces). Heat is not a constant. It is a form of energy that can disippate (2nd law). If you catch wind travelling 20mph across LA at a temperature of 20C, the urban area will increase that temperature to say 23C, thn on leaving the urban area, reduce back to 20C. What happende to that heat? It didn’t maintain itself as a constant, but cooled on leaving the urban zone.
There is a myth in climatology that heat has all the properties of a solid. Like when you infer resistance and force when pulling alever, that resistance disippates as son as you let go: Energy isn’t a permanent or solid characteristic.
the aforegoing is another way of saying that if there were no inaptly named greenhouse gases, then the temperatures we know would still be about the same as they don’t change the energy in the atmosphere.
OK, lets talk quantum mechanics.
What is a molecule?
A molecule is composed of two or three or more atoms and they stay together because energetically it is advantageous to share the electrons then to be apart. Each atom will have its energy levels modified because of the communal share of electrons and many new energy levels will appear because of the extra degrees of freedom available for the electrons to organize themselves: rotational and vibrational depending on the topology of how the atoms are mainly distributed in space. These are the energy levels that absorb and radiate infrared and softer and are distinct for the molecule rather than the atom.
Let us then have two molecules colliding. What does it mean? It means that they graze close enough so that their electron clouds can interact. Things that can happen are:
a)the collision is elastic, so only direction changes
b)the collision is hard enough that one of the atoms gets an electron in a higher state. This will radiate back and the molecules will lose energy
c)a rotational energy level, or a vibrational energy level absorbs part of the kinetic energy and eventually radiates back to the ground state, maybe in cascade. One or both molecules loose kinetic energy in this way, and the photon(s) leaving has(ve) distinctive energy
d)the electron clouds interact and one of the virtual photons of the interaction becomes real and leaves taking kinetic energy, without changing the quantum state of the molecules. One or both lose kinetic energy and the photon leaving is in the continuum.
In a gas we have ten-to-the- twentieth- plus molecules and we need statistical tools and finally thermodynamic quantities to describe the collective behavior. All of these interactions are taking place all the time and the energy loss from departing photons is what builds up to the F=constant*T^4 behavior, where the kinetic energy is hidden in the temperature connection.
All matter will radiate this way at the specific temperature.
Now we come to the matter of transparency. Some molecules are more transparent to through going radiations than other molecules due to the specific spectrum described in c) above. Thus given infrared radiation from the ground the process of capture and decay will introduce a delay on the way to outer space by turning photon energy into kinetic molecular and potential and statistically appearing as an increase in temperature, or a delay in cooling. That is what is misnamed “the greenhouse effect” and the responsible molecules are mainly H2O and a bit of CO2.
So I cannot understand the statement in the post above:
So, how is this different from what happens in the real world? Well, notice that what we are left with in this thought experiment is an atmosphere that is heated from below by the ground absorbing sunlight, but the atmosphere has no way of cooling…except in a very shallow layer right next to the ground where it can cool by conduction at night.
If there were no GH gasses the atmosphere would cool even better because it would be transparent to the infrared coming from the ground, and it would radiate with T^4. What happens every night in the dry deserts.
anna v (13:21:20) :
Don’t know if you are commenting back to me. I totally agree with each of your statements here. You bring in ‘all’ of the other factors happening zillions of times every second. I was careful to only address one particular aspect of this complex system. Heat in the water or ground radiated upward (angle above horizontally). That radiation must end up radiating to space in the long run (many seconds, hours or days) after bouncing for a while splitting its momentum in a zillion parts but the sum of the original parts always adding to that upward angle and velocity it started with (momentum).
Now you have to look at all of the other processes and interactions, one by one, defined in their own ‘isolated specially defined’ case to somehow understand this very complex system. System level, ruled by quantum mechanics and in isolated special cases thermodynamics.
Just wanted good minds out there to also think at this core level. Enjoyed the conversion, maybe more in the future on some other aspects.
Here’s a quick calculation on the situation of no ghgs (and no h2o vapor)
Incoming average power at TOA is 341.
Earth albedo is 0.31 = 0.22 (clouds and atm) + 0.08 (average surface)
Energy arriving at surface = 341 – reflected = 341 (1-0.08) = 314 w/m^2
for balance, outgoing must be equal and since there’s no clouds or ghgs to block outgoing, the average outgoing power then is 314 w/m^2
doing a reverse calculation from stefan’s law, T = 273K, roughly freezing as compared to today’s temperature of 288.2K which is 15 K lower than present.
This is different than the vaunted 33k contribution for ghgs because of the difference in albedo. If one holds the albedo constant at 0.31, then the balancing radiation is 235w/m^2 and that corresponds to 254 K which is the 34 deg C below our current temperature level. This assumes liquid water oceans, vegetation, etc. with no ghgs but assumes cloud albedo only. Clouds will block outgoing LWR and raise the necessary temperature somewhat. For Earth to become like Mars or the Moon, the loss of liquid or solid water and vegetation would tend to average out the albedo to around 0.15 – give or take a bit. A snowball Earth would raise the albedo for most of the Earth to get the albedo more towards 0.5 and an even lower temperature.
Whichever scenario one wants to consider, I think you’ll find that the atmospheric temperature will no longer have a lapse rate or definitely not the current lapse rate and that conduction / convection will basically maintain that for whatever emissions are happening. While there may still be a lapse rate, it won’t be the one we are familiar with. without the secondary effects that become important only after the primary has been ‘thought away’ the lapse rate would tend to zero.
While simplfied scenarios such as Dr. Roy’s can be quite instructive on the basic concepts, it’s best not to look too closely at them because secondary effects in the real world will start to become important and the power of simplicity becomes lost in additional details that become more important than they would be in the original atmosphere.
cba (14:32:20) :
I follow you. It’s the same problem I have sometimes when reading comments on isolating examples as the one Dr. Spencer used. I try to follow some rules:
– You must never bring aspects into thought examples that were never meant to exist in the example in the first place. Follow exactly but be lenient.
– Assume the person knows what he/she is talking about. If you think he/she meant a different word which makes it correct in your mind, change it, don’t pick on words unless there is no way you can make the speaker correct. Then state it as a question of contention. He might (and probably does) know what he speaking of. Or, state your alternate word so others can use it and maybe make it clear to them.
– You can go from single particle aspects to higher level aspects (as: thermodynamics) if viewed with unlimited precision as mother nature does but you can never go backwards from equations of macro system and then talk of a particles, especially speaking of vectors in momentum’s case. The macro systems are conglomerates and usually vector aspects in equations don’t exist at all.
– Don’t speak of up radiation or down radiation, flipping them around without making sure energies (kinetic & potential) and momentum are correctly take into account and are always preserved. Such as talking temperature without also accounting for pressure and volume changes globally.
Just my view on the subject. Helps to keeps physics conversations sane and clear for me.
Re:P. Nelson (12:05:29)
Unfortunately you do not understand the argument. Your hot poker example
misses the point completely. The debate is about the heat of one object
in relation to ANOTHER object. What exactly are you trying to convince
me of? Also what did you you think I was talking about when I mentioned
net heat flow. Your second post is nearly incomprehensible. Heat escaping
at the poles has nothing to do with the statement.
Here’s the point:Take a hot summer day, after a couple of hours after dark
go put your hand on the driveway tarmac (it’s dry , no water) then put your
other hand in the air. Does it feel as warm? I have done this countless
times and even without a thermometer it’s easy to tell that the air is
cooler than the ground. Go back out at midnight. The surface is cooler
and theres no water to evaporate. Where did the heat go. How about
straight up towards space. This is confirmed during the day while
sitting watching the heat waves rising up from the ground. Do they
move sideways, move up on an angle or dance the jig? No they don’t!
Heat from the earth’s surface moves straight up causing convection.
Why? Because if you want to talk cold, is space not at -273 degrees
centigrade? There are no real physical barriers in the atmosphere to
simple thermal heat escaping. Fourier’s belief that the atmosphere acts
as the glass of a greenhouse is simply that, a belief. He did NO
atmospheric experiments to prove it. The layers in the atmosphere
are nature’s most efficient way of organizing heat transfer to space.
Blankets indeed! Oh, CO2 with a concentration of .0387 percent
by volume is NOT a viable thermostatic control for the planet. At
this concentration CO2 molecules would have to have nuclear fission
capabilities. Climate and weather have nothing to do with C02. The
greenhouse effect is just leftover propaganda that Dr. Roy apparently
needs to defend and legitimize, but really in relation to the earth its
just a confused load of poppycock. OH and Anna V., I still want my
Qm based toothbrush!
Bdub