Bishop Hill Climatologists respond
Feb 1, 2012 "Travesty" Trenberth et al are in the Wall Street Journal today, taking issue with last week's letter suggesting that panic over global warming is not required. Presumably, the message from the scientific establishment is that panic is a necessity.
It's pretty dull stuff - "97% of climatologists whose funders expressed a preference" - that kind of thing. But I was struck by this:
Climate experts know that the long-term warming trend has not abated in the past decade. In fact, it was the warmest decade on record.
I do wish people would make it clear where the differences lie. Otherwise we will get nowhere. Sceptics note that the temperature has flatlined since the turn of the millennium. Upholders say this means nothing, it's just a pause, and the long-term trend remains upward. Fine. Maybe we should talk about model falsification or something.
But take a look at that sentence again. I don't see how the long-term trend (normally assessed over 30 years) can not have been abated to some extent by a 10-year flatlining. Is the maths they use in climatology a bit different?
Reader Comments (160)
RE: ". . . Upholders say this means nothing, it's just a pause, and the long-term trend remains upward."
And this bit, that could have been penned by Trenberth, Hisself:
"And computer models have recently shown that during periods when there is a smaller increase of surface temperatures, warming is occurring elsewhere in the climate system, typically in the deep ocean."
I recall that when the 'Distinguished Senior Scientist' Trenberth had some difficulty on his Holy Quest to Find The Missing Heat, in actually finding the missing heat, his pals came to the rescue by programming a computer model to show the heat was where he said it was to be found. So it was only a matter of time before that model would become the 'consensus' proof of a theory that the model was programmed to prove. (I'm sure it was more complicated than that, but . . .)
I note Kev is the only one listed on that letter with a Sc.D. Does a Sc.D also come with the designation of 'Distinguished Senior Scientist'? Or is the DSS more of a 'self-appointment'? And it appears DSS Trenberth, Sc.D is one of only 2, without a Ph.D.
So to paraphrase Doc Trenberth et al; would you allow your Doctor to treat you for something their computer was programmed to find in you but, to date, no blood test, x-ray, or 'rubber-glove' examination was able to find?
-barn
http://theendofthemystery.blogspot.com/2010/11/venus-no-greenhouse-effect.html
That's a simple elegant explanation of why AGW is a load of bollocks.
I, like Martin A, still don't understand what MDGNN is banging on about, can someone explain
it simply?
Feb 2, 2012 at 12:31 PM | Nial
If AGW is "a load of bollocks", what's the point of discussing the finer points of the mythological 'back radiation' supposedly responsible for it?
Hi Nial: I'm not saying AGW is a load of bollocks only that the present explanation that it is due to GHGs acting as a sort of electric blanket' around the Earth cannot be true.
The claim that it is a second heat source besides the IR emitted from the earth's surface is nonsense yet it is routinely claimed by its proponents. And it's not just me saying it, it's EVERY engineer I have ever met who has had process engineering training, also EVERY physicist I have ever met, so long as i leave them enough time to be able to collate their thoughts in terms of the practical World!
So, it's a sort of blanket but there can be no positive feedback whereby half the ~20% of the IR from the Earth which is 'captured' is re-radiated downwards to add to the initial radiation and 20% of that 110% is intercepted making it 121% etc giving positive feedback that could give infinite thermal runaway and make us another Venus.
The reality is that most of the heating of the atmosphere near the Earth is convective and although the warming of the local atmosphere does produce radiative energy you can measure when you shield the detector from IR going upwards, it can do no thermodynamic work by adding to the temperature of the earth's surface..
Furthermore, most of that ~20% of the IR is in fact absorbed at second phases such as cloud droplets, even on the horizon, so is widely dispersed as local latent plus sensible heat, not a rise in temperature of the air away from clouds.
I do not know what this will do to the climate models, but I suspect it will significantly change the projected temperature rise, possibly rendering extra CO2 irrelevant insofar as the changed convection due to the subsequent accelerated precipitation of water will drive convective short circuiting of GHG temperature rise to the upper troposphere faster: result much lower CO2 climate sensitivity.
In short, the present approach is fundamentally wrong in my not so humble opinion. As for most recent real warming, it involves different processes with natural changes of cloud albedo and cloud area.
In short, the present approach is fundamentally wrong in my not so humble opinion. As for most recent real warming, it involves different processes with natural changes of cloud albedo and cloud area.
Feb 2, 2012 at 3:23 PM | mydogsgotnonose
Am I right to infer from your post that you regard AGW to be insignificant?
RKS: There is GHG warming because you measure so-called 'DLR', really Prevost Exchange Energy, from a clear sky and you can't get that unless there is absorption of IR from the Earth’s surface by GHGs. However, I also happen to be an expert on heat transfer to and from air containing GHGs having designed metallurgical heat treatment processes - we even made our own radiometers and pyrometers from basic physics.
So, when I saw the mistakes in climate science, originating from Fourier, Tyndall and Arrhenius, I got worried. And then I saw this: http://geo.arc.nasa.gov/sgg/singh/winners4.html
There is no such 'surface reflection' physics. It was substituted for Twomey’s correct physics apparently to justify experimentally unproven ‘cloud albedo effect cooling’ in AR4, the only purported evidence for ‘high feedback’. Climate science swallowed it but not me.
So, I set out to establish the real science. Anyone who thinks I’m wrong should tell me why!
> If AGW is "a load of bollocks", what's the point of discussing the finer points of the mythological 'back
> radiation' supposedly responsible for it?
The pursuit of knowledge?
I'm an engineer, I want to know how it (doesn't) work.
Nial
When I said AGW is a load of Balearics, it was _C_AGW I was referring to.
I do accept that man's activities have warmed the planet to some miniscule degree.
Nial.
When I said AGW is a load of Balearics, it was _C_AGW I was referring to.
I do accept that man's activities have warmed the planet to some miniscule degree.
Nial.
Feb 2, 2012 at 6:55 PM | Nial
As another engineer (retired) I'm in general agreement with your assessment.
That's why I asked MDGNN for his opinion on the significance of AGW.
> If AGW is "a load of bollocks", what's the point of discussing the finer points of the mythological 'back
> radiation' supposedly responsible for it?
The pursuit of knowledge?
I'm an engineer, I want to know how it (doesn't) work.
Nial
Feb 2, 2012 at 6:52 PM | Nial
Until someone comes along with a halfway rational explanation of how they imagine 'back radiation' functions, it's a bit difficult to argue how it doesn't work - I think!
Nial
Consider that the atmosphere weighs as much as a thirty foot depth of water- roughly ten tonnes per square yard.
Immerse yourself halfway down, and things look blue in all directions because in considerable thicknesses, the 'clear ' water is anything but colorless. In the equally massive atmosphere , the absorption of many dilute gasses comes into play, with some spectral lines narrow and others broad and overlapping,
Since it is axiomatic that molecules can emit as well as absorb at the various frequencies that excite both optical and vibrational modes of quantized motion and these are each of specific central frequencies, the atmosphere has an extremely complex overall spectrum, the sum of many spectrally narrow parts instead of a smooth blackbody curve,
try googling 'AFCRL tables', then hit the' images' selection and you can see what you are up against - each of those hundreds of spectral lines has an emissive counterpart, and many of them absorb in the thermal infrared spectrum, and just as the molecular density of each depends on altitude, so do the linewidths on pressure, each with its own rate of change. So how can you make quantitative sense of this?
The answer is by finite element iteration and integration- a system of differential equations many layers deep can readily, albeit complexly , describe this reality and all it takes to solve such a system is a few man years of blackboard calculation, or a few microseconds of running a microchip.
Taxpayers concerned with climate should therefore be very thankful scientists are frugal enough to insist on the latter method, called computer modeling.
As to Martin, perhaps he should lay aside his concern with acronyms and pick up a sophomore climate science text. McElroy's , from the Princeton press is pretty good, though it stumps poor Gore, as is Pierrehumbert's- you can get the textbook, and watch the whole course, including lectures and demonstrations free of charge online courtesy of that hotbed of free market economics, The University of Chicago.
I certainly hope you will, for tory policy needs to engage environmental reality if it is to defeat those who view climate change as a splendid pretext for societal intervention. That means getting real about the science.
Feb 1, 2012 at 7:40 PM | Martin A
//////////////////////////////////////////////
Matin
I applaud your attitude.
I am not sure your analogy is wholly sound since don't forget that when you switch on your microwave oven with no food/drink inside it. neither the metal casing nor the glass platter is heated by the microwaves.
Russell: Pierrehumbert is quite good, bit of a fence sitter but independent of the loonies like Hansen.
Look very carefully at his pea under the thimble re 'back radiation'' because the independent thinkers like Curry are deferring to him. He is becoming the US gatekeeper.....
Over here, the climatology establishment appears to be regrouping under the 'back radiation' banner because they realise that without that they stand to lose influence.
That means people who question the status quo too hard are being told to be quiet or publish and never be peer approved. This fight will come to a head but only when the US comes under new scientific leadership - not yet.
RKS Feb 2, 2012 at 10:21 AM |RKS
I've been put off by reading "Slaying the Sky Dragon" by some "scientists" claiming to refute the greenhouse effect. Have you read it? It's garbage. Although to someone who does not know physics, it would read mostly as lucid good sense.
Dognose said that what he's going on about is explained in standard texts. I asked for a reference to one or two but he did not come up with one.
I want to read about what he's saying in a standard textbook on the physics on radiative heat transfer - not someone with a pro (or contra) AGW axe to grind.
Huffman's noticing the similarity between the temperature profiles of Venus's and Earth's atmosphere is a remarkable discovery. But it's an observation, rather than an explanation of why the greenhouse effect is bollocks.
richard verney Feb 3, 2012 at 3:07 AM
Why thank you.
I think the analogy also holds there. IR radiation from a hot body is ineffective at heating (shiny) metal - because shiny metal reflects it. And the inside of a microwave oven reflects the microwave radiation, because it's electrically conductive - fundamentally the same reason the shiny metal reflects IR.
As a side question, where does the energy go in an microwave oven with nothing in it?
I think the answer is that the magnetron will find itself working into a load presenting it with a very unpleasant standing wave ratio and, despite under such conditions producing some very high microwave frequency voltages, its output power will be far, far smaller than when it is working into a reasonable load impedance.
The small amount of power it does manage to produce will presumably warm the case of the microwave somewhat as a result of the eddy currents generated in the imperfectly conducting steel. Note that waveguides in microwave communication systems etc are made from copper - the losses if steel were used would be too great.
Russell, that's just impressive sounding waffle that doesn't actually explain anything.
To summarise....
The atmosphere contains many different gasses that absorb and emit at different frequencies depending on their altitude and therefore pressure. And you can work out the effect of the 'pile' of molecules using a computer.
So what?
This doesn't explain MDGNN's point at all.
"Taxpayers concerned with climate should therefore be very thankful scientists are frugal enough to insist on the latter method, called computer modeling."
Are you saying that we should be grateful to climate 'scientists' because they don't insist on working out the result of their 'models' by hand?
:-)
Nial
MDGNN
I can see why, if you believe that that is the explanation given for how the greenhouse effect works, you also believe it amounts to positive feedback, energy out of nowhere, thermal runaway etc.
I think you have misunderstood the explanations given which, so far as I can see, do not state or imply what you have said.
I don't want to make a fool of myself but....
If a molecule is heated by an incident IR souce, does it not radiate a percentage of this in all directions?
I think the answer is yes.
In an atmosphere with no 'greehhouse gasses' there is a temperature gradient from the surface of the
earth to ambient of space.
If I layer of molecules, which asborb and re-radiate some of the IR radiation emitted from the earths
surface, is added near the surface then surely this must re-radiate some of theIR back down towards the
surface. (The longer wave IR radiation from the sun magically passes through un-impeded).
The temperature at the surface is therefore increased over the non-greenhouse gas situation?
Can someone explain why this isn't the case?
Thanks,
Nial.
Russell Feb 3, 2012 at 1:45 AM
Russell, have you been paying attention?
MDGNN repeatedly says that standard climate science has got it all wrong. So what I want is not a standard climate science text but something that explains it from MDGNN's perspective, with warming by IR radiation apparently being controlled by quantum level interactions taking place possibly kilometres apart, black bodies not absorbing photons originating from insufficiently hot bodies and so on.
Hi Nial: A photon is a quantised packet of energy that travels through space as the result of the simultaneous operation of a perturbation of electric and magnetic fields at right angles to each other. The direction of motion is perpendicular to these fields. The velocity is the speed of light.
So, because the emitting molecule has a random orientation. you have a random direction and straight-line motion of the photon.
As for the temperature of the surface, this is determined by the SW energy coming in, the convective heat transfer and the IR radiated at that temperature. The sum of the convection and radiation is constant with the control of the radiated IR, in effect the operational emissivity/absorptivity of the surface, determined by the proporton of its IR density of states that is filled by the 'DLR'.
The DLR is a function of the temperature of the air and its emissivity. None of that DLR energy heats the surface: all it does is to vary the rate of conversion of thermal energy of the solid into emitted IR. This is a very complex bit of physics which is why few in climate science have a clue about it and engineers talk of operational parameters rather then the theory!
When the air is at the same or lower temperature than the Earth's surface, DLR aka 'back radiation' is a regulatory principle to do with the radiative heat transfer. Except at very low temperatures when quantum effects dominate, it cannot ever be converted to heat energy in the solid because that would conflict with the 2nd law of thermodynamics.
Hi Martin: what you must realise is that the earth cannot be a black body. The only black body is an absorptive cavity.
So, the radiative equilibrium with air containing GHGs is complex because of the mechanism which means emissivity equals absorptivity in any wavelength interval, Kirchhoff's Law of Radiation, and GHGs emit and absorb in narrow wavelength intervals.
So, what you have is selectively filled IR states on the solid surface and the number of these is related to the IR states in the gas. Read Hoyt C. Hottell's works.
If you want a simple view, there isn't one. It's because this physics is the most basics of all sciences and to get to it you have to be educated to a high level in physics. Climate science hasn't a clue as proved by its belief in 'back radiation'!
> So, because the emitting molecule has a random orientation. you have a random direction
> and straight-line motion of the photon
So the energy is re-emitted in random directions (including some towards the original radiating
surface)?
> it cannot ever be converted to heat energy in the solid because that would conflict with the 2nd
> law of thermodynamics.
I think you're saying that the surface itself won't be heated above it's initial temperature.
That's self evident I think.
> As for the temperature of the surface, this is determined by the SW energy coming in, the
> convective heat transfer and the IR radiated at that temperature.
OK, but the total IR radiation 'flow' is reduced by the small amount be re-radiated back 'down', so
the surface temperature increases (slightly)?
No?
Nial
MDGNN
Well, yes - it's an idealisation . But some things come close enough to be treated as black bodies for engineering purposes. What level of emissivity would a thing have to have for you to consider it a black body? 0.9? 0.99? 1.00000000000000000 ?
Of perhaps "none of the above" because, I think, you are saying that absorption/emission by the earth's surface follows the same mechanisms you consider are involved in absorption/radiation by gases.
Science of Doom (yes, you have explained what you think of them) reproduce data showing the earth's surface (for the longwave IR range, I assume) has emissivitiy in the range 0.8 - 0.99.
http://scienceofdoom.com/2010/04/07/the-dull-case-of-emissivity-and-average-temperatures/
[I'm not sure if by "the earth" you are talking about the earth as a whole, with its atmosphere included, or just its surface. The latter - right?]
Any chance of a reference? Amazon does not seem to list anything by him. Does what he covers explain your viewpoint on IR radiation/absorption?RKS Feb 2, 2012 at 10:21 AM |RKS
Take a look at the work of Ned Nikolov, Ph.D. & Karl Zeller, PhD. on the United Theory of Climate thread on this blog, and perhaps also the work of Prof. Harry Huffman in this paper :- http://theendofthemystery.blogspot.com/2010/11/venus-no-greenhouse-effect.html
for examples of the many scientists now refuting AGW.
I've been put off by reading "Slaying the Sky Dragon" by some "scientists" claiming to refute the greenhouse effect. Have you read it? It's garbage. Although to someone who does not know physics, it would read mostly as lucid good sense.
Dognose said that what he's going on about is explained in standard texts. I asked for a reference to one or two but he did not come up with one.
I want to read about what he's saying in a standard textbook on the physics on radiative heat transfer - not someone with a pro (or contra) AGW axe to grind.
Huffman's noticing the similarity between the temperature profiles of Venus's and Earth's atmosphere is a remarkable discovery. But it's an observation, rather than an explanation of why the greenhouse effect is bollocks.
Feb 3, 2012 at 12:12 PM | Martin A
I've no idea what this "sky dragon" publication is or what it has to do with the work of N&Z or Huffman.
And for a person who's looking for ways to refute 'back radiation' , I find your criticism of scientists who refute AGW as a bit odd.
Perhaps your agenda is to refute those who refute 'back radiation'. But there again, how can one offer up a scientific reason to refute something that does not exist.
At least Huffman bases his observations on empirical data rather than convoluted mind games.
You press others to offer sound reasons why the greenhouse effect is bollocks, which is a touch disingenuous really.
The argument has settled on whether increased CO2 is responsible for global warming. If not, conducting mind games to show how it happens are a pointless exercise in philosophy in trying to prove a negative.
Can you show us, beyond question, if CO2 is responsible. If you don't believe that, why are you asking others to prove your prejudices for you and adopting a somewhat offhand attitude to scientists with alternative theories.
Have you read N&Z's theory and if so, can you offer any scientific critique other than criticising some book that only zealots might want to read?
Martin A
I know that, and what the others say are all correct, and basically all the same thing. That is causing you to get lost in the details -- to use an analogy, you are lost in studying the vein patterns of trees in the forest instead of paying attention to the forest. MDGNN is a very smart and capable engineer and he knows a great deal more about thermodynamics than I could even dream about. And while I can follow his arguments, it is clear he is leaving you in the canopy of the forest looking at details instead of the big picture, which you apparently do not fully comprehend.
The basic facts are:
The well proven Thermodynamic Laws, which we all live by do say that you can't boil water by placing ice in it because the water has more heat per molecule of water than the ice (frozen water) has. Yet both are radiating a great deal of heat. All you have to do is drop some ice into a flask of liquid nitrogen (which is a great deal colder per molecule than the ice) to see a massive explosion of gaseous nitrogen as it boils off. What has happened is the ice was so much hotter than the liquid nitrogen that is was just as you dropped a white hot poker into the water vat in a blacksmith's shop.
So remember the simple rule: You can't boil water -- or even heat it up -- with ice. The water already contains more heat per molecule than the ice.
That pretty much covers the thermodynamics.
The second issue is how can you move heat energy from a colder spot to a warmer spot. You can do that in a number of ways, but they all depend on you to reflecting (as with a mirror) or refracting (as with a lens) the radiating energy going from a cooler object like ice to a warmer one.
Here is a perfect example:
The solar energy is being reflected onto the tower. What is actually happening is the energy that would have been spread over the surface of the earth is being reflected back to a single point, collecting it, and in sum, the total amount of energy is greater than already on the tower, so it heats it.
You can also do it with a lens. Ever start a fire as a child with a lens? Same effect. The energy impinging on overall surface of the lens is redirected into a single spot, thereby increasing the temperature to the flash point of the paper or whatever you are focusing it on.
When I said "Show me the mirror" I was simply saying that in all of the fancy designs I read about in your various postings, I saw nothing that even remotely functioned like a lens or a mirror. Without that, you can not concentrate the heat energy. Think about that.
Martin A
I know that, and what the others say are all correct, and basically all the same thing. That is causing you to get lost in the details -- to use an analogy, you are lost in studying the vein patterns of trees in the forest instead of paying attention to the forest. MDGNN is a very smart and capable engineer and he knows a great deal more about thermodynamics than I could even dream about. And while I can follow his arguments, it is clear he is leaving you in the canopy of the forest looking at details instead of the big picture, which you apparently do not fully comprehend.
The basic facts are:
The well proven Thermodynamic Laws, which we all live by do say that you can't boil water by placing ice in it because the water has more heat per molecule of water than the ice (frozen water) has. Yet both are radiating a great deal of heat. All you have to do is drop some ice into a flask of liquid nitrogen (which is a great deal colder per molecule than the ice) to see a massive explosion of gaseous nitrogen as it boils off. What has happened is the ice was so much hotter than the liquid nitrogen that is was just as you dropped a white hot poker into the water vat in a blacksmith's shop.
So remember the simple rule: You can't boil water -- or even heat it up -- with ice. The water already contains more heat per molecule than the ice.
That pretty much covers the thermodynamics.
The second issue is how can you move heat energy from a colder spot to a warmer spot. You can do that in a number of ways, but they all depend on you to reflecting (as with a mirror) or refracting (as with a lens) the radiating energy going from a cooler object like ice to a warmer one.
Here is a perfect example:
The solar energy is being reflected onto the tower. What is actually happening is the energy that would have been spread over the surface of the earth is being reflected back to a single point, collecting it, and in sum, the total amount of energy is greater than already on the tower, so it heats it.
You can also do it with a lens. Ever start a fire as a child with a lens? Same effect. The energy impinging on overall surface of the lens is redirected into a single spot, thereby increasing the temperature to the flash point of the paper or whatever you are focusing it on.
When I said "Show me the mirror" I was simply saying that in all of the fancy designs I read about in your various postings, I saw nothing that even remotely functioned like a lens or a mirror. Without that, you can not concentrate the heat energy. Think about that.
Sorry about the double posting, but the Square Peg in a Round Hole's software did at reset and then posted the first copy while I was trying to get it sorted out. Better than it use to be, but still a bit shaky.
RKS
If you want to see nonsense written by some skeptic "scientists" take a look at
Slaying the Sky Dragon - Death of the Greenhouse Gas Theory
I'm neither trying to defend nor trying to refute the greenhouse theory.
For the record, I think that as normally presented, it is far too over-simplified to be of any use in understanding the earth's climate. But that does not mean that the over-simplified model is based on some sort of fallacy involving a misunderstanding of physics .
I do notice people saying things:
- it contradicts the 2nd law of thermodynamics;
(even though, as I read its explanation, heat is only moving from warmer to cooler)
- radiation from cooler bodies cannot be absorbed by warmer bodies
(contrary to any chemical engineering text on heat transfer);
- it involves the creation of energy from nothing;
(even though the explanation is based on power output = power input)
- it implies thermal runaway
(see above)
- it involves positive feedback
None of these things seem to me to be implied in some explanations I have seen. (Others that I have seen strike me as plain gobbledegook eg "carbon dioxide traps radiation".)
MDGNN frequently states that the greenhouse theory on based on incorrect physics. He's not obviously a crackpot and clearly has had a successful career dependent on a deep understanding measurement of radiated heat.
I am simply trying to understand what he is on about. Is that OK with you?
If MDGNN would point to a suitable physics or radiative transfer text that explains what he's referring to, I'm perfectly capable of reading and understanding it. But I'm still waiting.
Don Pablo de la Sierra
Please see the above.
(even though, as I read its explanation, net heat is only moving from warmer to cooler)
RKS
If you want to see nonsense written by some skeptic "scientists" take a look at
Slaying the Sky Dragon - Death of the Greenhouse Gas Theory
Feb 3, 2012 at 3:45 PM | Martin A
Thanks but no thanks.
I find it odd you should bother to read this. I leave the politics of global warming to activists and zealots.
And I'm beginning to feel that you will not accept any explanation offered.
If you can't understand it after all the effort others have put in for you, then perhaps you are simply making mischief.
RKS
Please carefully re-read my Feb 3, 2012 at 3:45 PM posting.
I am trying to understand specifically MDGNN's viewpoint. That's all. Nothing more than that.
Don Pablo kindly pointed out
While this may explain why my efforts to make hot tea with nothing more than the freezer have been less than totally successful, it did nothing to help me understand MDGNN's views about the quantum mechanic interactions between what goes on in a radiating body and an absorbing body.Feb 3, 2012 at 3:45 PM | Martin A
I do notice people saying things:
- it contradicts the 2nd law of thermodynamics;
(even though, as I read its explanation, heat is only moving from warmer to cooler)
- radiation from cooler bodies cannot be absorbed by warmer bodies
(contrary to any chemical engineering text on heat transfer);
- it involves the creation of energy from nothing;
(even though the explanation is based on power output = power input)
- it implies thermal runaway
(see above)
- it involves positive feedback
None of these things seem to me to be implied in some explanations I have seen. (Others that I have seen strike me as plain gobbledegook eg "carbon dioxide traps radiation".)
Feb 3, 2012 at 3:45 PM | Martin A
"None of these things seem to me to be implied in some explanations I have seen"
That's a rather vague conclusion.
Would you care to explain your conclusions above, for the things you quote people saying, with the same level of scientific exactitude that MDGNN showed in his response to your questions of him. Without resorting to vague generalizations of course.
You must have some scientifically informed reasons for the firm opinions you state.
And talking about questions being answered, have you any good reason for not discussing N&Z's theory ruling out the effect of GHE. Surely that's equally as valid as MDGNN's rebuttal of 'back radiation'
Nial : "Can someone explain why this isn't the case?"
His name's Boltzmann. In many curricula, actually passing a course in statistical thermo is a prerequisite for taking one in atmospheric optics, or for that matter, astrophysics.
This thread simply and vividly illustrates the risks of trying to get a quantitative handle on radiative transfer equilibria in real atmospheres ( or for that matter rocket nozzles) without the necessary kit.
Russell
He politely asked for an explanation.
Not a put-down. Let's hear an explanation if you can give one.
Nial : "Can someone explain why this isn't the case?"
His name's Boltzmann. In many curricula, actually passing a course in statistical thermo is a prerequisite for taking one in atmospheric optics, or for that matter, astrophysics.
This thread simply and vividly illustrates the risks of trying to get a quantitative handle on radiative transfer equilibria in real atmospheres ( or for that matter rocket nozzles) without the necessary kit.
Feb 3, 2012 at 5:12 PM | Russell
Repeat questions about the same thing.
No answers to any questions.
Sound familiar?
I think there's a big wind up going on here.
RKS
OK here's another question that I don't expect will get an answer...
RKS
"I think there's a big wind up going on here."
Of course.
MDGNN, with great tact and diplomacy, said:
Can you give a reference to any physics text that explains "I think there's a big wind up going on here.
> His name's Boltzmann. In many curricula, actually passing a course in
> statistical thermo is a prerequisite for taking one in atmospheric optics,
> or for that matter, astrophysics.
> This thread simply and vividly illustrates the risks of trying to get a quantitative
> handle on radiative transfer equilibria in real atmospheres ( or for that matter rocket
> nozzles) without the necessary kit.
More flannel Russell.
Didn't someone say if you can't explain something simply you don't really understand it?
At least I admit I don't understand it.
Nial
Haha I hit the wrong button...
RKS
"I think there's a big wind up going on here."
Of course.
MDGNN, with immense tact and diplomacy, said:
Can you (or Russell) give a reference to any physics text that explains "thermal radiation involves the direct coupling of thermal emission states between emitter and absorber."
Or how thermal radiation is in any fundamental way different from radiation produced by a magnetron?
RKS: you lot need a lesson in heat transfer.
Look at this diagram from Trenberth and Kiehl: www.cgd.ucar.edu/cas/papers/KiehlTrenbBAMS97.pdf The accepted value of the SW radiation from the sun incident on the surface is 70% of the 342 W/m^2 incident on the top of the atmosphere, or ~240 W/m^2. Look at Figure 7: IR supposedly leaving the surface is 390 W/m^2 and 'back radiation' is 324 W/m^2.
What they're doing is to claim that all the heat leaving the Earth's surface is IR from an average temperature of 14.82°C assuming an albedo of unity [5.6704.10^-8.(14.82+273.16)^4 = 390 W/m^2]. This ~15°C is the average temperature of the Earth's surface. The implied air temperature in the composite emitter is ~2°C.
That is rubbish because when the air temperature is less than that of the surface, much of its heat loss is by convection and evaporation so the IR flux is much lower on average. The only way they achieve this imaginarily high IR flux result is by assuming 'back radiation' which adds to the IR coming from the surface.
That is impossible because the radiation coming downwards, a measure of the impedance to IR transport in the atmosphere to space, is used to fill the IR density of states on the composite emitter which, as i will show below, is the Earth's surface and the convectively warmed air above it.This IR is then re-emitted in the merry-go-round we call Prevost Exchange Energy which can do no thermodynamic work because it is never converted to heat.
You prove this by imagining two parallel infinite metal plates, unit emissivity, in a vacuum, at 15°C. If you point a radiometer perpendicular to one plate it will measure 390 W/m^2. if you point the radiometer at the other plate, it'll measure the same. So, these two radiative fluxes exactly cancel each other: no net heat transfer in the gap; Prevost Exchange Energy exactly cancels.
Thus it is that the total of conductive, evaporative and radiative heat transfer from the Earth's surface averages 240 W/m^2 so the radiative flux is much less than you would expect for the absolute temperature of the earth's surface. Engineers treat this problem by deriving an effective heat transfer coefficient: www.pathways.cu.edu.eg/ec/Text-PDF/Part%20A-3.pdf
In other words, the IR radiative proportion is <<240 W/m^2 except for perfectly still air in which case most of the energy is absorbed in the air according to the Beer-Lambert Law. This event actually happens: it caused the phenomenon we call the mirage which is only stable for a flat surface with no wind.
So, what is the actual mechanism causing the IR to be <<240W/m^2? The answer is very simple. The air above the ground which is heated by convection is nearly at the same temperature as the Earth's surface. So, that air radiates heat to the air above it. Thus instead of assuming a vacuum with all the heat being emitted by radiation, then adding air at 1 atmosphere to absorb that energy and 'back radiate' it which is what climate science thinks, the radiation is set by whatever IR from the surface has penetrated the air unabsorbed, plus radiation from the heated air. This IR is then absorbed further up with the proportion of IR from the surface falling exponentially.
The key difference is that the emissivity of the air is much lower than that of the surface. Now you see why engineers use a composite heat transfer coefficient which varies with T1^4 - T2^4. They integrate all this by dimensionless numbers so the calculations can be made more easily. Climate science's explanation can only work with a vacuum near the ground! it's ludicrous.
Can you (or Russell) give a reference to any physics text that explains "thermal radiation involves the direct coupling of thermal emission states between emitter and absorber."
Or how thermal radiation is in any fundamental way different from radiation produced by a magnetron?
Feb 3, 2012 at 6:20 PM | Martin A
As you said before when failing to answer any questions yourself, your questions were directed at MDGNN.
Until he bothers to explain it to you yet again, I suggest you give this silly saga a bit of a rest.
OK - I take it you cannot. Any more than MDGNN could come up with a text that explains his unconventional views of radiation.
Oh dear, I didn't realise I'd cause all this trouble. top those who use the microwave concept, a microwave oven is very different from the radiative interchange between two materials. It is a cavity in which the metal surfaces cause standing waves to develop. The heating of the food etc. is because at the nodes the water molecules oscillate at high amplitude whereas at the antinodes, they are not forced into oscillation.
You can prove this by putting a big bar of chocolate on the base and turning on the unit. The nodes will melt. So, this is totally different from the uniform temperature you have on a solid surface. The concept of temperature assumes equilibrium and this is far from equilibrium. I once developed equipment to produce nano powders, a chemical reactor with wave guides - there it did reach equilibrium ~450°C as the MW energy was not a standing wave.
I've added a post top show how engineers look at combined convective plus radiative heat transfer. Remember, my previous discussion applies just to the radiative part of the heat transfer. This subject is not easy but the climate guys have simplified it to assuming just radiation. That is balderdash.
RKS: the definition of radiative heat transfer is the direct coupling of an emitter/absorber pair by radiation in line of sight so by definition, the IR density of states in both materials are coupled at the speed of light.
MDGNN
"I've added a post top show how engineers look at combined convective plus radiative heat transfer. "
How do we find it, please?
RKS: the definition of radiative heat transfer is the direct coupling of an emitter/absorber pair by radiation in line of sight so by definition, the IR density of states in both materials are coupled at the speed of light.
Feb 3, 2012 at 6:54 PM | mydogsgotnonose
I'm a little confused here.
Why are you directing this post at me, I've not questioned any of your answers to Martin etc.
OK - I take it you cannot. Any more than MDGNN could come up with a text that explains his unconventional views of radiation.
Feb 3, 2012 at 6:38 PM | Martin A
Please stop using troll tactics.
How about you answer questions put to you for a change.
Of course, trolls never answer questions.
<OK - I take it you cannot. Any more than MDGNN could come up with a text that explains his unconventional views of radiation.
Feb 3, 2012 at 6:38 PM | Martin A>
Looks like we're into some real science from Martin A at last.
So show us the textbook reason, in detail, why MDGNN's views on radiation are "unconventional"
It's not very easy, because MDGNN does not actually give any equations to make his brief statements precise.
But, for example, if I have understood him correctly, he says that radiation from a black body BB1 at temperature T1 is not absorbed whatsoever by a nearby black body BB2 at temperature T2, where T1 < T2.
Look at any chem engrg textbook dealing with heat transfer and it will explain that radiation from BB1 is absorbed by BB2 and at the same time radiation from BB2 is absorbed by BB1.
The net flow of power will be the difference between the two flows and will be given by a formula like q(T2^4 - T1^4).
If I have correctly understood what he says, then this is an example of how his understanding seems to differ from the standard view.
Why tack on provocative words like "troll", "mischief", "a big wind up going on here"?
I suggest just answering people's questions or pointing out errors or misconceptions in their answers. If, for some reason you don't like their approach, you can simply not respond.
Martin A. Let me explain in a different way. The S-B equation for a single body predicts the total radiant energy emitted by it for a particular temperature at its base emissivity, defined by radiation to space; no opposite radiation. When two bodies exchange radiation, it's possible that net exchange can become zero. Just ask yourself why this can happen? Think of the two parallel plate analogy.
One way of thinking about it is that the 'DLR' reduces the effective emissivity.
OK - I take it you cannot. Any more than MDGNN could come up with a text that explains his unconventional views of radiation.
Feb 3, 2012 at 6:38 PM | Martin A
The Dunning-Kruger is strong in this one. What to do ?
When the Dunning -Kruger effect is strongly in evidence, and the questioner's awareness of what photons get up to is too weak to allow of instruction by physical analogy, recourse to pidgin as a teaching aid may be justified. Let us suppose:
Science edukasin blong thisfella, him buggeremep verimas.
Thisfella, i go long littlefella skoolhaus techem pikininni byeanbye. Masta he mekem this fella pikininni studi bigfella integral blong Maxwell kanaka. Mana blong integral, i mekem thisfella savvy verimas teori blong quantum.
Then teory blong quantum, i mekem thisfells savy wiki wiki teori blong molecular radiation, then masta blong skoolhaus, he givem Martin bigfella examinasin. Thisfella im pasem, he go long bigefella skoolhaus, mekem kai kai bigfella book blong Pierrehumbert. Thisfella book mekem science education blong thisfella buggeremep small small finis,
You askem mebbe thisfella i no pasem bigfealla examinasin? Then im go long teachem cargo cult science blog belong Watts- reader blong there, i mekem alsaem pisin science wontok cargo cult science, Mekem thisfella Martin bigfella kanaka there !.
Teacherfella blong bigfella skoolhaus, im , i go long tekem vacasin longtime anyhow. Mebbe i go long getem bigfella grant fondation blong Koch Kanaka, mekem bigfella study climate impact when im not throw virgin in volcano byanby.
Savvy ?