"Heat generally cannot spontaneously flow [i.e. the net vector] from a material at lower temperature to a material at higher temperature."or
“Heat doesn’t flow from cold to hot (without work input)”Note how this diagram from NASA of the second law of thermodynamics (without work input) illustrates the net flow of heat as a one-way vector always from hot to cold:
Work input is required to cause any heat to flow from cold to hot, which is obviously true from everyday experience. For example in a refrigerator, heat flows from cold to hot, but only when aided by an external agent (i.e. the compressor). Note that from the mathematical definition of entropy, a process in which heat flows from cold to hot has decreasing entropy. This can happen in a non-isolated system if entropy is created elsewhere, such that the total entropy is constant or increasing, as required by the second law. For example, the electrical energy going into a refrigerator is converted to heat and goes out the back, representing a net increase in entropy.
Another way of stating the Clausius formulation of relevance to the AGW debate is
"energy from the hotter body has left that body - it therefore cools down. The smaller amount of energy from the cooler body cannot fully replace that lost energy; it just slows the rate of cooling."Since "greenhouse" gases cannot add any energy to the system, or "work input", and are colder than the surface of the earth, they cannot cause additional warming of the earth; they just slow the rate of cooling. Furthermore, the "sunshade" or cooling effect of "greenhouse" gases outweighs the heating effect (due to absorption of incoming solar energy) by a factor of 100.
UPDATE: Alan Siddons (who is not the author of the above post) has just forwarded his reply to those questioning violation of the 2nd law of thermodynamics:
Key statement: The notion that colder matter does not radiate towards hotter matter defies common sense and causality.
I always see that weasel word: Toward. No doubt a cooler object does radiate "toward" a warmer object. The question is what happens as a result.
Say you have a blackbody plate (think of an electric heater) radiating 1000 W/m² toward another plate which, because of distance, absorbs half of that intensity, i.e., 500 W/m². At equilibrium, the receiving plate thus radiates 250 W/m² toward the 1000 W/m² plate. Question: Does the 1000 W/m² plate thereby rise to 1250 W/m²? If so, then, by raising the radiator’s temperature without adding more energy, you’ve disproved the first law of thermodynamics. Effectively, you’ve made the radiator heat itself. Moreover, now at 1250 W/m², the radiator will heat the other plate still more, absorb another dose of back-radiated energy, and will reach 1562 W/m². And so on, ad infinitum.
Either radiative heat transfer obeys the 2nd Law or it does not. If the 2nd Law does hold, then light can only transfer energy to something that is radiating less. This would mean that the physics of radiative forcing is fictitious.
".. they just slow the rate of cooling"ReplyDelete
That is the point of how greenhouse gases work!
If the Earth's surface was in thermal equilibrium with the sun then it would be 6000K. As the Earth is not that warm the sun's rays warm the Earth during the day. Luckily space is very cold, about 3K so the Earth quickly loses this heat to space.
Greenhouse gases slow the cooling so that the Earth is warmer than it would be, but obviously not warmer than the sun. Is it so hard to understand? It is akin to putting on a warm jacket. The jacket does not create any energy but slows the rate your body loses heat to the environment.
No, it's not hard to understand. You seem to have missed the point - "greenhouse" gases slow the rate of cooling but they do not cause warming of the earth since they cannot add work input.ReplyDelete
Except that there is a source of energy coming in to the earth, and the greenhouse effect is slowing the rate at which that energy departs the earth.Delete
If I have a pond full of water (the sun) and I allow some of the water to flow down into another pond (the earth), that pond will fill up. It will continue to fill until it reaches a level where the amount that can spill out over the rim is equal to the amount flowing in from the higher pond. This is the steady state.
If I then go into the outflow of the lower pond, and block it up a little (the greenhouse effect), the amount of water that can flow out at this level is decreased. So the water level will rise again, until it can once again flow out at the same rate it did before. The blockage in the drain does not add any water to the system, but it does prevent the lower pond from losing energy as water as easily as it did before, and will trap more water in the system.
I withdraw my comment from 7/2/10. I actuality, increased water vapor cools the planet due to a decreased lapse rateDelete
whether one considers electromagnetic radiation as a wave or particle, a lower energy/frequency/temperature body cannot increase the temperature of a higher energy/frequency/temperature body. Waves or particles are bidirectional between the hot & cold bodies, but HEAT FLOW is always unidirectional from hot to cold. The incorrect notion of bidirectional heat flow is the source of the fallacious “back-radiation radiative forcing” greenhouse theory. The real 33K greenhouse effect is due to atmospheric mass/gravity/adiabatic compression, not “radiative forcing” from greenhouse gases.
The 2nd law of thermodynamics on a quantum scale:
why a colder body absolutely cannot increase the temperature of a warmer body. Radiation from a lower energy/frequency/temperature body cannot raise the energy/frequency/temperature of a warmer body.
If you wish to consider light as a wave phenomenon, a lower frequency wave from a colder body produces destructive interference with a higher frequency/energy/temperature wave of a warmer body, thus cannot increase the frequency/amplitude/energy/temperature of the warmer body.
If you wish to consider light as a quantum/photon phenomenon, a lower energy photon from a colder body cannot increase the energy of a higher energy/temperature body because all of the lower energy quantum states in the higher energy/warmer body are already filled. A lower energy photon cannot raise a quantum state above its own energy level, thus has no effect on the quantum state/energy/temperature of the higher energy/temperature body.
There is no “net” two way flow of heat for the above reasons; it’s one-way only, even though photons or waves are indeed bi-directional. Heat flows one way only, from hot to cold, and the -18C atmosphere cannot warm the 15C surface.
Gravity, atmospheric mass, adiabatic compression, however, do heat the atmosphere and surface ~33K as Steven Wilde, Nikolov & Zeller, and many others have shown.
A(n effective) blackbody radiates with a particular spectral shape with a peak following Wien's displacement law. The position of that peak shifts slowly with temperature, but the peak position move in wavelength is fairly slow, so that two blackbodies 20 degrees apart do not have a significant shift in their spectral profile.Delete
Let's say you have a body at some temperature T. Then you put two blackbodies next to it, one at T-10K and one at T+10K. According to the above posts, the lower temperature body cannot affect the higher one by radiation at all. So there should be no radiative impact of the lower temperature blackbody, but there should be from the higher one (at least, it is not forbidden, according to the above statements). However, the two blackbodies have effectively identical emission spectra. How does the receiving body know which photons are coming from the blackbody that is at a lower temperature and one that is higher? Something is amiss.
The answer, I think, is that the 2nd law describes (as a lot of thermodynamic laws do) the statistical aggregate (or net) flow. In particular, the explanation in the third-to-last paragraph above conflates quantum states of a single body with temperature. Definition of temperature is another aggregate property that is extremely difficult to define for a single particle. But one thing is for sure from thermodynamics: just because a body is at a given temperature, does not mean that every "energy state," however you choose to define it for an ensemble, is filled. There would not be an energy distribution associated with it otherwise.
As for the explanation that radiation from a lower-temperature body produces destructive interference with the higher frequency wave of a warmer body, and thus cannot affect the warmer body, I do not quite know the mechanism that is being described. But I do know that no complete destructive interference can occur between waves of different frequencies. That would require the waves to be of exactly the same frequency. Otherwise, you get sum and difference (or beat) frequencies associated with such superposition, even if there were a physical process by which this would take place (which is unlikely, since there would be no phase cohesion between the waves as described).
I think the main point of contention in the "radiation cannot warm the Earth" argument is in wording: I do not think anyone says the atmosphere warms the Earth. The external source of energy is doing that. But this effect causes the Earth to get less cool than it otherwise might, as it continues to receive the external, causing an increase in average effective temperature. This deals only with the radiation that makes it to the ground, so any argument about sunshading or absorbed radiation is not applicable.
No read the reply 5/21/14 once again.Delete
Radiation is bidirectional, but heat flow is always unidirectional.
This is true whether one considers light as a quantum/photon or a wave phenomenon. It's called the frequency cutoff for thermalization. A lower frequency/energy/temperature body cannot increase the energy levels in a higher frequency/energy/temperature body since the lower frequency levels are already completely filled.
"I do not think anyone says the atmosphere warms the Earth."
Uh, yes they do by 33C warmer. Less COOLING is still COOLING, not WARMING.
I did read the reply of 5/21/14, and none of it answers my previous post. I am not even sure what you mean by a lower frequency/energy/temperature body, since those terms are not necessarily related. As I mentioned, temperature is an ensemble property, and is ill-defined for a single particle, but an ensemble does not have well defined energy levels, since those are properties of a single quantum state (which an ensemble is not, unless it is somehow in a quantum coherent state, which would easily fall apart. Basically, temperature is a classical property, energy states are a quantum property; which is backed up by the example of the T+t and T-t blackbodies radiating at the same third body at T. Even though one has a higher temperature and one a lower temperature, their radiation spectra are nearly identical. The body at T has no way of distinguishing the photons from one from the photons of the other, thus rejecting one and accepting the other. Yet, by the statements you made above, the T-t temperature body should not impart any absorbed radiation to the T body, while the T+t body should. That does not make sense...because the definition of temperature and energy levels apply to different schemes, and having a higher temperature for a system does not mean that every single quantum state in that system is filled (because every ensemble has an energy distribution among its particles).Delete
If something cools less than it should, then it is warmer than it should be. That Earth is never going to be as warm as it would be if it absorbed all the impinging Solar radiation, because it will re-emit a lot of it. But if it receives back some of the radiation that otherwise would have been re-emitted, then it will not become as cool as it should be. Hence, it will be warmer than it should be. Hence, warming. This is because it continues to receive the impinging Solar radiation at the same time that it gets back more than it should from the atmosphere. If the Sun did not continue to input energy into this system, then the picture put forth here would be correct.
Perhaps the most direct way to say it, following the radiator example above, is this:Delete
If the radiator at 1000 W/m^2 is radiating, and yet remains at 1000 W/m^2, then it has to be driven by some other generator outside of this consideration. If the radiator started at 1000 W/m^2, and then the other plate started at zero, and this system was left to go, the radiator would get cooler and the initially cool block would get warmer (just a heated block removed from its source and placed in contact with a cooler block will cool down). But, by the reasoning stated above, the radiator is still at 1000 W/m^2 when it receives the return from the cooler piece. This means it must be getting its energy continuously from somewhere else (a heating element), making it a driven system.
To properly apply the second law, you need to consider an entire closed system (with no overall input or output). Otherwise, we could, for example, say that someone putting things away in a room violates the 2nd law, because, considering only the person and the solid objects in the room, things end up in a more ordered state. But this does not consider what is done to the air in the room. Even if the person could direct the heat he or she generates out of the room, it would go into the wider world. Overall, the 2nd law remains unviolated, but only because you have to consider a closed system.
Here, the ground and atmosphere do not constitute a closed system, since they are receiving significant energy input from Solar radiation. So a second (or a first) law argument applied to just those two elements is invalid.
"So a second (or a first) law argument applied to just those two elements is invalid."Delete
False, the 2nd law applies to open systems, closed systems, the Earth, atmosphere, and universe.
The radiator example proves nothing. Heat flows from hot to cold only one-way period. If something else is heating the radiator at 1000 W/m2, that source must be hotter than 1000 W/m2.
"If something cools less than it should, then it is warmer than it should be."Delete
False semantics. If something COOLS then it is COOLER, not warmer. Slowing COOLING does not make a body warmer.
The GHE falsely postulates slowing the COOLING of a body at 255K makes it 33K WARMER. Absolutely false. A body COOLING at 255K will be at a temperature of 255K or less, never more than 255K.
"I am not even sure what you mean by a lower frequency/energy/temperature body, since those terms are not necessarily related."
Of course they are related:
1. Wavelength and temperature are related by Wien's displacement law
2. Wavelength and frequency are inversely related by wavelength = [speed of light]/frequency
3. Wavelength or frequency is related to temperature & energy by Planck's Law
Thus, frequency/energy/temperature are directly related by fundamental thermodynamics.
A lower frequency/energy/temperature body absolutely cannot warm a higher frequency/energy/temperature body due to both the 1st and 2nd laws of thermodynamics.
This concludes our conversation on this old thread. I don't have the time to tutor you on the basic physics that have already been explained several times in this post and in the comments. Bye
This comment has been removed by the author.Delete
Comment from Alan Siddons: If a cool body can heat a warm body by radiation, the interchange will proceed infinitely and there is no upper limit on the temperature of either body. But the dispute proceeds because there is no way to defend Greenhouse Physics (radiative forcing) WITHOUT asserting that radiative heat transfer is exempt from the 2nd Law. Adherents WANT it to be so, and so they argue.ReplyDelete
But here's what professor M. Quinn Brewster has to say:
Thermal Radiative Transfer and Properties
Thermal radiation is electromagnetic radiation emitted by particles of matter (molecules, atoms, ions, and electrons) as they undergo internal energy state transitions. The radiative energy produced by these transitions is usually in the ultraviolet, visible, and infrared portions of the electromagnetic spectrum. Like all forms of electromagnetic radiation, thermal radiation travels at the speed of light.
Thermal radiation is also a form of heat. Heat, defined as thermal energy transfer from one body of matter to another due to a temperature difference, appears in two fundamental forms: conduction and radiation. The fundamental mechanism of energy transport in conduction is direct exchange of kinetic energy between particles of matter. In radiation, the fundamental mechanism of energy transport is by electromagnetic waves (or photons) that are emitted and absorbed by the particles of matter as they undergo energy state transitions.
Like conduction, thermal energy is in harmony with the second law of thermodynamics such that, in the absence of work, thermal energy is radiated spontaneously from higher temperature to lower temperature matter. Unlike conduction, however, which requires a material path, radiative transfer can occur between two spatially remote bodies of matter at different temperatures even when the intervening space is a vacuum. The most prominent example of thermal radiation on the earth is solar radiation, which is transported across the vacuum of space to the earth.
Translation: The second law of thermodynamics states that the transfer of thermal energy flows one way, from a zone of greater thermal energy to one of lesser energy. Not in the other direction. Conductive transfer and radiative transfer have this in common, and a cooler body cannot heat a warmer body by either method.
You are working from a fundamental misunderstanding of the second law of thermodynamics. It does not prevent energy from moving from a colder body to a hotter, it simply requires that the net transfer of energy is from hot to cold.Delete
If you put a hot object in an empty space, it radiates a certain amount of energy. If you put a cold object in, it radiates a lesser amount. The cold object absorbs the radiation that reaches it from the hot object, and the hot object absorbs the energy from cold. Since there is more of the former, however, the net exchange is hot to cold.
If you raise the temperature of the cold object a few degrees, it radiates that much more energy. It's still less than the hotter object, and the net flow is still hot to cold, but it is slightly slower than it was. Given that the input to the planet is (relatively) constant, this slowing results in a higher temperature, just like putting another blanket on the bed results in a warmer bed, despite the fact no additional energy is added.
A simple experiment to demonstrate the point:ReplyDelete
1. Shaded desk lamp on
2. White paper illuminated by the desk lamp
3. Mirror situated so that it reflects the light from the paper and not from the desk lamp back to the paper
4. If radiative forcing is correct, you should be able to see a brighter spot on the paper resulting from the reflection from the mirror
5. None is seen therefor hypothesis 4 is falsified
I think there are several flaws with this setup, starting with how the energy is returned to the paper. This assumes the reradiation will be in the visible, for one.Delete
that is not a "flaw of the setup"Delete
the mirror reflects the entire spectrum, including the visible spectrum back to the paper
The observer will not see any brightening of the visible spectrum on the paper
ie. 5. None is seen therefore hypothesis 4 is falsified
Except that the absorption and re-emission this is trying to compare to is not a simple reflective process. It is a Raman scattering process, which means that energy that comes in in one band may be emitted in another. Simply looking for a brighter spot is an incomplete assessment of the returned radiation.Delete
More radiation is returned by a mirror than by a Raman scattering process, therefore the example in this post provides an even better illustration of the GHE fallacy.Delete
In addition, LWIR scattered in the atmosphere is of lower frequency/energy than the solar shortwave heating the surface, therefore cannot heat the surface at all much less the claimed 33C
I fully agree that you cannot create 'order' without adding work. I also agree that the daft greenhouse gas 'forcing' theory cannot CREATE heat, but I think your explanations are somewhat confusing.ReplyDelete
You say that "heat doesn't flow from cold to hot" but I believe this statement confuses 'heat' and 'radiation'.
Surely the hot body emits MORE radiation because it is hotter. The cold body emits LESS radiation because it is colder. Radiation (ie energy) therefore is exchanged both ways but there is a NET movement of energy - and hence heat - from hot to cold as the hot body emits more, until they balance.
Suggesting energy only goes one way, rather than more one way and less the other, would require the bodies to be aware and know whether their neighbour was hotter or colder than they were and decide whether they should emit radiation or not!
The 2nd law definitely states heat only flows in one direction (without work input). Here's a simple example: It is common experience that a cup of hot coffee left in a cooler room eventually cools off. This process satisfies the first law of thermodynamics since the amount of energy lost by the coffee is equal to the amount gained by the surrounding air. Now let us consider the reverse process - the hot coffee getting even hotter in a cooler room as a result of heat transfer from the room air. We all know this process never takes place. It is clear that processes proceed in a certain direction and not in the reverse direction. The first law states that energy must be conserved and the second law tells you in which direction the process will occur.ReplyDelete
Here's some lecture slides with more detail:
and just google second law clausius for many more
Try the experiment suggested immediately above your post. Report back on your results.
Then try to explain what you see in terms of your notion of how radiated energy works.
Here's the unphysical IPCC concept of the greenhouse effect in a nutshell:ReplyDelete
1. A warm body (earth) radiates heat to a cool body (the atmosphere)
2. The cool body "back-radiates" (unphysical IPCC-speak) heat to the warm body.
3. This process repeats perpetually to create a perpetual heat engine with the net result that the warm body becomes warmer.
This is a blatant violation of the 2nd law.
While both cold and hot bodies radiate, the net heat flow must always be from hot to cold (without work input), regardless of the wavelength of the radiation.
You know it and I know it but does Woody43 know that the laws of thermodynamics pertain to energy transfer/transformation and not just to heat? In fact, does he know what heat actually is? Is it any more to him than just this feels hot, this feels cold, and this feels sort of in between?
To observe the greenhouse effect:ReplyDelete
Two days with similar temperature - one day has a clear night, the next has clouds move in in the evening. The cloudy night is warmer.
The amount of radiation leaving the Earth would be similar on both nights but the greatly increased water vapor in the clouds reduces the cooling. How does this happen if not through "back radiation"?
Alan, as stated in the post, "greenhouse" gases reduce the rate of cooling, but they do not cause warming since they cannot add work input. No unphysical back-radiation concept is necessary to explain this.ReplyDelete
But we do have an outside source of heat, the sun. And terrestrial radioactive decay, and gravitational decay.Delete
If the same amount of energy is coming in, but less is leaving (which is what "reducing the rate of cooling" means), what do you think happens to difference?
The Earth radiates exactly the same energy it receives from the Sun. Greenhouse theory also violates the 1st law of thermodynamics.Delete
Earth's "greenhouse" is due to adiabatic compression from atmospheric mass/gravity
Comment from Alan Siddons:ReplyDelete
Radiant transfer, "net flow," and the 2nd Law
In radiation, heat flows from a higher temperature body to a lower temperature body when the bodies are separated in space. (Kreith, Frank, Principles of Heat Transfer, 2nd Edition, University of Colorado)
Notice. There is nothing in this proposition which allows radiative heat flow from a lower temperature to a higher temperature body, meaning there is no allowance for any "interaction" between the two. It’s not a matter of a cooler body sending LESS energy to a warmer body, then, it’s a matter of not sending any energy at all. While cooling down, a warm object will simply heat a cooler one till transference cannot proceed because both are now the same.
The concept of a "net flow" of heat is useful for calculating that final condition but it doesn’t describe the physical reality. Radiative heat transfer conforms to the same principle as conductive heat transfer, of greater thermal energy seeping into less. The second law comprises both, and the second law doesn’t walk backwards.
The same laws that govern the transfer of light also govern the transfer of heat. (Christie Geankopolis, Transport Processes and Unit Operations, 3rd Edition, University of Minnesota)
Light can only illuminate something that is emitting less light; this is what governs the transfer of heat. Otherwise an emitter and a receiver will "interact" indefinitely and an endless mutual heating cascade will ensue -- even though the "net flow" is always from the hotter to the colder body.
What is going on in physics? Have LAWYERS taken over? How can anyone read in a textbook that "Heat is energy transferred as the result of a temperature difference" and somehow conclude that two bodies at different temperatures thereby exchange heat, so that heat flows two ways, both downhill and uphill? How can anyone read "When a temperature difference exists, the second law dictates that energy will flow naturally from the hotter body to the colder body" and simply choose to IGNORE this, proposing a back and forth flow of heat instead?
Exactly like conductive transfer, radiative transfer is a TRANSFER; it is not an exchange. "Net flow" is a convenient mathematical construct; it is not a reality.
You are describing why radiative forcing cannot exist. This is a way to subtle argument for AGW believers. Their significant others have told them it exists so they believe it MUST exist *somehow*. This is why I offered such an absurdly simple experiment that demonstrates the point.
It is an experiment base upon visible light radiation. A paper surface that reflects the bulk of the light hitting it and a mirror that reflects an even higher fraction of the light hitting it. All with a much greater efficiency than greenhouse gasses and the earth.
Further, ones eye is the sensor. We don't need thermometers, fancy IR spectrometers, lasers, or any such contrivance. The experiment can easily be performed by a rather average grade school student making average grades in science.
The results of the experiment completely and unambiguously falsifies the radiative forcing hypotheses. You do not see the light that comes from the paper and reflected by the mirror back to the paper brightening the paper. Thus no forcing. There never has been nor never will be. QED
There are no esoteric laws, no complicated maths, no high tech devices. Just everyday things that when properly arranged to optimize the possibility of radiative forcing, it is shown not to exist.
This should be the end of it but I fear not. We have too many minds locked onto a total myth and who fear to see what is in front of them. For to do so, they would have to deny their very identity and become their most hated enemy: a denier. They would no longer *belong*.
From an email from geophysicist Norm Kalmanovitch:ReplyDelete
My definition of the greenhouse effect is that it is just a number; 34.5°C for the Earth, 5.5°C for Mars and 450°C for Venus and is merely the theoretical difference in temperature between the actual temperature of a planet and what that temperature would be if there was no atmosphere.
It has nothing to do with what components cause what portion of this effect it is just the numerical value.
Most importantly the greenhouse effect has nothing to do with climate because climate is always changing and the greenhouse effect is essentially static.
The effect is caused by atmospheric components slowing down the rate at which thermal energy escapes from the planet during hours of darkness so it is essentially a passive insulating effect supplying no energy and therefore since climate requires energy, there is no driving of climate from this insulating effect.
All of the misleading terminology pertaining to the greenhouse effect was coined after the 1988 Hansen paper and the formation of the IPCC. There was no such term as greenhouse gas prior to 1988, and if there had been such a term defining the most prominent contributors to the Earth's greenhouse effect, it would not be GHG but GHP for greenhouse particles which are the water particles of clouds the provide well over 70% of the greenhouse effect. If there was a second term to define only the gaseous contributors to the greenhouse effect only three gases would be named water vapour, CO2, and ozone because these three gases account for most of the gaseous part of the greenhouse effect.
The next set of contributors would be N2 and O2, because these two gases make up 99% of the dry atmosphere and even though they have only a minor effect because of their molecular structure the effect from these two gases is still greater than any of the other gases named in the Kyoto Protocol and that includes methane because methane occupies a very narrow band in a low energy portion of the Earth's radiative spectrum that is already saturated by water vapour. Most of the other gases named in the Kyoto Protocol are completely outside the thermal spectrum radiated by the Earth. They are only included because they are pollutants and when included in the collective term GHG this makes GHG's pollutants and CO2 is depicted as a GHG so it can be named as a pollutant.
The greenhouse effect is real; the IPCC version of the greenhouse effect is just as make believe as the energy that the IPCC claims CO2 emissions create.
Yes, the experiment you described is the same one shown by Alan Siddons here in the post "Why conventional greenhouse theory violates the 1st law of thermodynamics" and does falsify the radiative forcing hypothesis as you have noted.
Yes, the two experiments will have the same qualitative result: radiative forcing is falsified. The point is that the experiment I propose uses ordinary things most computer users will have. The results can be seen using unaided eyesight without the aid of complex and expensive equipment. The experience can be direct and immediate.
There are a quite a few scientific principles that can be demonstrated by simple experiments using common materials.
There was no need for the $70 billion to have been spent on "climate change" research except for the lack of doing this simple experiment that costs but a few minutes of effort. There is even less need for the destruction of modern technological civilization and the enslavement of the population of the earth just to limit atmospheric CO2.
I have been struggling for weeks with questions similar to what I’ve just found on this page. One minute I think I’ve got it. The next minute it’s slipped through my fingers …ReplyDelete
I think I understand what is going on in the example proposed by Alan Siddons. Everything happens essentially instantaneously – really at the speed of light of course – but imagine first switching the radiator on to see some order in the events. Initially, 1000 units of energy leave the radiator. The black body is some distance away and only 500 units reach it. The other 500 units which came from the radiator end up in the surroundings. The black body immediately emits the same amount of energy as it receives, so it emits the 500 units. Again because of the separation distance, only half of this returns to the radiator, the other half going into the surroundings.
The radiator lost 1000 units and got 250 back an instant of time later. The net energy flowing out from the radiator is 1000 – 250 = 750 units. The surroundings got 500 units from the radiator and 250 units from the black body for a total of 750 units. Energy is conserved. All the photons which started out from the radiator and made up that 1000 units of energy are accounted for. This explains one circuit but the same thing is going on continually over and over again until the radiator is switched off.
Now change the rules and say that the radiator is also a black body, if that is possible. (A black body is not supposed to have any internal structure, is it? But here we have to assume that the radiator somehow can generate energy as before.) This time, the 250 units which came back to it are immediately emitted again. What happened to the initial 1000 units is now repeated for the 250 units re-emitted from the radiator.
In the first round, 1000 units leave the radiator, R. The black body, B, receive 500 units and the surroundings receive 500 units.
In round 2, B emits 500 units. R gets 250 of them and S gets 250 of them too.
In the third round, R emits 250 units and 125 end up in both B and S.
In the fourth round B emits 125 units and R and S both receive 62.5 units.
The pattern is clear. The radiator suffers a net loss of exactly 1000 units and the surroundings receive 500 + 250 + 125 + 62.5 + … , with each new term in the series being half of the current one. The sum of this geometric series is 1000. Therefore all the energy which leaves the radiator eventually goes to the surroundings, exactly as before.
"Heat generally cannot spontaneously flow [i.e. the net vector] from a material at lower temperature to a material at higher temperature."ReplyDelete
The NET VECTOR - the difference between the radiative fluxes emitted by the two bodies. There's general confusion here about what this means. BOTH bodies emit radiation. In the example above, the net flux is 1000 - 500 = 500 W/m² from the hotter body to the cooler. The cooler body cannot heat the hotter body. It is reducing LH's rate of cooling by the 500 W/m² RH provides. In this example, the heater is providing 1000 W/m² to the LH body, which is losing a net 500 W/m² to the RH (cooler) one. The LH body will therefore heat up, but the heat energy which causes that comes from the heater.
MS, yes of course the hot coffee will cool in the cooler room, but it will also heat up if bombarded with radiation in the microwave oven. Its temperature will depend on whether it enjoys a net gain or net loss of energy.ReplyDelete
I'm not arguing for AGW theory. I'm just suggesting your explanation loses clarity and logic because you are confusing radiated energy with heat. (As does the NASA picture but to be fair it's a kids book, so it says what the result is not how it happens).
A hot object radiates more energy while a cooler one radiates less, it doesn't radiate none. So the temperatures equalise. Yes simplistacally the 'heat' only travels one way, but that is because while radiation is going both ways more radiation is lost by the hotter body than the other.
It's the difference between what is gained and what is lost that balances the relative temperatures.
So Mr. Anonymous QED, with your experiment then, the desk lamp radiates photons. The photons hit the paper. The paper absorbs a few, re-emits most. Some hit the mirror. The mirror re-emits almost all. Do these re-re-emitted photons dance around the paper? Does the mirror absorb an extra amount knowing that the paper is "brighter" than it is, or does it let some go through? What, exactly, in your thought experiment happens to the photons reflected by the mirror in the direction of the paper?ReplyDelete
Email from Alan Siddons:ReplyDelete
MostlyHarmless wrote: "Note that there's a difference between the two fluxes, surface to GHGs and GHGs to surface. The net flow is from surface to GHGs. That means no net warming from GHGs. It doesn't mean no effect on surface temperature due to the presence of GHGs. It means that GHGs "back-radiation" slows the cooling of the surface.
This is where MostlyHarmless goes wrong, I believe. You know the saying: KISS -- Keep It Simple, Stupid. Heat is energy transferred as the result of a temperature difference. The greater the difference the faster the transfer. This transfer proceeds in one direction only; there is no "net flow." So the temperature of the surface-heated atmosphere can indeed be said to reduce the rate of heat loss from the surface. Notice the term ‘surface-heated atmosphere,’ however. This denotes that the atmosphere has ALREADY cooled the surface! It has done this and keeps doing this by conduction and convection and the impact is considerable. But the point to stress is that ALL of the heated atmosphere is involved here, not just ‘GHGs.’
So can it also be said that nitrogen, oxygen and argon gases heat the surface less than the surface heats them, thus making the "net flow" go from surface to atmosphere? Do you see how odd this sounds? "Net flow" is always used in a radiation context, but when it’s translated into simple terms of heat transfer it falls apart. Heat flow conforms to a temperature difference. Period.
But there’s one detail in this larger picture of heated gases that deserves scrutiny: emissivity. Non-GHGs have a fairly low emissivity, while the earth’s surface is more like a blackbody, a good radiator. Now, there often does come a point at nighttime where the surface temperature falls below the air temperature. THIS is when the gradient reverses and the air will heat the surface. So think: If the air were as good a radiator as the surface, could it perform this function? No, its temperature would fall as fast as the surface does. My conclusion, then, is that we owe this fraction of air-to-surface heating to low emissivity gases like nitrogen, oxygen and argon. For the higher the emissivity the faster the cooling rate. Even for water vapor, ask yourself how it is sustained above the condensation point. By drawing heat from other gases. When those gases begin to heat the surface, then, and thereby cool down, water vapor is forced to go along. So the frost or dew that you see in the morning signals the reverse gradient that occurred at night. If the air were an efficient radiator, however, this reversal could not occur. (Thanks go to Schreuder for this observation.)
In short, radiation is a heat loss mechanism -- always. For any body, surface and air included, if it radiates it cools. To the extent that it does not radiate -- as for instance by storing heat conductively or by having a low emissivity -- it is able to reduce heat loss. That’s how I look at it.
This comment has been removed by the author.ReplyDelete
I am sorry but I think this is wrong. It is a matter of heat transfer by radiation. All things above 0-Kelvin radiate energy. Thermal transfer is a function of Delta T based on Emissive Power (E) defined by the Stefan-Boltzman Law E = sT^4 where s is the Stefan-Boltzman constant which was independently confirmed by Max Plank in 1901. While this was for Black-Bodies, Kirchoff's Law extended calculation to gray bodies.ReplyDelete
In two opposed, parallel and infinite planes, each with different emissivities, absorptivities, transmissivies and Temperatures, the Radiosity of one plane will equal the Irradiation of the other. At equilibrium there will be a net heat flow (at some or all wavelengths) from the higher Temp plane to the lower.
Now if you introduce a third plane between the two wit the same emissivity on each side, that plane will equilibrate to some Temp and change the heat flow. If you change the emissivity of the plane you change the temperature and the heat flow.
While I am a skeptic on AGW, physics is physics.
At equilibrium the temperature is the same for both bodies and there is no heat flow. As stated in the post, introducing a third body may slow the rate of cooling of the warm body, but it does not warm the warm body.
Suggest you take a look at several recent posts at Claes Johnson's site on these topics
Let me try again. There is a continuous interchange of energy between two radiating bodies, with a net exchange from the hotter to the colder. Even in the case of thermal equilibrium, an energy exchange occurs, although the net exchange is zero.
Now the two plane problem as stated before. E1 = sT1^4, E3 = sT2^4. Heat transfer will be q/a =(E1-E2)/(1/e1 + 1/e2 -1) where e=emissivity. If Black Bodies e1=e2=1 and q/a =E1-E2. Now introduce the third plane and q/a = (E1 -E2)/(1/e1 + 2/e3 + 1/e2 -2) because black bodies e1=e2=e3=1 so q/a = (E1-E2)/2. The heat transfer is cut in half.
So lets try to relate to "Green House Warming". Plane 1 is like dark space at 3 Kelvin. Plane 2 is like Earth at 300K. At 300K black body emission is at 9.66 micrometer, which is infer-red. If the atm were dry N2 and O2 it would be invisible to this radiation and the problem would be like the two plane problem. Now if we add water vapor and CO2 to the atm, both of which are highly absorptive of 9.66 micrometer wavelength, it is like adding the third plane, which will cut the heat transfer between Earth and Space, and warm the atm.
While this is a very simplistic analysis; ignoring incoming spectra, convection, conduction, evaporation, condensation, spinning globe, etc, etc. To imply that the addition of water vapor and CO2 to the atm did not result in an increase in atm Temp is wrong. I don't think adding additional CO2 to atm will raise the temp now because most all of the IR is already being absorbed.
None of this infringes on either the first or second law of thermodynamics.
from Claes Johnson:ReplyDelete
Yes, waves travel in both directions, but what they carry/deliver = net heat energy, only goes one way: from warm to cold. A blackbody subject to incoming radiation (like the Earth subject to radiation from the Sun) reads the temperature of the incoming radiation from its spectrum (mainly in the visible range emitted at 5778 K from the Sun), compares with its own temperature (15 C), notes that 5778 K is bigger and then decides to absorb and then heat up/radiate infrared until equilibrium. If the incoming radiation has lower temperature, then it is directly emitted without heating effect.
It is thus necessary to distinguish between waves traveling both ways, and energy absorbed and stored as heat, which only goes one way.
Brian H sa...ReplyDelete
If an atom can be heated only by incident radiation at a higher frequency than its own resonant emission frequence at its starting temperature, then the ground (hotter) cannot turn radiation from the atmosphere (cooler) into heat, but will immediately reflect or re-emit it:
"...radiative heating by low frequencies is inefficient."
So it is not simply "net heat" which is unidirectional, but the ABSORBABLE radiation: downwelling 'cool' (low-frequency) radiation has little effect on warmer material, bodies, or atoms.
All EM fields are Vector quantities and must be treated as such.ReplyDelete
This includes SUPERPOSITION of the Vector Fields.
Here is the Heat Transfer equation:
"Radiation is heat transfer by the emission of electromagnetic waves which carry energy away from the emitting object."
P = e*BC*A(T^4 - Tc^4)
Where P = net radiated power (Watts), e = emissivity, BC = Stefan's constant, A = area, T = temperature of radiator and Tc =
temperature of the surroundings or another body.
..when rearranged gives
P/A = e*BC*T^4 - e*BC*Tc^4 (Watts/m^2)
This is an obvious subtraction of two Electromagnetic Fields
It also complies with the Vector subtraction of Electromagnetic Fields which are Vectors.
There is absolutely no energy flow from cold to hot, complying with the 2nd Law.
-The Earth receives Solar Energy from the Sun (the Only energy source) = 390.1 w/m^2.
-Earth Surface at +15 deg C (288K) average temperature radiates 390.1 w/m^2 upward. (complying with The Law of Conservation of Energy and the 2nd Law)
-Atmosphere at -20 deg C (253K) average temperature radiates 232.32 w/m^2 upward AND downward.
Between the Earth and atmosphere the EM fields subtract giving a Resultant EM field Magnitude of (390.10 - 232.32 = 157.78 w/m^2) and a Direction of Propagation towards the colder atmosphere.
There is ZERO propagation towards the warmer Earth.(complying with The Law of Conservation of Energy and the 2nd Law)
Past the atmosphere the EM fields ADD giving a Resultant EM field Magnitude of (157.78 + 232.32 = 390.10 w/m^2) and a Direction of Propagation towards Cold Space.
All the Radiation Energy In, provided by the Sun, 390.10 w/m^2 = Energy Out = 390.10 w/m^2.
The Law of Conservation of Energy and The 2nd Law of Thermodynamics has been complied with at EVERY point.
Another way to look at EM radiation is as a FORCE FIELD.ReplyDelete
"The electromagnetic force is one of the four fundamental forces. The other fundamental forces are: the strong nuclear force (which holds quarks together, along with its residual strong force effect that holds atomic nuclei together to form the nucleus), the weak nuclear force (which causes certain forms of radioactive decay), and the gravitational force. All other forces are ultimately derived from these fundamental forces."
"In physics, the electromagnetic force is the force that the electromagnetic field exerts on electrically charged particles. It is the electromagnetic force that holds electrons and protons together in atoms, and which hold atoms together to make molecules.
"The electromagnetic force operates via the exchange of messenger particles called photons and virtual photons."
"The electromagnetic force is the one responsible for practically all the phenomena one encounters in daily life, with the exception of gravity."
Hot objects are not “spatially aware” any more than a block of wood “knows” that it is supposed to move in the direction of greatest force when two opposing forces are applied
to the block of wood!
- Heat Radiation is accomplished by propagating EM fields.
- EM fields are Force fields, in fact the Electromagnetic Force is one of the four fundamental forces.
- EM fields carry “Photon Energy”.
- Photons have zero Mass.
Is it so surprising that opposing EM fields and corresponding Forces will only move the zero mass Photon energy in the direction of the larger force?
The “block of wood” analogy should be apparent except that, unlike a “block of wood”, a Photon has zero mass.
Hot objects produce a larger EM field (and force) than Cold objects so heat energy can only flow from Hot to Cold!….The direction of the larger force!
This is really what 2nd Law of Thermodynamics is fundamentally saying!
“Second Law of Thermodynamics: It is NOT POSSIBLE for heat to flow from a colder body to a warmer body without any work having been done to accomplish this flow. Energy will not
flow spontaneously from a low temperature object to a higher temperature object.”
When AGW’ers say that Heat can flow from Cold to Hot it’s like saying the “block of wood” will move in the direction of the weaker force!
Thanks for your always helpful comments and welcome back!
Hmm. On JoNova's blog, there's a post that says that the Greenhouse theory DOESN'T violate the 2nd LoT. I'm a bit confused. Does it, or does it not? I posted the link to that blog on another post.ReplyDelete
It does violate the 2nd law for the reasons above in this post. Suggest you read all the comments at JoNova as well, including those who disagree with Jo.ReplyDelete
It also violates the 1st law:
simple explanation of why the K-T Earth Energy Balance is wrong - you can't just add radiation fluxes!ReplyDelete
I notice that few people ever take TIME into consideration and the immense age of the earth. If present climate science were true, the earth should have cooked to a crisp long before humans or even plants arrived on the scene, and therefore we should today be no different to Venus, though perhaps a little colder, due to our greater distance from the sun. We should have a runaway Greenhouse Effect with enormous entropy. Moreover the crisis would cycle from a bad state to a worse state. Yet we are nothing like Venus. Climate scientists say the earth is a closed system, kind of like a sealed bottle left out in the sun. It has some water in the bottom and additional gaseous carbon is being constantly pumped into it. Of course any model based on this assumption will show exponential heating and conditions that would rapidly kill off all life. The irony is that even in the absence of gaseous carbon, most kinds of life would be extinguished in such a closed system. The earth has in the distant past endured natural toxic atmospheric events, which have resolved over millions of years. Given the immense age of the earth, clearly atmospheric heat is not continually building like a pressure cooker without release and there must be mechanisms, apart from plant life and the deep oceans, that are dealing with heat dissipation. Of course the oceans and land (rocks) gradually absorb carbon over time, but I believe there is something else going on that scientists are presently totally unaware of. This unseen thing is either sequestering or totally dispatching this additional heat elsewhere. At the present time the earth does seem to be heating slightly, especially in the northern hemisphere, while cooling in the south. The models all predict a runaway Greenhouse Effect scenario in a very short space of time, yet as the years go by the planet continually defies the predictions. Clearly something else is dealing with the heat that the scientists are unaware of. I am not talking about God of course. Perhaps there are tiny, as yet undetectable black holes all through the fabric of reality that seek out ("feed off") errant energy. Perhaps dark matter or that certain percentage of the universe that "is missing" are responsible. We only know about the present Laws of Thermodynamics. Perhaps there are more Laws to add to these, but we are presently not seeing them?ReplyDelete
The 2nd law also explains why the alleged increased heat uptake by the oceans cannot cause significant global warmingReplyDelete
Werner Brozek says:
November 13, 2013 at 9:12 am
We have all of this talk about huge numbers of Hiroshima bombs and about all of the 10^22 Joules the oceans are taking up. But when converting to degrees C, there seems to be almost nothing left as was pointed out in this article. I will illustrate the facts in another way.
I will use Figure 5 and assume it is true.
According to this diagram, the total heat increase is about 25 x 10^22 J over about 55 years.
The total mass of the ocean above 2000 m is 48% of the total mass of the ocean.
The total mass of the ocean is 1.37 x 10^21 kg.
The specific heat capacity of ocean water is 4000 J/kgK.
Applying H = mct, I get a change in t of
25 x 10^22 J/(0.48 x 1.37 x 10^21 kg x 4000 J/kgK) = 0.1 K. Is that correct? If so, it would take over 100 years for the top 2000 m to go up by 0.2 C. Is that supposed to be a problem for us?
Vince Causey says:
November 14, 2013 at 12:41 pm
“Applying H = mct, I get a change in t of
25 x 10^22 J/(0.48 x 1.37 x 10^21 kg x 4000 J/kgK) = 0.1 K. Is that correct? If so, it would take over 100 years for the top 2000 m to go up by 0.2 C. Is that supposed to be a problem for us?”
I doubt it. This is the second law of thermodynamics at work – the entropy is increasing. Useful heat is being degraded into a more diffuse, low grade form.
It’s like taking a red hot poker and dropping it in a bath of cold water. The heat of the original red hot poker can be used to do some work, but once the heat is transferred to the bath, the temperature becomes that of the bath, whose temperature has risen by only a tiny amount.
The important point is that the heat, once diffused to a lower temperature, can never result in a subsequent rise in temperature, which would be contrary to the first law. Therefore, any heat, once sequestered by the oceans, can never reverse its thermodynamic pathway, and reheat the atmosphere to the temperatures that caused it to be absorbed in the first place.
It is an admission that the problem (if it ever existed), is being solved by nature once and for all.
Joe Postma explains why heat only flows from hot to cold [2nd law] from quantum mechanicsReplyDelete
Actually QM was derived by solving the “radiation trapped inside a cavity” problem. That is the origin of QM. The problem was in solving how EM energy would populate all available energy states given an enclosure – what would be the distribution of this EM population of energy states? Before it was solved they had the Rayleigh-Jeans Law and the old UV Catastrophe problem, etc. Then Planck thought of quantization, found that it gave a distribution which was finite, and subsequently this became the discovery of the blackbody spectrum and quantum mechanics as a field unto itself. So if you’re talking about a cooler spectrum (lower energy state population distribution) and a warmer spectrum (higher energy states population distribution), then the higher energy states always want to fill up the lower ones…because they’re available to. The lower energy state population distribution can’t fill up any more of the higher ones, because 1) the higher ones are already populated, 2) it doesn’t contain populated energy states that are higher in energy than the higher energy population, by definition. So, with the cooler spectrum unable to contribute any more “population” to the warmer spectrum, but the warmer spectrum can certainly do so for the cooler one, then heat flows hot to cold, where heat flow is the higher energy state population from the warmer spectrum going over and filling up the cooler one’s. The reason why this happens is called “spontaneous”, but it’s actually a rather simple statistical necessity – energy moves around, and there’s lots of it, like 10^32 photos per second from a 100W light, and so given such a large number of numbers, they find their way anywhere they can go. Like molecules finding their way into a vacuum. 10 photons or molecules distributions wouldn’t do much…but 10^32 simply necessitates that “the numbers go where there is a relative void of numbers”. The relative void doesn’t increase the numbers of the higher/denser number distribution.
Bill Illis says:ReplyDelete
January 27, 2014 at 4:46 pm
After being in this debate for a long time, I’d say I still haven’t seen anyone show me how CO2 does what it is supposed to do.
The only factual thing I’ve seen demonstrated is that CO2 is an efficient emitter of energy from the atmosphere to space at between 10 kms to 20 kms high where it is -53C or 220K. That technically means CO2 cools the atmosphere, not warms it.
Its not like I am incapable of understanding or even if that matters at all. Its just that NOONE has shown how it works. There are 2 papers which pop out a “forcing” number supposed based on Modtran and Hitran but they explain absolutely nothing. They just produce a number. And then there is the feedbacks, partially based on a real meteorology, but perhaps not, that seem to highly “tuned” to pop out further temperature increases along the lines of the theory as I have deconstructed it. Highly tuned, as in, change the feedback parametres by 25% and the whole thing falls apart.
But that is all there is to the story.
If someone has more to add in terms of explaining it, I’d sure appreciate it.
george e. smith says:ReplyDelete
January 27, 2014 at 5:31 pm
“”"”"…..Mike Borgelt says:
January 27, 2014 at 2:00 pm
I haven’t seen any WUWT comment on this:…..”"”"”
An interesting post ; izzat Steve Goddard’s web site ??
The general gist of his post is something I have railed on for some time, but absent the info, on what IR astronomers see glaring them in their eyes (IRIs).
At the presumed 288 K earth surface Temperature (maybe 287 K), the calculated BB spectral radiance peak is at 10.1 microns (on spectral radiance per micron wavelength; not per wave nummer plots).
from stuff you learn in the 8th grade science, or maybe 4-H club science; you are supposed to have remembered that exactly 25% of all BB radiant energy lies at wavelengths shorter than the peak wavelength. Also, that only 1% of BB radiant energy lies below half the peak wavelength; and only 1% of the total energy lies above eight times the peak wavelength.
So for a 288 K BB, we have a 10.1 micron peak, and only 25% is below that, and the 1% limits are at 5.05, and 80.8 microns.
Now the 10.1 microns is in the so-called “atmospheric window”, but as the astronomer emeritus said, the 9.6 micron Ozone hole is in there too.
Now 10.1 microns may be the 288 K mean surface Temperature emission spectrum peak; BUT !!
at that Temperature (15 deg. C) the total radiant emittance is 390 W/m^2. Look for that nummer on Kevin Trenberth’s budget cartoon. So what is it like when the surface Temperature is 333 K or + 60 deg. C as in the equatorial deserts, where the earth is really cooling off at a high emission rate.
Well (333/273)^4 = 1.787 which now gives us 697 W/m^2 of cooling emittance.
But hang on . At that Temperature, the spectral emission peak has shifted due to Wien Displacement, and is now at 8.735 microns, and not 10.1.
Now even further into the window gap, and now even below the Ozone hole. Moreover, it is now further removed from the 15 micron CO2 degenerate (double) bending mode band; so CO2 is even less effective (but the spectral emittance at the CO2 band is still higer; but nowhere near 78.7% higher.
Of course, these equatorial deserts are as dry as a bone, so the atmospheric moisture content is way down; which is why the air Temperature crashes at sunset.; so the escape of this 78% higher emittance is further enhanced by the lack of water GHG effect.
Now the full calculation is a bit more complex. From your 4-H club you learned that the PEAK spectral radiant emittance increases as the FIFTH power of the Temperature; Not the FOURTH power.
So the narrower spectrum around the 8.7 micron peak, within the atmospheric window is actually more like 2.067 times the value per micron, at 288 K.
Which is why I have claimed for quite some time, that it is the tropical deserts and other location (UHIs as well) with their higher Temperatures, which are doing the planetary cooling chore; not the frozen wastelands (and seas) at the poles.
So what of those polar regions. Antarctica, we now know regularly gets down to – 94 deg. C , or about 179 kelvins.
So now the BB emittance spectral peak has shifted out to 16.25 microns; almost past the entire CO2 band. The total radiant emittance has dropped to only 14.9% of its 288 K value; or just 58.2 W/m^2. The shifted peak spectral emittance has dropped to just 9.3% of its 288 K value.
So the polar regions, have very little to do with the radiative cooling of the planet; even though CO2 develops its full GHG potential at those Temperatures. There’s very little radiative cooling going on at the poles for CO2 to have much influence there, on global cooling or warming.
So I checked my car’s radiator. It runs damn hot; hotter even than the Sahara. But it sure does cool like a Coors lite ( a near beer; same as Millers).
Physics Illusion 2: Two-way Photons Carrying Light (Energy)ReplyDelete
Computational Blackbody Radiation describes radiative energy transfer as a resonance phenomenon between two resonators connected by a vacuum carrying electromagnetic waves.
In this model the finite speed of electromagnetic waves only influences the energy transfer in a start up phase, while in a stationary state of standing waves the energy transfer can be viewed to be instantaneous without time delay, or to be without time aspect. The transfer of energy is one-way from hot (high frequency) to cold (low frequency).
In this view there is no need to introduce particles named photons carrying energy packets at finite speed back and forth between the resonators, as if the resonators were connected by a two-way highway with trucks transporting energy in both directions, with more trucks from hot to cold and a net flow of energy from hot to cold. There is no experimental evidence of such a two-way energy transfer
by photon particles or light quanta emitted by distant galaxies and traveling at finite speed to hit our eyes after 13 billion years:
All these fifty years of conscious brooding have brought me no nearer to the answer to the question, 'What are light quanta?' Nowadays every Tom, Dick and Harry thinks he knows it, but he is mistaken. (Albert Einstein, 1954)
the second law states that dS/dt ≥ 0 for any closed system (or the total entropy of a closed system is either constant or increases with time.)ReplyDelete
And Clausius’s principle states that a thermodynamic process cannot transfer net heat energy from an object at a lower temperature to one at a higher temperature without work being done on the system.
Both of these are valid, regardless of whether the atmosphere is adiabatic. It occurred to me that David Appell may have been confused over what a closed system is in thermodynamics.
Briefly it is a system in which no mass is transferred between the system and its environment and for which no interactions occur with the external environment other than the exchange of heat energy.
As I said below, the 2LOT wouldn’t be very useful, if you couldn’t apply it to non-adiabatic systems.
Also the confusion over Clausius is possibly because the statement of Clausius’s principle involves no net heat energy exchange from a colder body to a warmer one without work being done on the system.
The key word here is “net”.
Green houses gases DOES NOT radiate the heat but acts as a mirror which reflects the upward thermal radiations from earth surface. That is how they confine upward thermal radiations within the atmosphere, more specifically troposhpere. On the other hand, the incident solar ray manages to enter the atmosphere a) because CO2 layer acts as transparent glass for SHORT WAVE solar rays b) because the Karman line (boundary between space and atmosphere) is at 2000 degree Celsius. So second law is not violated.ReplyDelete
the atmosfere is not a glass wall and neither a mirror. It is a continuum. The most C02 concentration is on the ground decreasing continuosly versus stratosfere. On the other hand if there is a C02 warming effect - and it can't be - it will increase also water condensation and therefore cloud building that lacks incoming sun energy which has a cooling effect. Simple models in high complex systems don't work. By the way, In all that discussion i miss considerations of earth rotation kinetic effects...Is the incoming sun engery sufficient for warming the atmosphere at all? I have some doubt....ReplyDelete