Tuesday
Jan032012
by 
Bishop Hill
Bishop Hill Windy
Jan 3, 2012 Climate: Sceptics It has been very windy here this morning. My parents just telephoned to say they have just had next door's solar panels through their conservatory roof.
So end all who question the AGW consensus...
Reader Comments (181)
Fair treatment of potential impacts of a change in climate requires a balanced assessment of pros and cons of an increase in temperature contrasted with the corresponding pros and cons of a decrease in temperature. Past map exhibits of impacts appear to be dwell exclusively on negatives in a warming scenario and only serve to harden sceptical scorn.
"...Decided to carry on as normal as possible and made some toast ah! and there's the cat -- must have smelt the food." --Rick Bradford
Plucky, that, Rick. Are we downhearted? NOOO! Not while Britannia drools. Er, rules.
List of achievements on a post card please: Destruction of the economy and future stability of the UK.
"What a f....g shambles!" --Latimer Alder 'Tain't a shambles unless there's blood.
I shall not be purchasing toffee apples for the foreseeable future.
"OK I may need a thick skin sometimes, and more crucially I need to make sure I don't get tempted to spend all my time blogging, but hopefully dipping in from time to time will be useful!" -- Richard Betts
I think so. I'm certainly interested in anything you have to say on any subject.
This shows how fragile of a generating capacity this wind and solar nonsense is. You obviously have wind in the UK, we have a lot of that here in the US as well. We also have rather frequent hail, too, and some of it can be quite large (larger than the average orange, for example). Why install a generating capacity that is destroyed every time story weather breaks out? Hurricane Andrew in Florida damaged one smokestack of one unit of one conventional power plant. Had there been any significant wind/solar infrastructure there at the time, it would have been completely obliterated.
"...If solar is going anywhere then we can expect the prices amd [lack of] quality to have dropped dramatically in the next ten years, so I decided to hang on and buy them at £1500/ installation, with a saving of 50%/annum when they've refined the technology." --geronimo
That's a big IF. And solar cells are not new technology, so the refinement has largely been accomplished years ago. There are persistent stories being spouted by green fictionists that new solar cells with higher efficiency and lower cost are just around the corner. Well, they're not. Economy of scale doesn't work when most of the cost of a product is materials, not overhead costs. If anything, the cost of the materials may go up due to inflation, not down due to refined technology.
@Richard Betts
I hope I can state with confidence that many here who do not comment often (or at all) are grateful for your efforts to communicate your views. I for one am glad simply to be able to read and reflect upon your remarks in the stream of all the information I am trying to absorb daily. I can't add much to most of the discussion here -- I'm simply a (US) citizen seeking to understand all the policy issues and options better.
Jan 3, 2012 at 11:49 PM | Richard Betts
"I don't think we can see an effect on disasters yet". Why add the alarmist "yet"?
"I don't think we can see an effect on disasters" would have been much more objective.
Richard Betts
Do you know who write these noddy words in the Met Office FAQs
Do you know who in the Met Office write this type of nonsense (I assume you wouldn't accept what is said here)? I know you are a physicist, so isn't it possible for somebody like you to write these answers with a bit of the physics explained correctly?
I suspect these answers are for propaganda purposes. Teachers and others who do not understand physics can point to the Met Office and use nonsense such as this.
Since when have "greenhouse gases" stopped energy being transmitted back into space?
Do you know who the "scientists" are who have the beliefs given in the 2nd paragraph? Are they of a religious nature?
I agree that the problem really is those "scientists" who hold that belief and have transmitted that belief to politicians and greens with the voice of misplaced authority and use of the word "consensus".
The Met Office is as bad as the green NGOs in its propaganda work.
Philip
Your question at 07:15 AM and mine at 10:57 PM are essentially the same: when we do get a plain English explanation of the CO2 -> warming hypothesis it is invariably gobbledegook. In addition, the fact that incoming heat as infra-red would be partly intercepted and re-radiated to space, CO2 -> cooling, is not included. It is difficult to conclude other than negatively on the motives/understanding of the institutions publishing such tripe.
Re: Jan 3, 2012 at 3:50 PM | Justice4Rinka
That "chain reaction" article is an interesting find. "What sounds now like wild ecotopian fantasy will have turned into an unexceptionable statute governing daily life." This has actually happened, although of course it still hasn't changed from being ecotopian fantasy ten years on, it just manages to be dull EU legislation at the same time.
"Mayer's brother Ellis was president of the Flat Earth Society - not because he thought the earth was flat, but because he believed that conventional wisdom should always be challenged. Freethinking Mayer clearly subscribes to this, too. If he has his way, in a decade or thereabouts, so shall we all."
Except, of course that "green commonplaces" are now the conventional wisdom, and the last thing that Hillman's successors want to do is challenge it.
@Jamspid - apologies, I snipped both your (repeated) comments by mistake- please re-enter one!
simpleseekeraftertruth Jan 3, 2012 at 10:57 PM
I don't think radiation in the Earth's atmosphere is a direct analogy to an electric current in a resistor.
But, to attempt an answer to your question, the atmosphere is largely transparent to the incoming radiation from the sun, which is largely in the visible wavelengths. The outgoing radiation from the ground is long wavelength infra-red which is absorbed (and then promptly re-radiated) by water vapour (and also by trace gases such as CO2, CH4). So the behaviour does change with orientation.
[Unlike some respected commenters on BH, I see no paradox in the warmer ground absorbing radiation emitted from water (or CO2) molecules in the cooler atmosphere. The ground absorbs an incoming photon of IR irrespective of the temperature of the entity that omitted it. Photons do not carry labels stating the temperature of the body from which they were emitted. ]
Richard Betts: "...the 2003 European heatwave is estimated to now be twice as likely due to anthropogenic climate change"
Now there you go, one doesn't have to have more than a nodding acquaintance with the scientific method and the ecosphere to see that this assertion is total nonsense. And I know where it came from, it came from computer simulations, right? These simulations were run by people with an undying belief that humans are causing the planet to warm and that there will be disastrous consequences, right?
I'd even bet that those same computers were the ones that gave us the yellow alert the day before a red alert, and that told us there was volcanic ash in the atmosphere over the Atlantic when there wasn't.
Martin A
Thank you for your response and yes I do understand cooler objects emitting which can be easily observed by photographing a cool object with a (warm) infra-red camera. However, as the sun emits full-spectrum radiation, the explanations we see such as that of the Met Office which Philip Bratby mentions, fall short of full. Leaving aside analogies such as the successive coats of paint on a pane of glass and others equally unhelpful that AGW theorists use, one would expect that in 20years or more a succinct explanation would have been composed that includes all of the basic events which occur when a planet with a *greenhouse* atmosphere intercepts solar radiation. If one was to exist it could be used by the likes of the MO which currently attempt and then fail to explain the phenomenon.
"long wavelength infra-red"
But there's plenty of that incoming from the Sun, too, which presumably gets attenuated, so isn't the net result about the same?
Martin A. "[Unlike some respected commenters on BH, I see no paradox in the warmer ground absorbing radiation emitted from water (or CO2) molecules in the cooler atmosphere. The ground absorbs an incoming photon of IR irrespective of the temperature of the entity that omitted it. Photons do not carry labels stating the temperature of the body from which they were emitted. ]"
I am showing my ignorance here, but have pondered for a long time as to how the ghg works. It's not like a greenhouse that's for sure, ir is absorbed by C0,2 mainly in the 15nm range. This presumably raises the energy state of the molecule which then re-emits the energy by releasing a photon or photons. Don't the laws of physics mean that the energy released can now only travel towards a body with a lower energy state? Since the energy itself has been released by the earth which is in a higher energy state than the atmosphere, how is the energy moved from the molecule of CO2 towards the earth?
Coniston
IIRC, there was a 'fact or fiction' quiz on the Science Museum website a couple of years ago, in support of their ill-judged 'Prove It' campaign:
Link
It's gone now, I think, but they do have this, which contains more disinformation that you can shake a toffee apple at:
Link
They also seem to bought a new logo from the same people who did the Olympic one...
Continuing on this off-topic thread...
James P at 9:38 AM, Martin A at 8:43 AM is basically right. The light from the sun is mainly UV and visible light - there is long wavelength IR, but not much, due to the fact that the sun is very hot & hence it emits mainly shorter wavelength radiation. So much of the incoming solar radiation reaches the surface (not all - some is reflected by things like clouds, and some is absorbed in the atmosphere).
geronimo at 9:41 am, one way to think about the fate of IR photons emitted at the surface of the earth is that they undergo a random walk: they get emitted from the surface, then absorbed by a molecule in the atmosphere. This then reemits a photon in essentially a random direction - up, down or sideways. The photon can then either return to the surface, or it can go higher in the atmosphere. At some limiting altitude, the probability that a photon emitted upwards will be reabsorbed becomes quite low, and the photon continues into space.
Philip Bratby at 7:15, I accept that what you quote there from the Met Office is simplistic, but is it really completely wrong? What I have just written above is simplistic also, e.g. because it leaves out the role of convection in moving heat around in the atmosphere, but I don't think it is completely wrong.
There's been quite a few comments recently by mydogsgotnonose and others who appear to dispute some of what I wrote above. I'm with people like mooloo that it would helpful if mydog could explain his ideas more fully, because to be frank, though he has been posting them for some time, I do not understand what he is claiming. "Back-radiation" clearly does exist - photons can be emitted in any direction, and as Martin A says, they have no memory of the temperature of the region they were emitted from, so they can end up being absorbed in a region with a higher temperature. Equally, it is true that the statistics of absorption and emission must be such that they obey the laws of thermodynamics, so that there cannot be net transfer of energy from lower to higher temperatures. But it does not appear to me that even the evil Met Office ;-) is claiming that there is such a net transfer. As said above, the net flow of heat in the consensus picture is from the surface of the earth into the atmosphere and then into space. This emission of heat from the surface is "powered" by the shorter wavelength light that comes from the sun to the surface of the earth - the atmosphere as a whole is very far from being at thermal equilibrium. It would really help if mydog could explain where he or she disagrees with this.
For what it is worth, Roy Spencer (not the world's most famous consensus-follower ;-) ) has a long post about understanding the basic physics of the greenhouse effect. One pertinent quote:
Jeremy,
My understanding of the radiative physics is the same as yours (while allowing for the proper integration of solar radiation over the illuminated side of the planet). Of course, we also need to account for conduction, convection, phase changes, ....etc.
I also think that the term "greenhouse effect" means very different things to different people, and should be dropped as it is a misnomer for atmospheric physics effects.
Reply to Jeremy Harvey.: I do not claim that 'back radiation', defined as IR radiation scattered or thermally emitted from the atmosphere cannot be measured by a radiometer pointing upwards, downwards or sideways. However, I do claim that when the atmosphere is at a lower temperature than the Earth and is in radiative line of sight, that radiation when absorbed at the earth's surface can do thermodynamic work.
This is physics, not hand waving or touchy-feely soft-Marxist climate science as expressed by people who think they know much more than they really comprehend [no offence meant!].
I'm indebted here to a post on Spencer's blog by Christopher Game: http://www.drroyspencer.com/2011/12/why-atmospheric-pressure-cannot-explain-the-elevated-surface-temperature-of-the-earth/
'The basic physical idea was first clearly set out by Pierre Prevost in 1791. He took the view that heat rays pass through each other without interacting, and we still accept that profoundly importantly view today. That is the reason why the idea of net flux is used.
Prevost also made it clear that every body emits heat radiation completely determined by only the internal state of its material constitution, including its material temperature if such exists, and absorbs radiation so emitted from other bodies. This is known as Prevost’s exchange principle.'
Prevost stated that two bodies are in radiative exchange equilibrium just when the radiation emitted by each and absorbed by the other exactly balances the reverse limb of the exchange.....
If two bodies have different respective definite temperatures, then the hotter will overall heat the colder, by Prevost’s radiative exchange,
He then goes onto Eigen values of rate matrices; we'll skip that. The essence is that there can be no net heating of a hotter body by a cooler body.
Thus the Trenberth diagram showing 'back radiation' is fundamentally wrong because it assumes that that part of the IR energy scattered by GHGs towards the Earth’s surface is an energy source, heats the Earth’s surface thus creating more IR emission, in turn more back radiation, extreme positive feedback.
Expressing why this is wrong is clearly testing even professional physicists far more knowledgeable than me, a humble engineering genius, but I’ll give it a go….
It’s all tied up with the IR density of states and the Law of Equipartition of Energy. For every body, whether gas liquid or solid, there is equilibrium between the average kinetic energy of the molecules and the proportion of the molecules which are sufficiently excited thermally to be able to emit IR photons. Where there are many degrees of freedom, it can be complex maths.
What this means is that when an IR photon is absorbed, it is perfectly possible that almost immediately an IR photon of the same energy is emitted thus ensuring there is no thermalisation of the energy, no conversion of that extra IR quantum to heat, the principle of thermodynamic work.
It must be very confusing for people taught soft sciences like environmental or climate science without the necessary depth of physics, yet have access to modern instrumentation, that when you spectrally resolve ‘back radiation’ from a clear sky, it shows the IR emission lines of GHGs, yet that does not mean that energy can do thermodynamic work.
Let me explain my interpretation which owes nothing to any textbook but does owe its thinking to the greats of physics. At radiative equilibrium, Kirchhoff’s law of radiation states that emissivity = absorptivity. This means the rate of change of kinetic energy of the material to IR energy does not change with time. So, the density of IR emitting states is the same as the density of IR absorbing states.
[Assuming the IR detector is near the earth’s surface] those IR quanta you see in the emission spectrum of the ‘back radiation’ from the atmosphere hit the Earth’s surface, are absorbed in the absorption IR density of states and are instantly replaced by quanta in the opposite direction from the existing emission IR density of states so no thermodynamic work, no change of average kinetic energy.
Curry has been converted from the dark side. Spencer is on his way. In time the rest of oxymoronic climate science will realise that its fondly held, warm, cuddly belief in their moral superiority, the great Arrhenius Back Radiation Hypothesis, is bunkum and CO2-AGW is much lower than claimed. But I could be wrong, not for the first time.
PS: last but one paragraph: this implies that the IR quanta emitted by the Earth's surface are of exactly the same energy distribution as the quanta received. This is an extraordinarily important physical principle implying real time communication at the velocity of light between emitter and absorber of the density of states.
The truly great physicists know this and express it in great equations. However these mean nothing to practical people unless someone approaching normality can express it in real world terms.
PPS Second sentence of the main reply:
However, I do claim that when the atmosphere is at a lower temperature than the Earth and is in radiative line of sight, that radiation when absorbed at the earth's surface can do no thermodynamic work.
mydogsgotnonose, thanks for your reply. But I'm still struggling to understand exactly how you disagree with me, Curry, Spencer or indeed the consensus. As I wrote, "the statistics of absorption and emission must be such that they obey the laws of thermodynamics, so that there cannot be net transfer of energy from lower to higher temperatures". That is kind of the same as you wrote above, when you wrote "I do claim that when the atmosphere is at a lower temperature than the Earth and is in radiative line of sight, that radiation when absorbed at the earth's surface can[not] do thermodynamic work" (I added the 'not' in square brackets). But it is also, as I understand, what people like Trenberth claim. To make this discussion slightly more quantitative, let's pick (pretty much at random) one version of the energy budget diagram. I googled "Trenberth Earth's Energy Budget Diagram", and found e.g. this picture, which seems to me to respect the thermodynamic constraint you mention: there is no net work carried out by the cooler atmosphere on the earth's surface, because the rate of energy loss due to radiation by the surface (350 W/m2) is greater than the rate of back-radiation (324 W/m2).
I continue to think that it is helpful to have a hierarchy of doubt about the IPCC consensus - anything claimed there may be wrong (after all, I might just be a brain in a vat), but some things are more likely to be wrong than others. The idea that there is an energy budget, in which back-radiation plays some role, doesn't strike me as one of the most doubtable things about the consensus (the role of clouds and aerosol seems to me to be a much more fruitful area for doubt). Though I'm happy to accept that I may have misunderstood something.
Jeremy Harvey: they claim the back radiation is absorbed [thermalised = converted into thermodynamic work] by the surface also that all the IR energy from the surface is thermalised.
In my opinion, they've got it mostly wrong. I'll accept some thermalisation of IR by the atmosphere. In 1993, the US' best IR physicist, Will Happer, walked away from his science advisor job with Gore because he wasn't going to prostitute his science for politics.
Climate science has adopted a far too simplistic view of the physics but the strains were hidden by the fast warming of the 1990s. Now we have Hansen claiming about 50% increase of net AIE and extra ocean cooling to explain constant temperatures thereby keeping his view of 4.2 K CO2 climate sensitivity alive. Thus there is no null hypothesis.
The real experimental proof of what I am claiming was early last year [sorry no URL] when a Dutch student shinned up an 800 foot radio mast and found at night that the up-down IR signal fell exponentially with height, what you should expect for Beer's Law.
Nahle is working on Cp data which has built in the 13 and 15 micron IR bands of CO2 as Cp changes by 13.1 % from 250 to 350 K. The detailed effects include the van de Waals interactions and these change. Also you have IR band saturation near the earth's surface and this leads to self-absorption.
This can lead to an incremental fall of emissivity and absorptivity facing the emitter as CO2 increases.
This area of research is just developing. The fact that it has been ignored since 1993 is quite significant.
PS the Dutch work was exponentially decreasing to zero, which is what you'd expect for an isothermal atmosphere with no net IR transport until you get appreciable atmospheric temperature gradient.
PPS I believe i have also solved the key problem with the aerosol optical physics! that is badly wrong too and since 2004 has been outright deception by NASA.
simpleseekeraftertruth Jan 4, 2012 at 9:38 AM
All the explanations I have seen seem (to me) over-simplified, qualitative only and unconvincing. Judith Currie, on her website, stated that there does not seem to be a convincing graduate-level explanation (ie intermediate between simplified hand-waving explanations and complicated computer models). I find it utterly amazing that such an explanation seems to be unavailable.
James P Jan 4, 2012 at 9:38 AM
Yes, there is plenty of long wavelength IR that comes from the sun. It radiates many orders of magnitude more power in the long wavelength range than the earth does.
But, because the sun's v. hot, its radiation peaks at a much shorter wavelength, so the long wavelength IR from the sun contains negligible power relative to the shorter wavelengths from the sun.
For practical purposes, the radiation from the earth and from the sun lie in different wavelength ranges that do not overlap.
["..99% of solar radiation incident on the top of the earth's atmosphere is accounted for by the UV, visible, and near IR bands together." (wavelengths from 0.1 micro m to 4 micro m).
Over 99% of the energy emitted by the earth and atmosphere is found in the thermal IR band from 4 micro m to 100 micro m."
(p65, A First Course in Atmospheric Radiation, 2006, Grant W. Petty ]
geronimo Jan 4, 2012 at 9:41 AM
A hot body (whether a sun, a planet or a CO2 molecule) emits photons without asking what is going to happen to them later. The photons travel through empty space not knowing what (if anything) they are going to hit. A photon that collides with a body does so without first asking whether the body is hotter or cooler than the body that emitted it.
Of course, if you put a hot body next to a cool one of the same size, the net energy flow will be from the hotter one to the cooler. That is assured because the hotter one emits photons at a higher rate, and with more energy per photon, on average. Even so, there will be photons from the cooler one arriving at the warmer one - this is entirely consistent with the laws of physics.
Richard Betts Jan 3, 2012 at 11:42 PM
Chapeau!
Yes I do think there is a human influence on climate in terms of the long-term averages
Richard
There you go again. What you say here is possible, of course it is, but where's the evidence (empirical and measured). Answer, there isn't any., is there.? Is there even any proof at all that the rise in temperature from 1975 to 1999 is even provably unprecedented. How much of 0.7 - 0.9°C in 100 yrs is human and how in heavens name can you separate the many climate influences and Is global temp valid, and on and on and on. As has been pointed out in many posts here, the Met Off website is full of agw nonsense and myth re-enforcing drivel.
And then you do the classic and resort to models. Let me just say "reliability of models financial or otherwise" ?????
Please persuade your colleagues to take down the PR rubbish from your site and replace it with science, real science.
Even so, there will be photons from the cooler one arriving at the warmer one - this is entirely consistent with the laws of physics.
But the probability that they will be absorped is negligable. The rest is absolutely correct as we understand it at the moment.
Jan 4, 2012 at 12:33 AM | Pharos
I completely agree, see this paper and also this one by my team and I which are quite clear about there being pros as well as cons of warming and/or increased CO2 concentration for food and water resources.
Jan 4, 2012 at 12:55 PM | Martin A
Thank you!
Stephen Richards Jan 4, 2012 at 1:04 PM
Do they bounce off or do they wizz straight through? ;)
Jan 4, 2012 at 6:34 AM | simon abingdon
Hi Simon,
I disagree. I don't think including "yet" is alarmist, and I don't think missing it out is objective. We have good reason to think that changes are taking place and that further change may take place in the future, so closing off the sentence by saying that what we've seen in the past is the end of the matter is incomplete.
Incidentally, please can we drop this whole tedious "you work at the Met Office and contribute to IPCC so therefore you must be an alarmist" line? If I was an alarmist then I wouldn't fall foul of people like Joe Romm when I say things that are scientifically correct but happen to be off-message as far as they are concerned.
I do think anthropogenic climate change exists and needs to be take seriously, but I also know there are large uncertainties in the rate and magnitude of future impacts, and that these may be positive as well as negative. I also think that anthropogenic climate change is merely one aspect of climate science, and that understanding all aspects are important. I further think that it is worthwhile to attempt to make forecasts of the future, even though current models do of course have significant limitations. One of the reasons for improving our understanding and attempting to make forecasts of the future is to help us live with variations and changes in climate, whether occurring entirely naturally or being modified further by human influence. I don't think this is "alarmist".
Judith Curry has some guidelines for etiquette on her blog, and one of these is:
I think we could have a much more constructive conversation if words like "alarmist" were not used. I never use "denier"!
Cheers,
Richard
Jan 4, 2012 at 9:32 AM | geronimo
Hi geronimo
I take your point, but unless one simply assumes that there has been no human influence on climate at all (which I am told very few people, even sceptics, believe) then how else do we go about estimating whether we've changed the risk of extreme events?
Having said that, I did miss out a confidence statement - I should have said "it is estimated with 90% confidence that European heatwaves such as that seen in 2003 are now be twice as likely due to anthropogenic climate change".
Martin A Jan 4, 2012 at 12:36 PM
"I find it utterly amazing that such an explanation seems to be unavailable."
Quite, and that is why I search for an explanation based on all flux and spectra with modifiers to those considered fully when in a state of equilibrium. We have a plain English explanation of the general theory of relativity and of how a self-propelled mechanism can escape the clutches of gravity - rocket science - but not one about the most important question of today that directly impacts the lives of everyone.
If I may be so bold I will kick-off one with this (please note that I am not an advocate for GHG theory, merely that which my name suggests);
Solar radiation impinging on the Earth's atmosphere is partly reflected back to space by components of that atmosphere. We call those components *greenhouse* gasses for want of a better terminology.
Next sentence anyone?
Martin A: 'Do they bounce off or do they wizz straight through? ;)'
What climate science doesn't seem to have realised is that photons scattered by GHGs back to the Earth's surface are re-scattered from that surface thus in effect forming a standing wave.
There is no necessary thermalisation at the Earth's surface or by the GHGs.
This consequence of the Laws of Radiation which uniquely, climate science seeks to revoke with no experimental evidence! So no climate model can predict climate.
simpleseekeraftertruth Jan 4, 2012 at 1:53 PM
(I think it is mainly clouds that result in the majority of the direct reflection, not the greenhouse gases)Neglecting a very small proportion directly absorbed by the atmosphere or reflected directly by the ground, the remainder is absorbed by the surface of the earth or the oceans.
Re:
[Unlike some respected commenters on BH, I see no paradox in the warmer ground absorbing radiation emitted from water (or CO2) molecules in the cooler atmosphere. The ground absorbs an incoming photon of IR irrespective of the temperature of the entity that omitted it. Photons do not carry labels stating the temperature of the body from which they were emitted. ]
Jan 4, 2012 at 8:43 AM | Unregistered Commenter Martin A
... as Martin A says, they have no memory of the temperature of the region they were emitted from, so they can end up being absorbed in a region with a higher temperature...
Jan 4, 2012 at 10:05 AM | Unregistered Commenter Jeremy Harvey
The following:
Simple Math/Physics: c = fl; l = f/c; f = l/c.
Photons do carry a label (in Bold Letters; not fine print) stating the temperature of the body from which they were emitted! The label is the frequency/wave-length of the photon. In fact, it is how we estimate temperatures remotely.
I have no problem (tentatively) accepting that a body will not thermalize recieved photons which are at lower frequency than the body's current emitting frequency (temperature), but merely reflect or re-emit the recieved photons. Assuming otherwise does seem a paradox to me. I'm not sure that this "intuition" is completely supported/explained by the latest Quantum-Physics Theories, but it is consistent with classical thermodynamics and seems a good working hypothesis until contrary data (vs. conjecture/computer-model) indicates otherwise.
I carry coffee to work in a thermos bottle, not a glass jar. The jar would have my coffee at room temperature before I got to work, while the thermos keeps it hot 'til lunch. Intuition (again) seems to indicate that radiative heat loss (while certainly real) is strictly a second-order effect as compared to the first-order effect of conduction/convection.
So, until convincing expirimental/observational data (and some supporting theory) shows up, I consider the heating by back-radiation conjecture to be questionable, and if it does in fact exist, of marginal effect.
Martin A
Clouds do come next but the first encountered impedance to the flux is partial absorption and scattering. In a full explanation, that point cannot be omitted as minor at this stage even though it could possibly be shown as such later on as an explanation develops.
mydogsgotnonose Jan 4, 2012 at 1:56 PM
Well, I'd be the last one to stand up and be counted with the "climate scientists". And I'm sorry to have to declare my ignorance of what "necessary thermalisation" means.
But I am pretty sure that, when a photon arrives at a black body, it does not stop for a moment and say:
"Hold on. What's your temperature? OK. Let me check my note of the temperature of the body that emitted me. Oh - oh! According to my records, you are cooler than the body that emitted me. Golly, I've just remembered that my library books are due back today. Sorry, I can't hang around all day long. Tootle-oo!"
My recollection is that a black body (because this is what black bodies do) absorbs each and every photon that comes its way, irrespective of the origin of the photon. And irrespective of the temperature of the black body itself. Each photon absorbed raises the black body's temperature a tiny degree.
Of course, for a black body in thermal equilibrium with its surroundings, it's also busy emitting photons.
Each photon emitted lowers its temperature a miniscule amount. Overall it emits photons, at a rate, and with mean energy, that equals the mean rate it is absorbing energy.
Jan 4, 2012 at 1:37 PM | Richard Betts
"One of the reasons for improving our understanding and attempting to make forecasts of the future is to help us live with variations and changes in climate, whether occurring entirely naturally or being modified further by human influence."
Unfortunately, the results to date of attempts to make forecasts of the future were accepted as "facts" by those who rule over us and we can now see the outcome in the UK as ageing proper dispatchable power stations inexorably drop out of the mix only to be replaced by ever increasing numbers of intermittent sources of electricity.
The effect of the acceptance of these "facts" has been for governments to boldly interfere in the design and specification of reliable, efficient generators of electricity and has also caused the elimination of coal as a fuel for electricity generation.
There is no question that the single most important commodity to the UK to "help us live with variations and changes in climate" is the provision of a cheap, reliable supply of electricity delivered to the 26 million domestic electricity meters, day and night.
In this way, if it gets too hot in our homes we can cool ourselves down or, if it get too cold in our homes we can heat ourselves up.
This is what used to happen in the UK between 1948 and 1990.
However, it is possible to imagine where the UK would be now had it not been for the triple whammy in the 1990s of ditching the Central Electricity Generating Board, the rise of "man made global warming as a threat to the planet" and the concept of "man's carbon footprint".
The UK electricity supply system would now be comprised of a set of despatchable power stations, none over the age of 35 years, probably made up of 25GW of coal-fired units, 25GW nuclear and 25GW CCGT. There would also be in place a rolling programme of replacement power stations under construction to cope with older power stations reaching retirement at age 35 years.
Now, the only despatchable power stations being built is about 4GW of CCGTs, and the pace is not matching the loss of coal-fired and nuclear power stations and we are also seeing the loss of CCGT capacity.
This is the fault of all MPs (blue, red and wishy-washy) in the first instance, and they must be punished, but there also has to come a time when the advisors who pushed this lunacy (or sat on their hands and kept schtum) must be made to face the same consequences.
dadgervais Jan 4, 2012 at 2:40 PM
Yes, of course, the wavelength/energy of a photon is a useful general clue as to the temperature of the body that emitted it. But it's only a clue - the wavelengths the photons from a body at a given temperature will fall in a a pretty wide range (ten to one for 90% of them - just from memory).
It's only after you have measured the energy of a respectable number of photons that you know the temperature of the emitting body with any precision.
Don't get me wrong. I think that the absence of a reasonably simple quantitative model for the greenhouse effect is itself a very strong indictment that there is something very dodgy about the greenhouse hypothesis. Until I see a model that can be described and analysed on say two sheets of paper - and one that you can put numbers in and get numbers out - it is just hand-waving so far as I am concerned and totally unconvincing.
But saying that a photons emitted from a body at one temperature cannot be absorbed by another at a higher temperature conflicts with my understanding of how the universe works. In pointing this out, I'm by no means saying that I think all is well with the greenhouse hypothesis.
Martin A. What I am trying to do is to think out the radiation physics which has been forgotten by most scientists, including perhaps me.
There is a missing subtlety here I haven't yet explained. You are right that each and every arriving photon is absorbed and at equal emitter and absorber temperature, as many are re-emitted. Then we have the law of Equipartition of Energy which means that re-emission is almost instantaneous from an already IR excited molecule so there is no thermalisation.
However, imagine that the atmosphere suddenly falls in temperature. The emission rate of IR photons from the gas immediately falls because the density of such states also falls. Thus fewer IR photons arrive at the emitter. This triggers a change to higher emissivity of the emitter because for the temperature there are fewer filled emitter states so more thermal energy is put into those states.
Thus Prevost Exchange Energy is not a passive effect, but a means for the two materials to adapt to changing circumstances.
The original Spencer reference quotes the action of a third emitter which can modulate the heat transfer between the other two and the possibility this could give high positive feedback. This is the principle of the Thermal Valve.
This physics is far more subtle.than climate science even imagines it could be.so no wonder they've got it badly wrong.
Jan 4, 2012 at 3:23 PM | Unregistered Commenter Martin A
If I understand correctly, (and as an oldster, I may no longer do) the spectrum is a result of random variation of energy content of the individual particles (which probabalistically trend toward but never achieve uniformity) and the random motion of the particles themselves, with some moving toward and others moving away at the instant of emission, there must be a doppler spreading of observed frequency/wave-length. If all particles were identical, had the same energy content, and uniform velocity (including direction) we would perceive a single frequency spectral line.
It's called a laser!
MDGNN
How far does the earth approximate to a black body? There are roughly three sorts of surface; ocean, rock/sand and vegetation (grassland and forest).
Here's a conundrum, has anyone been in the desert during the night? If you have you will notice that the night time temperature goes from a pleasant 40C to extremely effing cold. While in the tropical and sub-tropical climes night time temperatures vary between a few degrees below the day time temperatures.
Again, I'm showing my ignorance, but there appear to be two things in play here, one is that the CO2 in the atmosphere has no reason to be different above the deserts and the tropical regions that I know of, and the second is that the water vapour is missing from the desert region and in abundance in the tropics and sub-tropics. This, at first blush, would suggest that (1) there is back radiation (2) it is caused by GHGs and (3) that CO2 is having very little impact on the back radiation.
If someone can help me out of my confusion and tell me what's wrong I'd much appreciate it.
Jan 4, 2012 at 4:51 PM | Unregistered Commenter mydogsgotnonose
Got a chuckle out of me. Thanks mate.
P.S. To my horror, i must correct myself. Of course it should have been:
c = fl; l = c/f; f = c/l. Even we OCD individuals can sometimes overlook a detail.
Can't believe I was first to catch it. Perhaps BH regulars were just too polite to call me on it.