Over at Watts Up With That, there was a discussion about the greenhouse effect which focused on a thought experiment of the temperature of a planet with an atmosphere devoid of IR radiating, so-called “greenhouse gasses”. I suddenly realized that there was something terribly wrong about the whole hypothesized mechanism.
A spherically distributed atmosphere cannot exist without a thermal gradient. In a steady state condition, the temperature profile must have a Laplacian of zero. And, as we all know here, setting the Laplacian to zero gives you a 1/r style result just like it does for the gravitational potential. What that means is that, there is always a temperature gradient, and heat must continually flow into the atmosphere from the conducting interface with the surface. And, that heat must build, and build, and build until it finds an outlet. One such outlet is IR radiation from… “greenhouse gasses”.
“Greenhouse gasses” do not heat the surface. They prevent it from heating continuously until emissions beyond the IR are stimulated, or until the atmosphere boils off, whichever comes first, by providing a radiative heat sink for the atmosphere.
In the steady state, the result is exactly the same as the standard greenhouse effect, with radiation from the surface balancing with the IR gas radiation so that incoming flux = outgoing flux. But, the mechanism is diametrically opposed. Yet, the cooling hypothesis must be the correct interpretation, because heat must continually flow into the atmosphere.
This hypothesis also solves another conundrum: if the atmosphere-less Earth would be at -18C without an atmosphere, and the major greenhouse gas is water vapor, then how did the water un-freeze to heat the Earth?
I go over all the points in my posts at the link. A good place to start is here.
Oh, you’re the same Bart as WUWT’s Bart. ^_^
I’d posted here in the first thread you linked. I argued that I could flip Willis’s column of air over with no input of work, returning it to the adiabatic lapse rate, and since there wasn’t an input of work I could do it all day long.
I was tempted to claim that since I input absolutely no work, I found a job flipping such equilibrium air columns upside-down all across the universe with nothing but the power of my mind, driving countless advanced species crazy when their air columns fail to reach thermal equilibrium. They curse me as Maxwell’s Demon.
I’m not dead sure if I’m right or not, but it does suggest another thought experiment. If the dry adiabatic lapse rate is the thermal equilibrium in a gravitational field (and how could it be possible for me to move a giant air column so far away from thermal equilibrium without a massive input of work?) then it should be impossible for us to devise a heat engine that would run from the temperature difference created by the adiabatic lapse rate. It should therefore be possible to devise a heat engine that would run from the energy difference in a tall column of air at thermal equilibrium in a gravitational field, perhaps by moving a parcel of air downwards (thus compressing and heating it), and using the delta T between that parcel and the air surrounding it which would still be at the parcel’s original and much lower temperature. Conversely, the column of air that rises (being displaced) has its temperature drop below the column’s equilibrium temperature, creating another delta T that could drive a heat engine. Since a heat engine can’t run from a system that’s in thermal equilibrium, I conclude that a column of gas in a gravitational field has an equilibrium at the adiabatic lapse rate, not at a constant temperature.
Thoughts?
My thoughts? I need to chew on that a little. I am certain that a column of gas in a gravitational field cannot be at equilibrium with constant temperature.
However, an adiabatic lapse rate requires a heat sink, provided by gases radiating heat away. I think my contribution here shows that without that, temperatures will continue climbing until the heat finds a way out, either by radiation at higher energy, or boiling away of the atmosphere.
I think a good electrical analogy is a capacitor hooked up to a constant current source. If you don’t short it with a resistor in parallel… kablooie!
I had a few more replies to Willis. The crux of his thought experiment seems to be connecting a thermo-couple to the top and bottom of an atmosphere that’s at the adiabatic lapse rate and extracting heat.
Given that the adiabatic lapse rate here is about 2C per 1000 feet, I think even silver could only conduct about 2.4 Watts per square meter, and that’s if there isn’t some similar adiabatic phenomenon in real-world solids under immense pressure, along with the motion of the solid’s atoms having to fight the gravity well all the way up.
“Greenhouse gasses” do not heat the surface. They prevent it from heating continuously until emissions beyond the IR are stimulated, or until the atmosphere boils off, whichever comes first, by providing a radiative heat sink for the atmosphere.
I think you misunderstand features of this particular model of pure radiative heat flow in a planetary atmosphere with a spherically hot sun and cold deep space (that is, there is an attenuated high frequency light from space so effective temperature of deep space is much lower than the spectrum would suggest). First, the atmosphere does not heat anything. It intercepts radiation from higher or lower in the atmospheric column and from the surface and outside the atmosphere. Radiative cooling is the mechanism by which the surface is kept from getting infinitely hot not the atmosphere or some component of it. An atmosphere can help by reducing the solar radiation coming in (that is, keeping heat out) or hinder it by reducing the radiation coming away from the surface
Greenhouse gasses intercept particular frequency radiation from lower in the atmospheric column or surface to deep space. They are as a result a less effective radiative heat sink than deep space. But they’re also transparent to most of the solar radiation going in. So the model is that heating of the lower atmosphere occurs with higher concentrations of green house gasses because more heat is trapped for longer times in Earth’s atmosphere.
In the linked thought experiment, if one had a planet with an atmosphere that is perfectly transparent to radiation and one then adds on the effects of heat conduction to that atmosphere, then the surface is actually cooled by the presence of the atmosphere which has the effective property of increasing the surface area of the planet to some degree.
“…then the surface is actually cooled by the presence of the atmosphere which has the effective property of increasing the surface area of the planet to some degree.”
It conducts heat away from that surface. But, it can’t radiate, and it can’t absorb, it is completely transparent, so it doesn’t have an effect on surface area, effective or otherwise.
There are two ways of looking at the problem:
1) You can claim that the atmosphere will continually conduct heat away only until everything is at equilibrium, so that the surface is at the temperature set by the Stefan Boltzmann formula such that incoming and outgoing radiation balance. At this point, the atmosphere is at constant temperature throughout, so there are no more heat flows to disrupt the radiative equilibrium.
The problem with this point of view is that it is a circular argument. It iassumes a priori that equilibrium will be established, therefore the Stefan Boltzmann relationship will hold.
2) Another, equally plausible, scenario is that the system is unstable, such that equilibrium is never attained, even asymptotically. Then, the Stefan Boltzmann relationship does not hold, and there is no limit to surface temperature.
The temperature profile of the atmosphere due to the surface/atmosphere conductance has to satisfy the heat equation. Solutions of the heat equation exist for both of these alternatives, as I have had to acknowledge in my lastest posting here. But, the runaway scenario #2 is more satisfying from a stability viewpoint. If scenario #1 is the case then, since water freezes at the non-atmospheric equilibirum temperature of the Earth, a question arises as to how the effect ever got started, and there remains a possibility of slipping back to that lower energy equilibrium state.
And, if you want to know the perils of dismissing the possibility of transition to a lower energy state from a quasi-stable higher energy state… Well, the denizens of this site know where to look.
I am sifting through the problem to try to find some requirement which will decide the question one way or the other. When I find it, I will let you know. Other inputs which would contribute to that search are welcome, but baseless assertions, based on the standard way most people think things should be, are not. As of right now, mostly what I have gotten are baseless assertions that SB must hold regardless of anything else going on, and that argument has no foundation.
Transparent objects can still radiate.
Also, come up with a math model that describes what you’re trying to say.
Equilibrium also is a reasonable assumption for a model that has constant boundary conditions and large scale stability (start with a really hot Earth or really cold Earth and that will move towards what I was thinking was a stable point) or simple models such as the radiative model you started with.
I believe I have found the solution. See what you think.
So, umm, has anyone considered just putting a price on removing carbon from the atmosphere and letting the market solve the problem? People who really think the world is going to end because of all the carbon in the atmosphere can pay for it.
Oh, right, people who believe in catastrophic climate change don’t believe in free markets. Never mind.
Any questions or criticisms anyone may have, have generally already been addressed at the link, so if anyone has an objection, I advise searching for whatever keywords describe it there.
The key thing is, any material body exposed to heat in a vacuum will start to increase in temperature until such a time as it can radiate as much out as is coming in. That holds for the atmosphere as well as the planet. So-called GHGs radiate in the low energy IR, and so they provide a low energy outlet so that temperatures can settle down to a reasonable level.
OK, so Ill admit that I quit reading after the sentence that included this phrase,
“…a quasi-judicial state body…”
there was no need to go on IMHO. It’s the same crap every time. Socialists or outright admitted Communists standing in the way of progress and jobs under the guise of protecting the environment. I’m not by nature a violent person, but if we don’t wind up with a collapse and a new revolution I’ll be greatly surprised.
And, while I’m b1tching, I wish someone would show me, in the U.S. Constitution or any State Constitutions, just WHERE there is the power to turn our rights over to a “quasi-judicial state body”.
Just got around to reading this; excellent artice.
Too many of those who believe that climate change is an emergency that must be dealt with by any means necessary see democracy itself as an obstacle to an effective response.
Well, here’s a good place to post this again.
Over at Watts Up With That, there was a discussion about the greenhouse effect which focused on a thought experiment of the temperature of a planet with an atmosphere devoid of IR radiating, so-called “greenhouse gasses”. I suddenly realized that there was something terribly wrong about the whole hypothesized mechanism.
A spherically distributed atmosphere cannot exist without a thermal gradient. In a steady state condition, the temperature profile must have a Laplacian of zero. And, as we all know here, setting the Laplacian to zero gives you a 1/r style result just like it does for the gravitational potential. What that means is that, there is always a temperature gradient, and heat must continually flow into the atmosphere from the conducting interface with the surface. And, that heat must build, and build, and build until it finds an outlet. One such outlet is IR radiation from… “greenhouse gasses”.
“Greenhouse gasses” do not heat the surface. They prevent it from heating continuously until emissions beyond the IR are stimulated, or until the atmosphere boils off, whichever comes first, by providing a radiative heat sink for the atmosphere.
In the steady state, the result is exactly the same as the standard greenhouse effect, with radiation from the surface balancing with the IR gas radiation so that incoming flux = outgoing flux. But, the mechanism is diametrically opposed. Yet, the cooling hypothesis must be the correct interpretation, because heat must continually flow into the atmosphere.
This hypothesis also solves another conundrum: if the atmosphere-less Earth would be at -18C without an atmosphere, and the major greenhouse gas is water vapor, then how did the water un-freeze to heat the Earth?
I go over all the points in my posts at the link. A good place to start is here.
Oh, you’re the same Bart as WUWT’s Bart. ^_^
I’d posted here in the first thread you linked. I argued that I could flip Willis’s column of air over with no input of work, returning it to the adiabatic lapse rate, and since there wasn’t an input of work I could do it all day long.
I was tempted to claim that since I input absolutely no work, I found a job flipping such equilibrium air columns upside-down all across the universe with nothing but the power of my mind, driving countless advanced species crazy when their air columns fail to reach thermal equilibrium. They curse me as Maxwell’s Demon.
I’m not dead sure if I’m right or not, but it does suggest another thought experiment. If the dry adiabatic lapse rate is the thermal equilibrium in a gravitational field (and how could it be possible for me to move a giant air column so far away from thermal equilibrium without a massive input of work?) then it should be impossible for us to devise a heat engine that would run from the temperature difference created by the adiabatic lapse rate. It should therefore be possible to devise a heat engine that would run from the energy difference in a tall column of air at thermal equilibrium in a gravitational field, perhaps by moving a parcel of air downwards (thus compressing and heating it), and using the delta T between that parcel and the air surrounding it which would still be at the parcel’s original and much lower temperature. Conversely, the column of air that rises (being displaced) has its temperature drop below the column’s equilibrium temperature, creating another delta T that could drive a heat engine. Since a heat engine can’t run from a system that’s in thermal equilibrium, I conclude that a column of gas in a gravitational field has an equilibrium at the adiabatic lapse rate, not at a constant temperature.
Thoughts?
My thoughts? I need to chew on that a little. I am certain that a column of gas in a gravitational field cannot be at equilibrium with constant temperature.
However, an adiabatic lapse rate requires a heat sink, provided by gases radiating heat away. I think my contribution here shows that without that, temperatures will continue climbing until the heat finds a way out, either by radiation at higher energy, or boiling away of the atmosphere.
I think a good electrical analogy is a capacitor hooked up to a constant current source. If you don’t short it with a resistor in parallel… kablooie!
I had a few more replies to Willis. The crux of his thought experiment seems to be connecting a thermo-couple to the top and bottom of an atmosphere that’s at the adiabatic lapse rate and extracting heat.
Given that the adiabatic lapse rate here is about 2C per 1000 feet, I think even silver could only conduct about 2.4 Watts per square meter, and that’s if there isn’t some similar adiabatic phenomenon in real-world solids under immense pressure, along with the motion of the solid’s atoms having to fight the gravity well all the way up.
“Greenhouse gasses” do not heat the surface. They prevent it from heating continuously until emissions beyond the IR are stimulated, or until the atmosphere boils off, whichever comes first, by providing a radiative heat sink for the atmosphere.
I think you misunderstand features of this particular model of pure radiative heat flow in a planetary atmosphere with a spherically hot sun and cold deep space (that is, there is an attenuated high frequency light from space so effective temperature of deep space is much lower than the spectrum would suggest). First, the atmosphere does not heat anything. It intercepts radiation from higher or lower in the atmospheric column and from the surface and outside the atmosphere. Radiative cooling is the mechanism by which the surface is kept from getting infinitely hot not the atmosphere or some component of it. An atmosphere can help by reducing the solar radiation coming in (that is, keeping heat out) or hinder it by reducing the radiation coming away from the surface
Greenhouse gasses intercept particular frequency radiation from lower in the atmospheric column or surface to deep space. They are as a result a less effective radiative heat sink than deep space. But they’re also transparent to most of the solar radiation going in. So the model is that heating of the lower atmosphere occurs with higher concentrations of green house gasses because more heat is trapped for longer times in Earth’s atmosphere.
In the linked thought experiment, if one had a planet with an atmosphere that is perfectly transparent to radiation and one then adds on the effects of heat conduction to that atmosphere, then the surface is actually cooled by the presence of the atmosphere which has the effective property of increasing the surface area of the planet to some degree.
“…then the surface is actually cooled by the presence of the atmosphere which has the effective property of increasing the surface area of the planet to some degree.”
It conducts heat away from that surface. But, it can’t radiate, and it can’t absorb, it is completely transparent, so it doesn’t have an effect on surface area, effective or otherwise.
There are two ways of looking at the problem:
1) You can claim that the atmosphere will continually conduct heat away only until everything is at equilibrium, so that the surface is at the temperature set by the Stefan Boltzmann formula such that incoming and outgoing radiation balance. At this point, the atmosphere is at constant temperature throughout, so there are no more heat flows to disrupt the radiative equilibrium.
The problem with this point of view is that it is a circular argument. It iassumes a priori that equilibrium will be established, therefore the Stefan Boltzmann relationship will hold.
2) Another, equally plausible, scenario is that the system is unstable, such that equilibrium is never attained, even asymptotically. Then, the Stefan Boltzmann relationship does not hold, and there is no limit to surface temperature.
The temperature profile of the atmosphere due to the surface/atmosphere conductance has to satisfy the heat equation. Solutions of the heat equation exist for both of these alternatives, as I have had to acknowledge in my lastest posting here. But, the runaway scenario #2 is more satisfying from a stability viewpoint. If scenario #1 is the case then, since water freezes at the non-atmospheric equilibirum temperature of the Earth, a question arises as to how the effect ever got started, and there remains a possibility of slipping back to that lower energy equilibrium state.
And, if you want to know the perils of dismissing the possibility of transition to a lower energy state from a quasi-stable higher energy state… Well, the denizens of this site know where to look.
I am sifting through the problem to try to find some requirement which will decide the question one way or the other. When I find it, I will let you know. Other inputs which would contribute to that search are welcome, but baseless assertions, based on the standard way most people think things should be, are not. As of right now, mostly what I have gotten are baseless assertions that SB must hold regardless of anything else going on, and that argument has no foundation.
Transparent objects can still radiate.
Also, come up with a math model that describes what you’re trying to say.
Equilibrium also is a reasonable assumption for a model that has constant boundary conditions and large scale stability (start with a really hot Earth or really cold Earth and that will move towards what I was thinking was a stable point) or simple models such as the radiative model you started with.
I believe I have found the solution. See what you think.
So, umm, has anyone considered just putting a price on removing carbon from the atmosphere and letting the market solve the problem? People who really think the world is going to end because of all the carbon in the atmosphere can pay for it.
Oh, right, people who believe in catastrophic climate change don’t believe in free markets. Never mind.
Any questions or criticisms anyone may have, have generally already been addressed at the link, so if anyone has an objection, I advise searching for whatever keywords describe it there.
The key thing is, any material body exposed to heat in a vacuum will start to increase in temperature until such a time as it can radiate as much out as is coming in. That holds for the atmosphere as well as the planet. So-called GHGs radiate in the low energy IR, and so they provide a low energy outlet so that temperatures can settle down to a reasonable level.
OK, so Ill admit that I quit reading after the sentence that included this phrase,
“…a quasi-judicial state body…”
there was no need to go on IMHO. It’s the same crap every time. Socialists or outright admitted Communists standing in the way of progress and jobs under the guise of protecting the environment. I’m not by nature a violent person, but if we don’t wind up with a collapse and a new revolution I’ll be greatly surprised.
And, while I’m b1tching, I wish someone would show me, in the U.S. Constitution or any State Constitutions, just WHERE there is the power to turn our rights over to a “quasi-judicial state body”.
Just got around to reading this; excellent artice.
Too many of those who believe that climate change is an emergency that must be dealt with by any means necessary see democracy itself as an obstacle to an effective response.
Bing.