Guest Post by Willis Eschenbach
I’ve been reflecting over the last few days about how the climate system of the earth functions as a giant natural heat engine. A “heat engine”, whether natural or man-made, is a mechanism that converts heat into mechanical energy of some kind. In the case of the climate system, the heat of the sun is converted into the mechanical energy of the ocean and the atmosphere. The seawater and atmosphere are what are called the “working fluids” of the heat engine. The movement of the air and the seawater transports an almost unimaginably large amount of heat from the tropics to the poles. Now, none of the above are new ideas, or are original with me. I simply got to wondering about what the CERES data could show regarding the poleward transport of that energy by the climate heat engine. Figure 1 gives that result:
Figure 1. Exports of energy from the tropics, in W/m2, averaged over the exporting area. The figures show the net of the energy entering and leaving the TOA above each 1°x1° gridcell. It is calculated from the CERES data as solar minus upwelling radiation (longwave + shortwave). Of course, if more energy is constantly entering a TOA gridcell than is leaving it, that energy must be being exported horizontally. The average amount exported from between the two light blue bands is 44 W/m2 (amount exported / exporting area).
We can see some interesting aspects of the climate heat engine in this graph.
First, like all heat engines, the climate heat engine doesn’t work off of a temperature. It works off of a temperature difference. A heat engine needs both a hot end and a cold end. After the working fluid is heated at the hot end, and the engine has extracted work from incoming energy, the remaining heat must be rejected from the working fluid. To do this, the working fluid must be moved to some location where the temperature is lower than at the hot end of the engine.
As a result, there is a constant flow of energy across the blue line. In part this is because at the poles, so little energy is coming from the sun. Over Antarctica and the Arctic ocean, the sun is only providing about a quarter of the radiated longwave energy, only about 40 W/m2, with the remainder being energy exported from the tropics. The energy is transported by the two working fluids, seawater and air. In total, the CERES data shows that there is a constant energy flux across those blue lines of about six petawatts (6e+15 watts) flowing northwards, and six petawatts flowing southwards for a total of twelve petawatts. And how much energy is twelve petawatts when it’s at home?
Well … at present all of humanity consumes about fifteen terawatts (15e+12) on a global average basis. This means that the amount of energy constantly flowing from the equator to the poles is about eight-hundred times the total energy utilized by humans … as I said, it’s an almost unimaginable amount of energy. Not only that, but that 12 petawatts is only 10% of the 120 petawatts of solar energy that is constantly being absorbed by the climate system.
Next, over the land, the area which is importing energy is much closer to the equator than over the sea. I assume this is because of the huge heat capacity of the ocean, and its consequent ability to transport the heat further polewards.
Next, overall the ocean is receiving more energy than it radiates, so it is exporting energy … and the land is radiating more than it receives, so it is getting energy from the ocean. In part, this is because of the difference in solar heating. Figure 2, which looks much like Figure 1, shows the net amount of solar radiation absorbed by the climate system. I do love investigating this stuff, there’s so much to learn. For example, I was unaware that the land, on average, receives about 40 W/m2 less energy from the sun than does the ocean, as is shown in Figure 2.
(Daedalus, of course, would not let this opportunity pass without pointing out that this means we could easily control the planet’s temperature by the simple expedient of increasing the amount of land. For each square metre of land added, we get 40 W/m2 less absorbed energy over that square metre, which is about ten doublings of CO2. And the amount would be perhaps double that in tropical waters. So Daedalus calculates that if we make land by filling in shallow tropical oceans equal to say a mere 5% of the planet, it would avoid an amount of downwelling radiation equal to a doubling of CO2. The best part of Daedalus’s plan is his slogan, “We have to pave the planet to save the planet” … but I digress).
Figure 2. Net solar energy entering the climate system, in watts per square metre (W/m2). Annual averages.
You can see the wide range in the amount of sunlight hitting the earth, from a low of 48 W/m2 at the poles to a high of 365 W/m2 in parts of the tropics.
Now, I bring up these two Figures to highlight the concept of the climate system as a huge natural heat engine. As with all heat engines, energy enters at the hot end, in this case the tropics. It is converted into mechanical motion of seawater and air, which transports the excess heat to the poles where it is radiated to space.
Now, the way that we control the output of a heat engine is by using something called a “throttle”. A throttle controls the amount of energy entering a heat engine. A throttle is what is controlled by the gas pedal in a car. As the name suggests, a throttle restricts the energy entering the system. As a result, the throttle controls the operating parameters (temperature, work produced, etc.) of the heat engine.
So the question naturally arises … in the climate heat engine, what functions as the throttle? The answer, of course, is the clouds. They restrict the amount of energy entering the system. And where is the most advantageous place to throttle the heat engine shown in Figure 2? Well, you have to do it at the hot end where the energy enters the system. And you’d want to do it near the equator, where you can choke off the most energy.
In practice, a large amount of this throttling occurs at the Inter-Tropical Convergence Zone (ITCZ). As the name suggests, this is where the two separately circulating hemispheric air masses interact. On average this is north of the equator in the Pacific and Atlantic, and south of the equator in the Indian Ocean. The ITCZ is revealed most clearly by Figure 3, which shows how much sunlight the planet is reflecting.
Figure 3. Total reflected solar radiation. Areas of low reflection are shown in red, because the low reflection leads to increased solar heating. The average ITCZ can be seen as the yellow/green areas just above the Equator in the Atlantic and Pacific, and just below the Equator in the Indian Ocean.
In Figure 3, we can see how the ITCZ clouds are throttling the incoming solar energy. Were it not for the clouds, the tropical oceans in that area would reflect less than 80 W/m2 (as we see in the red areas outlined above and below the ITCZ) and the oceans would be much warmer. By throttling the incoming sunshine, areas near the Equator end up much cooler than they would be otherwise.
Now … all of the above has been done with averages. But the clouds don’t form based on average conditions. They form based only and solely on current conditions. And the nature of the tropical clouds is that generally, the clouds don’t form in the mornings, when the sea surface is cool from its nocturnal overturning.
Instead, the clouds form after the ocean has warmed up to some critical temperature. Once it passes that point, and generally over a period of less than an hour, a fully-developed cumulus cloud layer emerges. The emergence is threshold based. The important thing to note about this process is that the critical threshold at which the clouds form is based on temperature and the physics of air, wind and water. The threshold is not based on CO2. It is not a function of instantaneous forcing. The threshold is based on temperature and pressure and the physics of the immediate situation.
This means that the tropical clouds emerge earlier when the morning is warmer than usual. And when the morning is cooler, the cumulus emerge later or not at all. So if on average there is a bit more forcing, from solar cycles or changes in CO2 or excess water vapor in the air, the clouds form earlier, and the excess forcing is neatly counteracted.
Now, if my hypothesis is correct, then we should be able to find evidence for this dependence of the tropical clouds on the temperature. If the situation is in fact as I’ve stated above, where the tropical clouds act as a throttle because they increase when the temperatures go up, then evidence would be found in the correlation of surface temperature with albedo. Figure 4 shows that relationship.
Figure 4. Correlation of surface temperature and albedo, calculated on a 1°x1° gridcell basis. Blue and green areas are where albedo and temperature are negatively correlated. Red and orange show positive correlation, where increasing albedo is associated with increasing temperature.
Over the extratropical land, because of the association of ice and snow (high albedo) and low temperatures, the correlation between temperature and albedo is negative. However, remember that little of the suns energy is going there.
In the tropics where the majority of energy enters the system, on the other hand, warmer surface temperatures lead to more clouds, so the correlation is positive, and strongly positive in some areas.
Now, consider what happens when increasing clouds cause a reduction in temperature, and increasing temperatures cause an increase in clouds. At some point, the two lines will cross, and the temperature will oscillate around that set point. When the surface is cooler than that temperature, clouds will form later, and there will be less clouds, sun will pour in uninterrupted, and the surface will warm up.
And when the surface is warmer than that temperature, clouds will form earlier, there will be more clouds, and higher albedo, and more reflection, and the surface will cool down.
Net result? A very effective thermostat. This thermostat works in conjunction with other longer-term thermostatic phenomena to maintain the amazing thermal stability of the planet. People agonize about a change of six-tenths of a degree last century … but consider the following:
• The climate system is only running at about 70% throttle.
• The average temperature of the system is ~ 286K.
• The throttle of the climate system is controlled by nothing more solid than clouds, which are changing constantly.
• The global average surface temperature is maintained at a level significantly warmer than what would be predicted for a planet without an atmosphere containing water vapor, CO2, and other greenhouse gases.
Despite all of that, over the previous century the total variation in temperature was ≈ ± 0.3K. This is a variation of less than a tenth of one percent.
For a system as large, complex, ephemeral, and possibly unstable as the climate, I see this as clear evidence for the existence of a thermostatic system of some sort controlling the temperature. Perhaps the system doesn’t work as I have posited above … but it is clear to me that there must be some kind of system keeping the temperature variations within a tenth of a percent over a century.
Regards to all,
w.
PS—The instability of a modeled climate system without some thermostatic mechanism is well illustrated by the thousands of runs of the ClimatePredictionNet climate model:
Note how many of the runs end up in unrealistically high or low temperatures, due to the lack of any thermostatic control mechanisms.
Willis Eschenbach says:
December 28, 2013 at 10:32 pm
argon will absorb and emit visible light at very high temperatures, as your link shows. However, for earth-like temperatures, they neither absorb nor emit IR.
How many suns were surrounding your planet? Thousands AFAIR. They will heat it to a ‘very high temperature’, no?
Willis 10:32pm: You are up against Max Planck here so be careful. Be very, very careful.
“However, for earth-like temperatures, they neither absorb nor emit IR.”
No. In this earth-like example, Planck’s law shows MOST of the argon atm. emission will be IR. Even at lower temperatures the law shows most of the emission in IR. This is true all the way down to nan0Ks. Every mass spontaneously and continuously emits radiation over the entire spectrum as described by Planck’s Law, you know the one with 3 fundamental constants in it. Cite Bohren 2006 and 1998 (p. 39) texts.
If you want to think about absolute zero, think of entropy. To get rid of all the residual entropy in a system takes an infinite number of process steps. So as far as we know 0.0K (no IR) is not possible but experimentalists have come close at great expense. This is a 2nd Law view of absolute zero.
Hence even adding very cold Ar atm.s will increase the surface Tmean above S-B deep space vacuum. Miniscule amounts above vacuum S-B but non-zero amounts.
Although no gas is strictly ideal, earth gaseous atm. can be taken to be good approx. to ideal. I have not come across a terrestrial atm. phenomenon that is a consequence of the departure of atm. gases from ideality. Would be delighted to learn of such a phenomenon.
Willis:
The one problem with thought experiments is you have to be very very careful about their limitations and definitions. You also have to avoid projecting their results beyond fair comparisons. You have explained a situation that should be impossible as you define the problem, but you have also defined the conditions so that they explicitly violate the conditions that N&Z specified in their theory, and are physically impossible in the real world.
They also carefully specify that the common use of the S-B as applied to planets is flawed and they point out why. Using their calculation method their formula results in almost perfect correspondence with measured conditions on real planets.
They are talking about gray bodies not black bodies, using real measured emissivities of real planets in their calculations.
They explicitly limit the application to planets with “effective atmospheres”. As posted in their original discussions and some of the follow up discussions, the atmosphere must be dense enough to behave as a gas envelope constrained by gravity. Your totally IR transparent atmosphere is functionally identical to a planet with no meaningful atmosphere and is therefore a condition that they specifically exclude.
They also specify that their Nte can be (Nte ≥ 1.0). So a condition of no enhancement ie Nte=1.0 is perfectly legitimate value under their theory, and would be the obvious case for an atmosphere that was specifically defined to not conform to any real world gasses.
All real gasses radiate energy in some part of the electromagnetic spectrum at all pressures and temperatures above absolute zero. As a result any real world atmosphere will set up heat flow from surface to outer space through leakage of energy at some electromagnetic frequency. As a result there will always be a lapse rate in any real atmosphere. Therefore your test conditions are not possible in the real world. Your specified conditions are a violation of the theory that they propose.
It is like setting up a proof that involves dividing by zero. You simply cannot get there from here.
They specifically point out the problems with the “effective radiation surface model” and instead actually in passing support your theory in that they confirm that a large fraction of our planetary albedo is due to clouds and their reflectance, but then go on to say that working from the albedo to get to the effective temperature is flawed and the proper method is to derive the correct surface albedo of the planet and the real temperature of the surface not a monochromatic albedo value for the IR spectrum.
They point out that the Green house theory is demonstrated and calculate based on IR flux (computed against a black body) which is demonstrating its existence by its supposed cause, and propose the proper method is to measure physical mean temperature to calculate the enhancement effect.
Just to be sure in case there is any misconception I am not in any way trying to diminish your thermostat effect theory. In fact I have strongly supported your theory from the very beginning. I have actively advocated the same concept for years as a result of my storm chasing and you have done a very good job of encapsulating what I always thought was bloody obvious once you go out and observe thunderstorms and cloud formations or a regular basis as storm chasers and sailor are inclined to do.
Trick says:
December 28, 2013 at 10:13 pm
I don’t understand that. Why would argon not absorbing/emitting thermal IR allow the experimentalists to obtain 0.0K?
Well, you could start by looking at how atoms capture (absorb) IR. They absorb the energy mechanically, in the form of either stretching or bending or twisting of the molecular bonds, or rotation of the entire molecule. But argon, as a monatomic gas, has nothing to stretch or bend or vibrate. As a result, it cannot either absorb or emit IR. And it is symmetrical so there is no way to absorb energy by rotation.
There’s a reasonable discussion of this here, and more information here.
The main issue is the number of degrees of freedom of the gas molecule. Thermal IR doesn’t have enough energy to push electrons to higher orbits. It can only impart motion to the whole molecule. How much energy it can impart depends on the number and kind of degrees of freedom that the molecule has.
Now, if there are three atoms in the molecule, like CO2 or H2O, there are lots of ways that it can increase its energy. This is because such a molecule has a number of degrees of freedom. It can absorb energy because it is free to be rotated, or vibrated, or stretched, or any combination of these. It can absorb energy in all of those modes.
But argon is a symmetrical monatomic gas. It has only the basic three translational degrees of freedom, those of 3-D motion. It has no way to gain energy by vibration or rotation or stretching, simply because it cannot do a single one of those things.
You said earlier that everything emits and absorbs thermal IR, which is not true. However, it is true for any normal room-temperature solid, which is likely why it is so widely believed. And because it is true of solids, we can see solid things by observing their thermal infrared with “night vision” goggles.
And it is also true that many gases both absorb and emit thermal IR. Depending on their molecular geometry, so-called “greenhouse” gases can absorb IR by transforming it into rotation, or scissoring, or twisting, or a variety of energetic modes involving the molecular bonds as described in the citations above.
But argon simply cannot do that. It can’t stretch, scissor, or twist its molecular bonds, because it has no molecular bonds at all—it’s monatomic. And because it is symmetrical, it does not have rotational freedom. So it can’t absorb IR and transform it into rotation.
And as a result, argon is physically unable to absorb or emit thermal IR in the range of earth-like temperatures (below about 320K or so). Note that I am not saying that argon is a poor emitter/absorber of thermal IR at earth-like temperatures.
I am saying that argon simply has no physical mechanism by which it can absorb or emit thermal IR at those temperatures, so its IR emissivity in the relevant wavelengths is zero.
Best regards to you,
w.
PS—As Leif notes above, at high temperatures visible light can be absorbed and emitted by argon. This is because at high temperatures, visible light has enough energy to knock an argon electron into a different orbit, and it emits light when it drops back to its original orbit.
However, the energy in thermal IR at earth-like temperatures is a couple of orders of magnitude too weak to move an electron to a different orbit. Low-temperature thermal IR can only be absorbed as mechanical motion of some kind … and argon has no physical way to mechanically absorb or emit such thermal IR.
Willis said:
“So let us assume that we have the airless perfectly evenly heated blackbody planet that I spoke of above, evenly surrounded by a sphere of mini-suns. The temperature of this theoretical planet is, of course, the theoretical S-B temperature.”
I don’t believe I have ever disputed that.
I have simply pointed out that it cannot happen and there will always be uneven heating on a rotating, rough surfaced sphere illuminated from a point source. Even a surrounding sphere of exactly duplicated mini suns would have irregularities from the small spaces between them.
You seem to concede that uneven surface heating invalidates your assumptions so kindly answer my question.
Uneven heating must occur, air parcels at the surface must achieve varying densities as a result, gravity induces a decline in temperature and pressure with height, A convective circulation must ensue.
On that basis my contentions must be so, surely ?
A non radiative atmosphere both acquires thermal energy conductively from the surface on uplift and gives back thermal energy to the surface on descent.
Surface temperature rises but the radiative balance with space is not affected.
Willis: “Next, overall the ocean is receiving more energy than it radiates, so it is exporting energy … and the land is radiating more than it receives, so it is getting energy from the ocean”
I think this is a very important point that does not get enough analysis. I would say this sentence does invalidate Trenberth et al Earth energy diagram.
To my understanding the oceans do control much of the “Earth warming effect” that is attributed to greenhouse gases.
Attributing all the delta temperature to greenhouse gases and ignoring the oceans is the first in the CAGW list of errors=bad science.
The CAGW meme – the oceans would be frozen without greenhouse gases is stupid. The Earth is getting about 1000 W/m2 at the equator. No ocean would be frozen with that.
Furthermore the oceans are covered with many millions of sq kilometers of ice there where there is no sun, not losing heat through radiation or evaporation in those areas.
So the oceans are the first and most important climatic factor. Then come clouds.
Greenhouse gases come only after these.
Willis said:
” thermal IR can only be absorbed as mechanical motion of some kind … and argon has no physical way to mechanically absorb or emit such thermal IR.”
Work is done against gravity on uplift (cooling) and with gravity on descent (warmiing).
Thermal IR is indeed converted via work done to a higher surface temperature even beneath an Argon atmosphere.
The energy value of the conductive exchange may be net zero but the surface still warms, the S-B height rises and the radiative exchange with space is unaffected.
Willis Eschenbach says:
December 28, 2013 at 9:36 pm
Please follow the logic in the quote above, and you’ll see why adding a transparent GHG-free atmosphere to the planet in the thought experiment does not, and can not, exceed the S-B temperature no matter what the mechanism might be. If it could raise the temperature even one degree, the surface would be radiating on a continuous basis more than it is receiving … which is impossible.
An ocean with a frozen part may radiate in average the S-B temperature, however the average would be covering the frozen part – where the ocean does not radiate almost any + the unfrozen part.
So the unfrozen part will be radiating above the S-B temperature to compensate for the low thermal radiation that passes through ice.
Willis Eschenbach says, December 28, 2013 at 9:36 pm:
“Please follow the logic in the quote above, and you’ll see why adding a transparent GHG-free atmosphere to the planet in the thought experiment does not, and can not, exceed the S-B temperature no matter what the mechanism might be. If it could raise the temperature even one degree, the surface would be radiating on a continuous basis more than it is receiving … which is impossible.”
Of course it can. And it does. That’s how the Earth’s global surface attains its balmy temperature, way above the calculated S-B temperature. An atmosphere with no means of passing on its continuosly received energy (heat) to space would just make the surface hotter and hotter, until the point where the planet could no longer hold on to it and it would start gradually to be swept away.
Stephen has got this part completely wrong. The atmosphere wouldn’t or couldn’t in any isotropically heated scenario transfer any heat (energy) back to the surface, neither conductively nor radiatively. Heat only ever goes from hot to cold and the surface would forever remain warmer than the atmosphere, the former forever being the heat source of the latter.
A greater atmospheric weight on the surface simply makes it harder for an equal amount of energy per unit of time to move into the atmosphere through convection (and evaporation). And so, energy from the Sun absorbed by the surface would pile up and the temperature would correspondingly rise. The S-B equation has no bearing on this. It’s irrelevant. This is a real-world situation. With an atmosphere. And with a temperature gradient established from the surface out. It’s all about the system’s heat capacity. How much energy will accumulate? The more energy piled up over a certain period of time, the warmer the surface will be … It’s all about the asymmetry between IN and OUT.
A heavy atmospere requires a higher mean surface temperature to maintain balance between the rates of energy absorbed and energy shed than a lighter atmosphere. Because it affects the rate of air movement up along the set temperature gradient. And how many molecules will escape the surface per unit of time through evaporation.
Kristian said:
“Stephen has got this part completely wrong. The atmosphere wouldn’t or couldn’t in any isotropically heated scenario transfer any heat (energy) back to the surface, neither conductively nor radiatively. Heat only ever goes from hot to cold and the surface would forever remain warmer than the atmosphere, the former forever being the heat source of the latter.”
Noted and agreed. I corrected that in a response to Konrad in another thread as follows:
“It is not necessary for conduction by air to a colder surface to achieve net warming of that surface
All that is necessary is:
i) A surplus of incoming radiation over outgoing radiation where illumination is full on. The disparity being caused by conduction to the air.
ii) A reduction in the rate of outgoing radiation elsewhere to a level lower than would have been the case for a surface with no atmosphere. The disparity being caused by the insulating effect of adiabaically warmed descending air.
The energy engaged does not have to be large because the bulk of energy passing through is undisturbed.
All that is necessary is that there be SOME diversion of energy throughput via conduction to convective overturning and whatever the amount of that diversion the average global surface temperature will rise proportionately.
On Earth that is about 33 C.
That proportion is determined by mass and not radiative capability.”
Kristian said:
“Heat only ever goes from hot to cold and the surface would forever remain warmer than the atmosphere, the former forever being the heat source of the latter.”
Where there is reduced illumination the surface is generally colder than the air.
If the air is calm then an inversion layer will develop but mostly there is enough wind to prevent that in which case the air remains warmer than the ground and the adiabatically warmed air reduces the cooling rate of the ground.
Evaporation is a lubricant for the system and best left out at this stage.
Mario Lento says:
December 28, 2013 at 6:47 pm
“I’m just enjoying reading through this post and I have a nit to pick. ”
———————–
But you picked the wrong nit ….. when you chose that one, …. didn’t you?
Because Willis said: ““pressure heads” are those that think that on a planet with a GHG-free atmosphere, say an argon atmosphere,”
Which you referenced as an excuse for what you posted, to wit: “All astronomers are then ‘pressure heads’ as it is generally accepted that pressure alone heated the Sun,”
There is no “are then” relationship because your comment defined a new “subject”, the Sun. Thus an “out-of-context” response, me thinks.
Stephen Wilde says:
December 28, 2013 at 1:02 pm
“Agreed, hence my short follow up post at 2.01am”
———————–
I seen that but posted anyway ….. because my posting provides me a “direct link” back to that “point” in the discussion to begin reading “new postings” that were added following my post.
Anyway, the following statement is an important fact which discredits and/or negates the claims associated with the so called “greenhouse effect” of CAGW, to wit:
“the mass induced increase in near-surface air temperatures is primarily the result of the interaction of atmospheric mass with the heated surface”
The above statement explains the extremely quick increase/decrease in near-surface air temperatures in desert areas (Sahara, Gobi, US Southwest) of extremely low H2O vapor ppm (humidity) ….. or, …. explains the lack of any residual air temperatures associated with the so called “greenhouse effect” of CAGW in said desert areas due to the presence of 398+- ppm of atmospheric CO2.
Thus, the above said proves that the current quantity (398+- ppm) of atmospheric CO2 has no measurable effect on the temperature of the near-surface atmosphere at any locale on the earth’s surface. IMHO, atmospheric CO2 would have increase to more than 10,000 ppm before there was a measurable affect on near-surface temperatures.
Willis 11:39pm: Thanks, interesting write-up, my congrat.s to the writer.
However, there are some issues and questions to look into. The write-up doesn’t provide a cite. So I will try to look further into the assertions. I will try to keep it short. I won’t succeed in complete shortness other than to state the 11:39pm write-up fails text book Planck’s law & IGL.
“I don’t understand that. Why would argon not absorbing/emitting thermal IR allow the experimentalists to obtain 0.0K?”
They would just use Ar as the working fluid and if it were true no emission or absorption were physical for Ar then they could get to 0.0K since no emission or absorption would be occurring but as all “mass spontaneously and continuously emits radiation over the entire spectrum as described by Planck’s Law.. 0.0K is impossible as they cannot get to 0 entropy. Ever.
2) Willis writes: Well, you could start by looking at how atoms capture (absorb) IR. They absorb the energy mechanically, in the form of either stretching or bending or twisting of the molecular bonds…”
In this statement Willis confuses atoms and molecules. I suppose meaning is “…start by looking into how molecules capture (absorb) IR.” All well and good. Concur.
3)The writer: “You said earlier that everything emits and absorbs thermal IR, which is not true.”
This IS true for all mass including gases as I wrote including Ar in text books, see Planck’s Law discussions in texts and in particular p. 118 in Bohren 1998.
Then the writer: “And it is also true that many gases both absorb and emit thermal IR.”
These 2 statements by the writer are extrapolated to a collision at 0.0K. Both cannot be true.
I also cite Bohren 2006 for a wonderful discussion right up front. Apply this warning label though: This is true to the extent classical mechanics is true. Using theorems, physical laws, and suchlike outside the intended range may be dangerous to your mental health.
Why is this always “on” emission & absorption true for all gas and in particular an ideal gas?
Short story answer: As written Ar IS monatomic gas, an Ar atom can be considered as a point mass with avg. KE of a gas atom 3*k*T/2. As T tends to 0.0K implies motion stops (meaning avg. v^2 tends to 0.0). This implies through ideal gas law (IGL) that the volume of an ideal gas would vanish at very low temperatures, but such volume cannot go to 0.0. See Bohren 1998 p. 52. (k=Boltzmann’s constant.)
Conclusion: In context of the magnificent climate heat engine, true classical mechanics means even a cold Ar retained gaseous atmosphere added to a rock in space would absorb & emit IR raising the surface Tmean of rock above that of vacuum S-B.
Just as lsvalgaard writes 7:37pm this thread.
Stephen 4:07am: “On Earth that is about 33 C. That proportion is determined by mass and not radiative capability.”
Both, drop the “not”. Correct conclusion + wrong physics = bad science.
As I’ve been suggesting to you quite awhile, consult a good atm. radiation text for why “mass and radiative capability” are linked by Planck’s law. The one built on no less than 3 fundamental constants of nature. Einstein showed us mass is linked to energy by speed of light which is radiation. If there is mass in the control volume of interest greater than 0K and all real CVs with mass are Tmean greater than 0K, there is radiation emission and absorption according to corpus of Max Planck’s work.
Get cracking on that reading assignment. Nose in text book. Do it now. Reading the science basics is good for you. It is not necessary to know differential calculus, Bohren 1998 avoids it well enough, to extent possible using just discussion.
Samuel C Cogar says:
December 29, 2013 at 5:14 am
Mario Lento says:
December 28, 2013 at 6:47 pm
“But you picked the wrong nit ….. when you chose that one, …. didn’t you?
Because Willis said: ““pressure heads” are those that think that on a planet with a GHG-free atmosphere, say an argon atmosphere,”
Which you referenced as an excuse for what you posted, to wit: “All astronomers are then ‘pressure heads’ as it is generally accepted that pressure alone heated the Sun,”
There is no “are then” relationship because your comment defined a new “subject”, the Sun. Thus an “out-of-context” response, me thinks.
++++++++++++++
A nit that I picked was stated here and was not responding to anything else. That’s why I called it picking a nit –picking a specific piece of an argument make by Leif. I wrote:
“I think what Willis is saying (correctly) [and these are my words] is that pressure does not cause the heating so much as it changes the temperature. However, that change in temperature is not new energy being created –rather its energy from somewhere else being concentrated such as to raise the temperature where there is more pressure.”
That nit is all I was asking about, and that nit is valid although I could be incorrect. I don’t like calling names, so was not speaking of pressure heads per se.
Stephen Wilde says:
December 29, 2013 at 3:13 am
Sorry, but that’s not possible with a transparent argon atmosphere. If the surface temperature rises, the radiation to space will also rise.
Regards,
w.
Kristian says:
December 29, 2013 at 4:00 am
On the Earth, you are right when you say “of course it can”. This is because the GHGs can absorb some of the radiation.
But in my thought experiment, with a transparent argon atmosphere … well, no, it can’t.
w.
Willis: Doesn’t Argon have heat capacity? Is so, it would require some energy to be at some temperature above 0K. But if it can have heat, it must absorb heat, and that also makes it able to lose or share heat. Is it all convective, and as such picks up no heat due to radiant energy?
Mario/AKA fanboy (stated only to aggravate the very few degenerates)
Mario Lento says:
December 30, 2013 at 11:06 pm
Thanks, Mario. Certainly argon can pick up and lose heat, by conduction and convection. However, what it is not physically capable of doing is either absorbing or emitting thermal IR.
w.
Willis said:
“That’s not possible with a transparent argon atmosphere. If the surface temperature rises, the radiation to space will also rise.”
How does one account for the energy required for the conductive exchange between surface and air ?
Note that the mass of the air doesn’t need to actively conduct back to the surface, all it needs to do is slow down cooling of the surface by bringing adiabatically warmed air back down to the surface.
The Argon atmosphere is held off the ground by conduction and the consequent convective overturning.
The heat at the surface has to account for both radiative balance with incoming energy AND a continuing exchange of energy with the mass of the air.
As long as an atmosphere is being held off the ground the surface must be warmer than S-B if both functions are to be performed.
The mass of an atmosphere simply raises the S-B height off the ground.
If radiative capability within the atmosphere is introduced then the effective radiating height rises off the ground.
Two entirely separate processes, one mechanical and the other radiative.
@Willis and Stephen:
December 31, 2013 at 1:41 am
+++++++++++
Please bear with me.
In TIG (tungsten inert gas) welding, the arc is typically an Argon plasma and is more specifically referred to as GTAW (gas tungsten arc welding) when Argon is the inert gas, Argon certainly radiates heat at those temperatures. But assuming that it is not able to radiate heat or be heated by radiation as weak as that which reaches our planet, I go through the following thought process with that assumption (fact?).
On a mythical planet 92 millions miles from a sun like ours:
If it is true that Argon cannot gain energy through irradiation, then an Argon atmosphere will do nothing to the energy budget of the planet –maybe. It’s atmospherica mass will certainly share in the energy stored on the planet (because it warms through conduction and spreads through convection) but the net energy of the planet will be the same with or without the Argon –maybe. So if the Argon mass were gone, and replaced by more of the surface with the exact same albedo, there would be no difference in overall energy retained by the planet –again I say maybe.
That said, since the Argon mass receives conductive and convective energy from the surface that does collect heat through irradiance, the heat distribution will be different than there being no Argon atmosphere. Some of that energy will be floating around at some significant thin layer around the planet not radiating anything.
I think the surface “temperature” of a planet with an Argon atmosphere would be different than the surface temperature of an otherwise similar planet with no atmosphere at all. At least because some of the convected energy is stored in the Argon atmosphere and not on the surface.
The question might be asked; Can an Argon atmosphere lose energy to space since it cannot exchange energy through radiation? It cannot, from what I think is true about Argon on a mythical planet 92 million miles away from our sun. Only the surface will radiate heat into space, passing straight through the Argon as if it were not there.
Finally here’s my question. If only the surface can radiate energy to space, passing through the Argon atmosphere, wouldn’t there be less heat radiated into space because of a lower surface temperature?
Perhaps I got a whole lot of facts wrong, because now I am confused.
Mario,
That is a helpful summary and serves to show how easily confusion can arise.
It may help if I summarise what I think happens in the real world:
i) As soon as an atmosphere starts to form its mass lifts off the surface taking conducted energy with it. Obviously, that conducted energy is initially derived from absorbed radiation at the surface.
ii) The surface temperature drops whilst the atmosphere is forming but, because incoming radiation stays the same, equilibrium is soon restored by virtue of the fact that, during the process of forming the atmosphere, energy out is less than energy in due to the (temporarily) lower surface temperature.
iii) At that point we have the surface at the same temperature as before with overall radiative equilibrium but at the same time there is then an additional store of energy in the atmosphere.
iv) That energy in the atmosphere is then adiabatically recycled between the bottom and top of the atmosphere (mostly the troposphere for Earth) so as to provide the energy needed to maintain the height of the atmosphere.
v) The net radiative effect of the adiabatic exchange is zero because all kinetic energy leaving the surface by conduction and convection via uplift is matched by kinetic energy returned to the surface by the subsequent descent.
vi) However, at all times at the surface, that additional conducted energy is present in the temperature of the air just above the surface which has an insulating effect.that must raise the average surface temperature above S-B.
vii) The height at which S-B is satisfied must rise off the surface purely as a result of the conductive / convective process which is caused by mass held within a gravitational field and not by radiative capability.
One has to get the correct sequence of events and then it becomes clear to me but, apparently, not to others.
Radiative gases are not necessary for any part of that purely mechanical process.
“Finally here’s my question. If only the surface can radiate energy to space, passing through the Argon atmosphere, wouldn’t there be less heat radiated into space because of a lower surface temperature?”
Uh “No”, …. the lower surface temperature is the result of the heat (IR) not being re-radiated back toward the surface.
A real life example of said is a desert environment of extremely low humidity (H2O vapor) when the daytime near-surface air temperatures quickly cool down as soon as the Sun starts to “set” below the horizon.
The temperature can be 110F or greater at noon time and quickly drop to 32F or below at night time because there is not enough ppm of either H2O vapor or CO2 in the air to absorb the IR from the surface and re-radiate a small part of it back toward the surface to maintain the warmer temperatures for very long.
It abides by the … Law of Diminishing IR Returns. 🙂 🙂 The less the ppm the less the IR returns.
Willis 10:56 pm: “This is because the GHGs can absorb some of the radiation. But in my thought experiment, with a transparent argon atmosphere … well, no, it can’t.”
An argon atmosphere isn’t transparent. Here’s why I can write that simply and no simpler:
Two argon atoms traveling in earth’s atm., one behind the other from POV of an incoming IR photon from sun. The photon slams into the nearest atom and suffers annihilation, the Ar atom still exists. The photon behind is in the “shade” of this process.
The atom that annihilated the photon now has added momentum of that photon, the one behind has no change in momentum from the photon. Earth’s atm. certainly was not transparent to that poor IR photon annihilated by the Ar atom.
It continues astonish me that posters won’t check the basic text books when challenged on a physical process. Here I will cite the online Caballero text book sec. 5.8 “Extinction and Optical Path” p. 115.
Willis IS correct with text books (as I concurred) in that the Ar atom had no vibrational IR absorption/emission capability as does its polyatomic molecular gas atm. constituents.