Guest Post by Willis Eschenbach
Since at least the days of Da Vinci, people have been fascinated by perpetual motion machines. One such “perpetuum mobile” designed around the time of the civil war is shown below. It wasn’t until the development of the science of thermodynamics that it could be proven that all such mechanisms are impossible. For such machines to work, they’d have to create energy, and energy cannot be either created or destroyed, only transformed.
I bring this up for a curious reason. I was reading the Jelbring hypothesis this afternoon, which claims that greenhouse gases (GHGs) are not the cause of the warming of the earth above the theoretical temperature it would have without an atmosphere. Jelbring’s hypothesis is one of several “gravito-thermal” theories which say the heating of the planet comes from gravity rather than (or in some theories in addition to) the greenhouse effect. His thought experiment is a planet with an atmosphere. The planet is isolated from the universe by an impervious thermally insulating shell that completely surrounds it, and which prevents any energy exchange with the universe outside. Inside the shell, Jelbring says that gravity makes the upper atmosphere colder and the lower atmosphere warmer. Back around 2004, I had a long discussion on the “climateskeptics” mailing list with Hans Jelbring. I said then that his theory was nothing but a perpetual motion machine, but at the time I didn’t understand why his theory was wrong. Now I do.
Dr. Robert Brown has an fascinating post on WUWT called “Earth’s baseline black-body model – a damn hard problem“. On that thread, I had said that I thought that if there was air in a tall container in a gravity field, the temperature of the air would be highest at the bottom, and lowest at the top. I said that I thought it would follow the “dry adiabatic lapse rate”, the rate at which the temperature of dry air drops with altitude in the earth’s atmosphere.
Dr. Brown said no. He said that at equilibrium, a tall container of air in a gravity field would be the same temperature everywhere—in other words, isothermal.
I couldn’t understand why. I asked Dr. Brown the following question:
Thanks, Robert, With great trepidation, I must disagree with you.
Consider a gas in a kilometre-tall sealed container. You say it will have no lapse rate, so suppose (per your assumption) that it starts out at an even temperature top to bottom.
Now, consider a collision between two of the gas molecules that knocks one molecule straight upwards, and the other straight downwards. The molecule going downwards will accelerate due to gravity, while the one going upwards will slow due to gravity. So the upper one will have less kinetic energy, and the lower one will have more kinetic energy.
After a million such collisions, are you really claiming that the average kinetic energy of the molecules at the top and the bottom of the tall container are going to be the same?
I say no. I say after a million collisions the molecules will sort themselves so that the TOTAL energy at the top and bottom of the container will be the same. In other words, it is the action of gravity on the molecules themselves that creates the lapse rate.
Dr. Brown gave an answer that I couldn’t wrap my head around, and he recommended that I study the excellent paper of Caballero for further insight. Caballero discusses the question in Section 2.17. Thanks to Dr. Browns answer plus Caballero, I finally got the answer to my question. I wrote to Dr. Brown on his thread as follows:
Dr. Brown, thank you so much. After following your suggestion and after much beating of my head against Caballero, I finally got it.
At equilibrium, as you stated, the temperature is indeed uniform. I was totally wrong to state it followed the dry adiabatic lapse rate.
I had asked the following question:
Now, consider a collision between two of the gas molecules that knocks one molecule straight upwards, and the other straight downwards. The molecule going downwards will accelerate due to gravity, while the one going upwards will slow due to gravity. So the upper one will have less kinetic energy, and the lower one will have more kinetic energy.
After a million such collisions, are you really claiming that the average kinetic energy of the molecules at the top and the bottom of the tall container are going to be the same?
What I failed to consider is that there are fewer molecules at altitude because the pressure is lower. When the temperature is uniform from top to bottom, the individual molecules at the top have more total energy (KE + PE) than those at the bottom. I said that led to an uneven distribution in the total energy.
But by exactly the same measure, there are fewer molecules at the top than at the bottom. As a result, the isothermal situation does in fact have the energy evenly distributed. More total energy per molecules times fewer molecules at the top exactly equals less energy per molecule times more molecules at the bottom. Very neat.
Finally, before I posted my reply, Dr. Brown had answered a second time and I hadn’t seen it. His answer follows a very different (and interesting) logical argument to arrive at the same answer. He said in part:
Imagine a plane surface in the gas. In a thin slice of the gas right above the surface, the molecules have some temperature. Right below it, they have some other temperature. Let’s imagine the gas to be monoatomic (no loss of generality) and ideal (ditto). In each layer, the gravitational potential energy is constant. Bear in mind that only changes in potential energy are associated with changes in kinetic energy (work energy theorem), and that temperature only describes the average internal kinetic energy in the gas.
Here’s the tricky part. In equilibrium, the density of the upper and lower layers, while not equal, cannot vary. Right? Which means that however many molecules move from the lower slice to the upper slice, exactly the same number of molecules must move from the upper slice to the lower slice. They have to have exactly the same velocity distribution moving in either direction. If the molecules below had a higher temperature, they’d have a different MB [Maxwell-Boltzmann] distribution, with more molecules moving faster. Some of those faster moving molecules would have the right trajectory to rise to the interface (slowing, sure) and carry energy from the lower slice to the upper. The upper slice (lower temperature) has fewer molecules moving faster — the entire MB distribution is shifted to the left a bit. There are therefore fewer molecules that move the other way at the speeds that the molecules from the lower slice deliver (allowing for gravity). This increases the number of fast moving molecules in the upper slice and decreases it in the lower slice until the MB distributions are the same in the two slices and one accomplishes detailed balance across the interface. On average, just as many molecules move up, with exactly the same velocity/kinetic energy profile, as move down, with zero energy transport, zero mass transport, and zero alteration of the MB profiles above and below, only when the two slices have the same temperature. Otherwise heat will flow from the hotter (right-shifted MB distribution) to the colder (left-shifted MB distribution) slice until the temperatures are equal.
It’s an interesting argument. Here’s my elevator speech version.
• Suppose we have an isolated container of air which is warmer at the bottom and cooler at the top. Any random movement of air from above to below a horizontal slice through the container must be matched by an equal amount going the other way.
• On average, that exchange equalizes temperature, moving slightly warmer air up and slightly cooler air down.
• Eventually this gradual exchange must lead to an isothermal condition.
I encourage people to read the rest of his comment.
Now, I see where I went wrong. Following the logic of my question to Dr. Brown, I incorrectly thought the final equilibrium arrangement would be where the average energy per molecule was evenly spread out from top to bottom, with the molecules having the same average total energy everywhere. This leads to warmer temperature at the bottom and colder temperature at elevation. Instead, at thermal equilibrium, the average energy per volume is the same from top to bottom, with every cubic metre having the same total energy. To do that, the gas needs to be isothermal, with the same temperature in every part.
Yesterday, I read the Jelbring hypothesis again. As I was reading it, I wondered by what logic Jelbring had come to the conclusion that the atmosphere would not be isothermal. I noticed the following sentence in Section 2.2 C (emphasis mine):
The energy content in the model atmosphere is fixed and constant since no energy can enter or leave the closed space. Nature will redistribute the contained atmospheric energy (using both convective and radiative processes) until each molecule, in an average sense, will have the same total energy. In this situation the atmosphere has reached energetic equilibrium.
He goes on to describe the atmosphere in that situation as taking up the dry adiabatic lapse rate temperature profile, warm on the bottom, cold on top. I had to laugh. Jelbring made the exact same dang mistake I made. He thinks total energy evenly distributed per molecule is the final state of energetic equilibrium, whereas the equilibrium state is when the energy is evenly distributed per volume and not per molecule. This is the isothermal state. In Jelbrings thought experiment, contrary to what he claims, the entire atmosphere of the planet would end up at the same temperature.
In any case, there’s another way to show that the Jelbring hypothesis violates conservation of energy. Again it is a proof by contradiction, and it is the same argument that I presented to Jelbring years ago. At that time, I couldn’t say why his “gravito-thermal” hypothesis didn’t work … but I knew that it couldn’t work. Now, I can see why, for the reasons adduced above. In addition, in his thread Dr. Brown independently used the same argument in his discussion of the Jelbring hypothesis. The proof by contradiction goes like this:
Suppose Jelbring is right, and the temperature in the atmosphere inside the shell is warmer at the bottom and cooler at the top. Then the people living in the stygian darkness inside that impervious shell could use that temperature difference to drive a heat engine. Power from the heat engine could light up the dark, and provide electricity for cities and farms. The good news for perpetual motion fans is that as fast as the operation of the heat engine would warm the upper atmosphere and cool the lower atmosphere, gravity would re-arrange the molecules once again so the prior temperature profile would be restored, warm on the bottom and cold on the top, and the machine would produce light for the good citizens of Stygia … forever.
As this is a clear violation of conservation of energy, the proof by contradiction that the Jelbring hypothesis violates the conservation of energy is complete.
Let me close by giving my elevator speech about the Jelbring hypothesis. Hans vigorously argues that no such speech is possible, saying
There certainly are no “Elevator version” of my paper which is based on first principal physics. It means that what I have written is either true or false. There is nothing inbetween.
Another “gravito-thermal” theorist, Ned Nikolov, says the same thing:
About the ‘elevator speech’ – that was given in our first paper! However, you apparently did not get it. So, it will take far more explanation to convey the basic idea, which we will try to do in Part 2 of our reply.
I don’t have an elevator speech for the Nikolov & Zeller theory (here, rebuttal here) yet, because I can’t understand it. My elevator speech for the Jelbring hypothesis, however, goes like this:
• If left undisturbed in a gravity field, a tall container of air will stratify vertically, with the coolest air at the top and the warmest air at the bottom.
• This also is happening with the Earth’s atmosphere.
• Since the top of the atmosphere cannot be below a certain temperature, and the lower atmosphere must be a certain amount warmer than the upper, this warms the lower atmosphere and thus the planetary surface to a much higher temperature than it would be in the absence of the atmosphere.
• This is the cause of what we erroneously refer to as the “greenhouse effect”
Now, was that so hard? It may not be the best, I’m happy to have someone improve on it, but it covers all the main points. The claim that “gravito-thermal” theories are too complex for a simple “elevator speech” explanation doesn’t hold water.
But you can see why such an elevator speech is like garlic to a vampire, it is anathema to the “gravito-thermal” theorists—it makes spotting their mistakes far too easy.
w.
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Same answer as I gave early in the “Matter of Gravity” post on January 14, 2012 at 2:45 am
Your argument about a heat engine using heat difference not working has been countered by the Norwegians who had a power station off coast in the Atlantic using the heat difference between water layers. It produced 60Mw, until the first severe winter storm when it sunk without trace.
The gravitic heat is better called adiabatic heat by compression which does exist and is the principle used by many machines used daily by everybody. It would happen in a planetary atmosphere because that is open to space and has free movement to all sides. there would be vertical movement due to convection and atmospheric pumping between day and night sides due to temperature difference/heat loss rates. Also your column, despite being at the same temperature, would not have the same heat content at the top compared to the bottom because gravity would introduce a density differential, A Km high enclosed column of air does NOT represent an atmospheric column by any stretch of the imagination.
I also ask my Jupiter question again. Why does this gas giant radiate more heat than it receives from the sun. your argument above makes this impossible.
My reply to all the questions raised above on both sides is WWES…….What Would Einstein Say? I would genuinely like to know. I wonder if he would have enjoyed these blogs. Anyone channel him lately?
“George Turner says:
January 19, 2012 at 9:20 pm
I have a follow-up thought experiment to my previous comment.
If flipping the air column upside down doesn’t require an input of work and returns the column to the dry adiabatic lapse rate, then the dry adiabatic lapse rate must be the column’s thermal equilibrium because a system cannot be shifted from thermal equilibrium without an input of work.”
I am sure what would happen. It seems you going heat the top when reaches bottom- and that heat isn’t going to get back to the new top.
Let’s move to orbit, where you could spin it [forever], and you have gravity gradient- the length column will make lower part travel slower than upper part. You will have gravity- gravity gradient in “free fall”.
Of course spinning will also add artificial gravity.
As I said you will heat the lower end- and therefore cool the gas.
So how a way to cool gas.
Now, let’s insulate it somehow.
Hmm. Use water instead of gas.
So without spinning water will cover entire inside [water tension] and will end up at lower end, mostly. Start slow rotation, and water will run to to middle then new bottom.
It seems that will affect the orbit somehow:).
But question is whether cools.
It doesn’t seem to. Back to air.
A new question is how fast would air move.
It’s going to fall, so it’s going to move fairly fast.
So back to surface again [or be some orbit and have respectable amount gravity gradient-big column]
The vacuum end when rotates to ground will “suck” the heavier air
and heavier air will fall- and this is going to be violent- as in supersonic.
So, there will be good mixing of the air- because the hot air going go straight up,
or break your machine.
You going to cause the air to become more directed.
It seems is you made air more balance in it’s direction- every molecule stopped another other molecule you get colder temperature.
But seems that if you start with cold air you could get hot air- and the more vacuum the better:).
One problem is normal atmospheric air isn’t balanced in terms of weight- the bottom is a lot heavier than the top.
So work is being done by rotating it.
So question is how small can make this thing and have do something. 1 km long seems challenging. But if used colder air and have vacuum at top, it seems something smaller is possible.
If it was 5 km in length falling velocity is somewhere around 500 mph, which somewhat interesting- but smaller are going make a little bit of wind. So entire atmosphere excitement, and 5 km maybe somewhat interesting, but probably something even bigger in space environment and using gravity gradient- might actually do something useful..
Your first thought experiment sounded like Mawells Demon in which a gas can be partitioned into a hot side and a cold side by a force (a demon) that only allows high kinetic energy molecules to move in one direction and excluded the slow ones. In this case gravity is the demon.
I still don’t like your “perpetuum mobile” argument and a claim it violates the law of conservation.
I am not a physicist, but instead a logician. As I understand it physics claims energy cannot be destroyed. Thus it cannot be used up just converted and lost.
Jelbrings model according to my reading encapsulates energy and does not allow any to exit the atmosphere. So while you talk about light forever, if that energy is manifested as light and its always light where does it go when it cannot go anywhere?
Logically it seems to me the only issue is whether the atmosphere would be isothermal or not.
If isothermal then Jelbring is wrong and gravity does not cause the lapse rate and if the lapse rate exists at internal equilibrium he is most likely right.
I tend to think, but could be wrong, that for molecules under less pressure with the same temperature need to contain more energy.
So the question is what equilibrium is, is it energy or is it temperature. Personally I like the basal concept that its energy and not temperature but I have not wrapped my mind, or perhaps warped it, with Caballero.
There are some terrific quotes by Richard Feynman in his Nobel Lecture The Development of the Space-Time View of Quantum Electrodynamics, that bear on these issues of thermodynamics:
What we teach our engineering students is that you don’t really understand a phenomenon until (1) you can analyze it in more than one framework (formalism), and (2) within each framework, you can present it as an picture, an equation, and a numerical computation, and (3) you are able to unite all these frameworks within an encompassing narrative, that dovetails with other folks’ time-tested narratives.
With regard to thermodynamics and transport theory (which is broadly what this WUWT topic is about), an historically recent and very broadly applicable framework regards thermodynamics and transport theory as (essentially) the study of the geometry of flow on manifolds, specifically the study of Hamiltonian dynamical flows on manifolds that are equipped with a symplectic structure.
One great virtue of the symplectic approach to thermodynamics and transport is that it naturally encompasses both classical and quantum dynamics. A pretty significant downside, though, is that it takes a full year to learn the basic ideas and notations of differential geometry, in terms of which the whole framework is given.
What the resulting geometric dynamical frameworks predicts, though, is simple. If we computationally model the atmosphere (by a brute-force numerical calculation of molecular dynamics) as a cloud of particles in a gravitational potential, such that the particles bounce off each other elastically (with each collision conserving both energy and the number of particles), and the distance between collisions is small compared to the height of the atmosphere, and we do not “stir” the atmosphere with radiation heating at the bottom (or allow any other external influence to do work on the particles), then we will find (from the brute-force numerical codes) that the kinetic temperature of the particles is constant from top-to-bottom (note: the Wikipedia page the kinetic theory of gases has a picture of this kind of simulation, which are described in-depth in the well-respected textbook by Frenkel and Smit, titled Understanding Molecular Simulation: from Algorithms to Applications).
The dynamical geometer will argue as follows:
Summary: The folks here on WUWT who conceive that the gravitational potential gradient of the earth’s atmosphere has to induce some kind of thermodynamic gradient are 100% correct—but that thermodynamic gradient is a gradient of pressure (or equivalently, of chemical potential), not of temperature.
If these ideas sound kind of complicated and subtle … well, they are! Mistakes are very easy to make, and that is why it is prudent to evolve multiple independent explanations (pictures, analysis, numerics) as a cross-check on any given calculation.
A final thought when you have an equilibrium you need energy to change it. Thus our Stygian friends cannot tap into the equilibrium and generate light, they need energy to throw it out of equilibrium or if that energy is manifested as light to change the lighting arrangement concentrate it, focus it, or do any work with it.
re perpetual motion machines, we can say that there is ‘perpetual’ motion in our universe, such as orbits, bigband expansions and the like. how many motions are we undergoing at the moment ? 5 ?
If it’s energy for work you are seeking, then the best perpetual producer of energy on our planet might be it’s magnetic field. the findings of Nikola Tesla are to be considered. wiki has a reasonable summary. I am led to believe that I can access the electrical differential between 2 points separated by height, enough for a domestic supply.
my view is that there is much to be said for domestic solutions to energy requirements, passive solutions in the main.
getting back to the flow of energy, matter, temperature and gas atmospheres, bottled and otherwise.
heat is associated with increased molecular activity, ditto for pressure and molecular activity. we have bonding processes, chemical aggregations, there’s an evolution of structure. certainly our systems are extremely dynamic (large energy packages) with a myriad of structures – guess a number.
entropy – the eventual breakdown of structure and atoms. our little atom no longer has the energy to maintain it’s structure. pop ! it stops, electrons touch protons and neutrons, probably losing their shape. the molecular structure loses it’s space, and the volume of the matter reduces by a massive amount. in our astronomy class we would marvel at how a battleship could fit into a matchbox if you removed the space between the atoms. so we can ‘witness’ the reduction of volume at the earth’s core, I don’t know the pressure or gravitational measurements at that place, nor electrical discharge. obviously the process depletes the fuel source and imploding occurs. so we are supported from below as well as from above.
I do believe in using a multivariable approach to solving problems, rather than isolating certain variables.
I think we can generally expect more of the same; cosmic rays, sun bursts, volcanic eruptions, convection currents, and the odd meteorite.
cheers !
anna v says:
January 19, 2012 at 10:36 pm
“Could one do the experiment using water as the fluid?”
Yes, you could, but there is no need. We already have some; they are called oceans and lakes. The water at the bottom of the ocean is under great pressure. Dos this make it warmer? No, we all know that warm water rises. The hotter water is at the top. You can verify that in your bathtub. So pressure does not cause warming. QED.
So what is the difference between water and the atmosphere? We all know that warm air rises too, just like warm water rises. But in the atmosphere the cold temperatures are at the top ( up to the tropopause). So what is different? I could indicate this in one word! – but it is best left as an exercise to the reader. Some individual thought will promote a more general understanding.
What Bart said.
As others have observed above, Willis’s argument has a then-a-miracle-occurs step: he postulates a heat engine that is free of the gravity to which the gas column is subjected. He skipped the the step where Harry Potter removes the gravity from the heat engine’s location.
The mean single-molecule kinetic energy in a system of the type Willis describes is (3E/(5N-2))(1-mgz/E), where N is the number of molecules, E is total system energy, m is molecular mass, g is the acceleration of gravity, and z is altitude. If you put numbers to it, you see that the lapse rate is exceedingly small but non-zero.
Imagine Willis’ container to be finite, and filled with air with a pressure of 1 bar, and being in his isothermal condition, with constant pressure and temperature throughout, as required by the Ideal Gas law. Now consider a second container on topo of it, with infinitesimal height, with vacuum inside. Now we remove the lid that separates these two containers. Brownian motion will make gas molecules dissipate into the vauum but the gravitational field pulls them back; and a pressure gradient develops, and with it, according to the Ideal Gas law, a temperature gradient.
And that is the stable configuration, not the isothermal one. What we end up with is the dry lapse rate, assuming that we have no radiative energy redistribution.
The notion that in equilibrium, there must be the same density of kinetic and potential energy in every partial volume must be false, because it would require infinite temperatures at the top end of the gas column.
I failed to mention that the formula I gave above applies to monatomic gases.The factor on the right is different for gases with higher degrees of freedom, but the overall expression remains dependent on altitude.
Another never ending debate is seems. How about escape velocity?
The atmosphere of a planet cannot be completely isothermal since the velocity i.e. energy of the uppermost molecules at some point would exceed escape velocity. Venus and Earth both have roughly the same mass so they would have the same escape velocity. If Venus is a perfect greenhouse effect, since its black body temperature is 184K (65Wm-2) or -89C, the Earth would have the same constraints, -89C, Anyone noticed the minimum temperature of the Antarctic lately?
Gravity places limits on atmospheric energy, if gravity fluctuates it would change those limits. Earth’s gravity doesn’t fluctuate enough to have a significant impact on temperature at the surface. If someone would like to show that Earth’s escape velocity changes enough to have an impact on surface temperature, I would love to see it.
Since mass is energy, Gravity and the Geomagnetic field both help retain atmospheric mass, perhaps a mass balance would be an interesting exercise?
This argument should be possible to resolve in 5 min by any reputable physics professor.
So why not invite one (or several) to comment/clarify?
In 2010 I had a discussion about Hans Jelbrings theory with John Wallace, atmospheric scientist at the university of Washington. He wrote me:
“To understand how radiative transfer influences surface temperature, one needs to go beyond the concept of the adiabatic lapse rate and consider an atmosphere in “radiative-convective equilibrium, as discussed on p. 421-422 of the 2nd edition of our textbook. In such an idealized 2-layer atmosphere, the lower layer, which is comparable in depth to the troposphere, has a lapse rate equal to the adiabatic lapse rate . Two points emerge from this simple analysis:
(1) Were there is no greenhouse effect, the lapse rate in a planetary atmosphere would be isothermal (i.e., temperature would not change with height. In this case, the dry adiabatic lapse rate would be unchanged from its present value, but it would be completely irrelevant to the interpretation of the observed lapse rate.
(2) Greenhouse gas concentrations have no effect on the adiabatic lapse rate in the lower “convective” layer, but they determine the depth of that layer: increasing greenhouse gases increases the surface temperature of the planet not by changing the lapse rate, but by deepening the convective layer. “.
I think that’s it.
There is a difference between temperature and heat. whilst temperature is a measurement of heat we need to know the specific heat of a substance to know how much heat is present. So this imaginary Km high column could have identical temperatures top and bottom but heat content will be different due to the density difference.
I think I have said this before. Sorry for a boring repeat.
Hi Willis,
I am pleased that you have retruned to this.
First, something I said on the previous thread was both hasty and in error. In terms of Potential Energy the change from isothermal and the DALR modes does not lower the centre of mass of the atmosphere as I speculated, it is not energetically prefered as I suggested, in fact it makes no difference as far as I can tell. Now on to more interesting things.
As I see it, you now expose their model as being inviolation of both the 1st and 2nd Laws. That is the way I have seen things.
Having derived the isothermal as being the prefered profile, a way is open to you to do something rather useful, in my opinion. That is to determine the GHE without appeal to the notion of “heat trapping”, which I consider to be bogus and generally unhelpful.
The naming of the GHE, is I suggest, due to our inhabitting the surface. To illustrate this and my issue with “heat trapping”, I will pose the following question in an idealised atmosphere (see below for part of the idealisation).
In terms of just the atmospheric part, does the addition of GHGs move an atmospheric system as a whole towards a warmer or cooler state, or make no difference?
My preference, or prejudice, would be to say that it tends to cool an atmosphere as a whole but also redistribute energy towards the DALR profile. The notion of a GHE being solely a POV issue. For a denizen of the upper atmosphere it might be termed the IBE (Ice Box Effect). I like to put it this way for I find that everybody hates the notion. It seems clear to me that the effect of adding GHGs when viewed from an atmospheric system perspective is to produce a strong cooling tendency that is acted against by a strong response in the form of sensible and latent fluxes.
There is a level of idealisation going on here, Notably an absence of SW absorption and the production of warming in the stratosphere of our Earth. For those who can put that to one side, I think that there is an opportunity for insight into an origin for of the surface GHE in terms of an overall cooling tendency. The complication due the real stratospheric warming and the way that may contribute to the production of the tropopause and in the determination of its height puts the question of whether the real atmosphere as a whole would actually warm, cool, or stay the same into some doubt. That is by the bye in terms of the idealisation I have assumed.
I view the GHE and the IBE as two inseparable sides to the same coin. Compared to the non-GHG isothermal case where the whole system assumes the SB equillibrium temperature, the addition of GHGs causes the surface to be warmer (GHE) but crucially the upper troposhere (on the real Earth) to be cooler (IBE). If people must have “heat trapping” I say they must also have “heat releasing” but I would rather they simply dropped that metaphor altogether. GHGs couple the atmoshpere to the radiative field and whether a cooling or a warming takes place locally, is determined by the spectra of the GHGs, their local density, the local temperature and the local strength of the radiative field at each frequency.
I don’t expect anyone to agree with this, amongst skeptics it may be viewed as a AGW trojan horse, amongst the staunch AGW dogmatists it seems to be viewed as deeply unhelpful perhaps largely due to the loss of the “heat trapping” metaphor, or simply wrong. Hopefully it is a POV that people can have fun with and might just break down some barriers to thinking about GHGEs (Greenhouse gas effects).
It is not all about warming.
Alex
Willis,
please get back to me via email, not here – I just don’t have the time.
Put simply, ignoring the electrical input into the earth system will lead you down many, intellectually attractive, paths.
Have a look at plasma physics and its applicability to your topics – you might be more than surprised,
Louis
David says
The air moving up and down exchanges potential energy (PE) for kinetic energy (KE). The air moving down loses PE but gains KE, and vice versa for the air moving up.
——-
I have not entirely digested the article but an important consideration may be that Willis is referring to an atmosphere that is in equilibrium, without external energy sources. This means that there is NO motion of the air.
David you are referring to air in motion. Which means there must be an external energy source to keep the air in motion.
So David and Willis are describing different situations.
An inverted cone 1klm in DIA, 5klm high, 10m DIA at top, on stilts above water, so atmosphere can enter down low.
Intoduce Co2 @ur momisugly 5,000ppm with a Co2 drip feed relative to the life of atmospheric Co2. Headed by a turbine.
Just like GH theory, the Co2 enriched atmosphere inside must warm more than the atmosphere coming in below, and because of thermodynamics the heat at the top will turn that turbine.
I’m looking at the problem from a different direction. That of stability. Think of a column of air running from the ground to space. The temperature of this column of air at the very top is fixed. It is the temperature of space itself. As you descend through this column of air, the rate at which the air warms is determined by the lapse rate. Anytime a particular patch of air gets above the temperature determined by the lapse rate for that depth, it immediately becomes more boyant than the surrounding air and starts rising. It cools, but it still remains above the temperature of the air in it’s new surroundings. It rises until it reaches the top of the column, where it radiates it’s excess heat out into space.
This is not a perpetual motion machine, because it isn’t gravity that is causing the heating. It’s the sun. Take away the sun and quickly the whole column of air freezes. Increasing or decreasing the amount of energy coming from the sun will increase or decrease the total energy in the column of air, but the result of this is and expansion or contraction of the air, causing the column to grow or shrink. When the column expands, the average density of the air changes, which decreases the lapse rate. However the temperature at the top of the column and the bottom of the column remain the same. Decrease the energy from the sun, and the density of the air increases, and the height of the column decreases, but the temperature at the top and bottom still remain the same.
This relationship stays true until air cools to the point that it becomes a liquid.
The basic assumption of the radiation theory is that as mass gains energy when it enters a gravity field, all that energy will eventually be radiated away to space as EM radiation. This could take some time but for a gas it wouldn’t be that long.
All the thermal energy gained from gravitational potential energy is then eventually radiated away to space as EM radiation (give or take some cosmic background radiation re-entering the system).
Therefore: Gravitational Potential Energy = EM Energy
Therefore: the gravitational energy will eventually be radiated away to space – for gasses this should be relatively fast.
Well, that now gives us the theory of everything.
Except gravitational energy is not observed to decrease/radiate away over time unless the mass declines so the basic assumption is not complete. Thermal energy radiates away, but gravity does not.
That then implies:
– when an object which has gained energy in a gravity field loses EM energy through EM radiation, it must gain that back from the gravity field; or,
– gravitational energy is only interchangeble with EM/thermal energy at a limited level. It must be so small that we cannot detect a decline in gravity. Higgs bosons do not directly turn into EM photons, or only rarely; or,
– whatever gravitational energy that is not converted into EM energy remains in the system and is what we perceive as gravity.
There are all kinds of issues with this picture that are not understood at all.
Birdieshooter says:
January 20, 2012 at 2:30 am
My reply to all the questions raised above on both sides is WWES…….What Would Einstein Say? I would genuinely like to know. I wonder if he would have enjoyed these blogs. Anyone channel him lately?
He would say:
“If Jeremy and Willis are right, there goes relativity!”