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Discussion > Simon Abingdon/Jonathan Jones/Radiative transfer

Ultimately, of course they would emit until they reached the temperature of the initie void, i.e. as close to zero as zero-point energy will allow.

May 1, 2012 at 4:00 PM | Unregistered CommenterTheBigYinJames

What happens when the heater is switched off will rather depend on the heat capacities of the two discs but in principle it will be the passive disc that is the first to reach zero. The now unheated disc can only lose heat to the passive disc and therefore cannot reach zero until the passive disc gets there.

May 1, 2012 at 7:20 PM | Unregistered CommenterJorge

May 1, 2012 at 7:20 PM | Jorge

Thank you very much.

May 1, 2012 at 9:15 PM | Unregistered CommenterBrownedoff

Being pedantic in such matters I'd say that neither disk ever actually reaches zero temp but both asymptotically approach zero, the passive disk always being somewhat closer to zero than the no-longer heated disk with the heater attached.

[Of course, it's a model, an idealisation.]

May 1, 2012 at 9:35 PM | Registered CommenterMartin A

RKS
Can I join you in asking for somebody to take a step away from theoretical physics and give some inkling of what happens in a real world which is not a black body, is surrounded by an atmosphere, and whose primary heat source is an outside body (let's call it the sun)?
The original purpose of this discussion was fine and I learnt from it but why is everybody so reluctant to address the situation that we actually face? Why will no-one explain to us benighted ones what is really going on?

May 2, 2012 at 6:50 PM | Registered CommenterMike Jackson

RKS
Can I join you in asking for somebody to take a step away from theoretical physics and give some inkling of what happens in a real world which is not a black body, is surrounded by an atmosphere, and whose primary heat source is an outside body (let's call it the sun)?
The original purpose of this discussion was fine and I learnt from it but why is everybody so reluctant to address the situation that we actually face? Why will no-one explain to us benighted ones what is really going on?

May 2, 2012 at 6:50 PM | Mike Jackson>>>>>>>>

Many thanks Mike.

I was beginning to feel I was the only person contributing to the BH blog who was mainly interested in the workings of the REAL world.

regards,

May 2, 2012 at 9:59 PM | Unregistered CommenterRKS

I think the reason for the "theoretical" discussion of back-radiation was because of MDGNN continually claiming there's a fundamental problem with the basic theory... not some effect of the complexity of the system. So the discussion was to show the theoretic basis of back-radiation as a concept.

It could be in practice (and Jonathan Jones would be the first to say this) that other effects in the real system, such as convection, could completely obliterate back-radiation in the real atmosphere - but that doesn't mean it isn't happening.

May 3, 2012 at 8:25 AM | Unregistered CommenterTheBigYinJames

I think the reason for the "theoretical" discussion of back-radiation was because of MDGNN continually claiming there's a fundamental problem with the basic theory... not some effect of the complexity of the system. So the discussion was to show the theoretic basis of back-radiation as a concept.

It could be in practice (and Jonathan Jones would be the first to say this) that other effects in the real system, such as convection, could completely obliterate back-radiation in the real atmosphere - but that doesn't mean it isn't happening.

May 3, 2012 at 8:25 AM | TheBigYinJames>>>>

A noble cause no doubt, but as an old engineer I cannot see how, in a steady state non pulsating system, it is possible for the energy flux in any part of the system can be greater than the energy supplied to the system i.e Watts.

Of course, I don't dispute that some small proportion of the multi directional emitted radiation from the back radiating source is directed back at the original source of excitation.

If the discussion can provide a description of the interaction between the two sources of radiation I would indeed be interested.

What irks me a little is that I have asked on a few occasions, and even started a slightly humourous thread, for a discussion of the actual effect of back radiation at various levels of emissivity, with not one single response. Not even to rubbish my post.

There are sound reasons for the extra warmth of the Earth due to the presence of an atmosphere - And the role of CO2, causing rapid distribution of heat throughout the atmosphere and thence to space, is as a source of cooling.

Best of luck with your project.

May 3, 2012 at 9:09 AM | Unregistered CommenterRKS

BigYin
I think you're right about where this discussion started and, as I said, I found Jonathan's seminar very informative and useful. But only as a theoretical exercise and I'm not sure that mgnn's point was about the theory.
The thing is that earth is not a black body, nor is it a disc, nor is it surrounded by a vacuum (well, it is, but there's an atmosphere in the way!), and nor is it its own primary heat generator. But nobody seems able to agree on how the laws of thermodynamics work in that situation and — surrounded as we are on this site by scientists and engineers — when RKS or Rhoda or I ask for a lesson on the real-world effects of radiation the result is a deathly silence. As RKS says, not even a posting telling us we're talking crap!
My second question which follows from my first is: if everybody is so ignorant of the actual effects (which I assume is the case or they'd be only too pleased to demonstrate their knowledge and make a fortune!) how come we have been led by the nose down a path that is costing the earth and possibly will cause worldwide havoc when finally nature herself provides the answer?
Or is CAGW actually a reality in the making after all?
Meanwhile, though I agree that mydog gets a bit tedious on occasion I'm still keeping faith with him because (a) he sounds as if he knows what he's talking about; (b) I have more faith in engineers and technicians than I do in scientists when it comes to describing the real world.

May 3, 2012 at 11:49 AM | Registered CommenterMike Jackson

Or is CAGW actually a reality in the making after all?
Meanwhile, though I agree that mydog gets a bit tedious on occasion I'm still keeping faith with him because (a) he sounds as if he knows what he's talking about; (b) I have more faith in engineers and technicians than I do in scientists when it comes to describing the real world.

May 3, 2012 at 11:49 AM | Mike Jackson>>>>

Oddly enough, Ned Nikolov has suggested his theory on the effects of atmospheric pressure and insolation would be far better understood by engineers than by climate scientists, who's minds had been prejudiced by years of indoctrination in radiative physics.

I think we can now understand mydog's frustration in his attempts to get his message over, when all we get is incessant wittering on about back radiation and an absolute refusal to discuss other real drivers of climate.

The discussion of science at BH recently seems to have become very one sided.

I sometimes wonder if some of our contributors are really closet warmists wearing sceptic hats.

May 3, 2012 at 12:36 PM | Unregistered CommenterRKS

Mike Jackson:

Meanwhile, though I agree that mydog gets a bit tedious on occasion I'm still keeping faith with him because (a) he sounds as if he knows what he's talking about; (b) I have more faith in engineers and technicians than I do in scientists when it comes to describing the real world.

There are so many things that seem either wrong or ill-judged in the reasoning in this final paragraph that it's hard to know where to begin.

First up, you imply that you know that mdog is an engineer or a technician. Would it in any way strengthen your belief in this regard if he was to show us a CV? If not I wonder what makes me so different from some others on this blog. It would sure make a difference to me.

Second, if nobody knows how the atmosphere works that is hardly a reason to 'keep faith' (strange and disturbing phrase in the context) with someone who has studied it, by his own account, for a very short amount of time.

Third "he sounds as if he knows what he's talking about." He doesn't to me. Even an Oxford professor of physics had to admit he found mdog very hard to understand. My experience is that if someone really knows that they're talking about they can explain it in way that makes sense to others. And when mydog was in effect challenged by this thread I thought his reaction was abysmal, insulting those involved, pouring scorn on modern science as a whole and finally coming to the thread and talking nonsense that he was unable or unwilling to explain. And when mdog finally says something that is easy to understand and is challenged on it, as I did with his "rapidly evolving consensus from objective scientists is that real CO2 climate sensitivity cannot be more than ~0.3 - 0.4 K," he can come up with no evidence whatsoever to back up his claim. Not only that, instead of admitting this he produces more blather and red herrings, causing the host to lose patience, understandably, with the distraction on that thread which he started. And I've said nothing about the simplistic conspiracy thinking expressed with such certainty.

Colour me very, very unconvinced.

May 3, 2012 at 12:45 PM | Unregistered CommenterRichard Drake

RKS, that made me laugh, thanks. One-sided discussion. That's brilliant. Do you do Christmas parties?

May 3, 2012 at 12:48 PM | Unregistered CommenterRichard Drake

RKS, that made me laugh, thanks. One-sided discussion. That's brilliant. Do you do Christmas parties?

May 3, 2012 at 12:48 PM | Richard Drake>>>>

Any more ad-homs while your at it or would you like to give us some REAL science for a change!

May 3, 2012 at 12:50 PM | Unregistered CommenterRKS

I'm open-minded about mdgnn's theory, but he hasn't presented it in a form I can digest yet. Until he does, he can't pour scorn on people 'ignoring' it.

And on your final point, BH is for 'warmists' as well as skeptics. We need more warmists here, either to explain to us why we're wrong, or for us to convert them by osmosis. Or did you prefer it as an echo-chamber?

May 3, 2012 at 1:05 PM | Unregistered CommenterTheBigYinJames

May 3, 2012 at 1:05 PM | TheBigYinJames>>>>

Please don't misquote me, I referred to warmists wearing a sceptic hat.

Argue from an open warmist point of view and we can have a discussion.

I'm sorry if you don't like it but I'm sick and tired of hearing about back radiation on the BH threads day in and day out.

That IS one sided whatever some people may say, and BH doesn't only exist for a small elite clique.

May 3, 2012 at 1:22 PM | Unregistered CommenterRKS

RKS, you've done it again, accusing me of an ad-hom against a determined pseudonym - one of the funniest ideas I've seen. Though I admit that on this you're not original, others seeming oblivious to the fundamental assymetries and applying such pejorative terms as if of equal weight both ways, without thought. No, you're being ad-hom; I'm merely being ad-pseud, at worst.

But it wasn't even being ad-pseud. I genuinely find it laughable for anyone to say that the discussion on BH is one-sided in favour of the standard greenhouse model. There is far too much credence given to and time wasted by alternatives in my book - and that all before mydog's first, breakthrough paper is even seen. Will it ever be seen? What track record does this guy have? To evaluate that we would need a real name. Time-wasting and meta time-wasting is how I would characterise this surreal process.

And of course BigYin is right that your approach craftily sidetracks from the real one-sidedness: not enough of those convinced of the dangers of greenhouse warming posting on Bishop Hill. Those guys laugh at pseudoni like mydog (like Richard Betts not long ago) and stay away. At the very least we need to see a paper, evaluate it and go from there. The current ferment is for me ridiculously one-sided in the credence it gives to this unknown Einsteinian figure about to turn climate physics and perhaps all of 20th century physics on its head. Or not, as the case almost certainly will be.

Let's get back to reality. This is from the recent NYT piece on clouds and the tremendous work over forty years of Professor Richard Lindzen:

Dr. Lindzen accepts the elementary tenets of climate science. He agrees that carbon dioxide is a greenhouse gas, calling people who dispute that point “nutty.” He agrees that the level of it is rising because of human activity and that this should warm the climate.

For every mydog one keeps 'faith with' one loses a Richard Lindzen. It doesn't seem a very effective trade to me. You can call this one-sided if you wish - I prefer nouns like sanity and common sense.

May 3, 2012 at 1:44 PM | Unregistered CommenterRichard Drake

RKS, you've done it again, accusing me of an ad-hom against a determined pseudonym - one of the funniest ideas I've seen. Though I admit that on this you're not original, others seeming oblivious to the fundamental assymetries and applying such pejorative terms as if of equal weight both ways, without thought. No, you're being ad-hom; I'm merely being ad-pseud, at worst......

May 3, 2012 at 1:44 PM | Richard Drake>>>>

What a complete waste of space you've taken up here.

I have always used this acronym throughout my working life and if that doesn't suit your arrogant self that's entirely your problem.

I could call myself Fred Bloggs or any other name but your rude pathetic posts would still be ad-hom.

Get yourself off to a therapist and sort out your weird outlook on life because I'm quite fed up with reading your rude argumentative drivel.

If you keep your objectionable nose out of my posts, I'll do the same for yours, because after the way you tried to imply mydog was a liar for saying he was an engineer you've sunk right to the bottom of the heap in my estimation.

May 3, 2012 at 2:00 PM | Unregistered CommenterRKS

Sorry RKS that you felt unable to deal with any of the substantive points in my post. I also note that you take my principled concerns about pseudonymity as somehow giving you the right to state openly that I am mentally unstable. I would never say the same about you, out of principle - but I again make the point that your accusation is highly defamatory of a real person. You would not pay the same price even if I did repay you in kind. This right to defame those using real names assumed by the pseudonymous on blogs like Bishop Hill has got to be seen as a pathology of the culture.

But that's for another thread. The fact you could not deal with any of my substantive points about mydog and the claimed one-sidedness of the argument here speaks volumes, whoever you are.

May 3, 2012 at 2:31 PM | Unregistered CommenterRichard Drake

Mike Jackson

Mdgnn did seem to dispute the basic theoretical model of the two disc situation. He certainly seemed to be claiming that adding the passive disc between the heated disc and free space would not cause the the heated disc to settle at a higher temperature. As far as I am concerned it is very much conventional physics at this time. Since I have little personal practical experience I choose to believe what I was taught in my A level physics course many years ago. This appears to be still current according to the most recent teaching material I have looked at.

I am not sure that it is possible to give a short precis of the messy reality of the earth system but I am willing to have a go at some of the orthodox theory.

The first thing that is very different is how radiation behaves in gases. If radiation enters a layer of gas some will be absorbed and some will emerge out the other side, virtually none is reflected. The fraction absorbed is a strong function of the exact wavelengths involved and the amounts of the particular molecules making up the gas mixture. Most of the important molecules tend to mainly absorb particular wavelengths within the infrared region and the sun emits most of its power in the shorter wavelengths which are not absorbed within the atmosphere. In principle most of the radiation that arrives at the top of the atmosphere will finish up being absorbed by the surface. If there are no droplets such as are found in clouds and aerosols this can all be quantified with decent precision.

The second important point is that the molecules within the layer will also emit radiation at particular wavelengths according to their particular properties but the emission is very much a function of their temperature. This leads to a "simple" model of the radiation entering and leaving a layer of the atmosphere. You need six arrows to show the quantities entering and leaving. The first one shows the radiation entering from the layer below with the second showing the upward radiation after allowing for the amount absorbed within the layer. The next two are similar but deal with the radiation entering from the layer above and the amount leaving downwards after accounting for the absorbtion. The other two handle the radiation that is generated within the layer. One of these points up to show it is entering the layer above and the other shows the emitted radiation leaving the layer for the one below. These last two amounts are always equal and amount to half the radiation generated in the thin layer.

It is really critical to understand that the absorbtion and emission within the layer are specific to particular wavelengths and compositions. A second important point is that absorbtion is not a strong function of temperature but emission certainly is. It is therefore possible to start at the bottom layer and see what radiation enters it from the surface of the earth and then calculate both the non-absorbed and emitted radiation that will enter the layer above.This can be continued for all the layers above bearing in mind that each will have its own composition and temperature until finally the radiation heads for free space. A similar exercise can be done starting from the top until one reaches the surface where the radiation emerging from the lowest layer is the contentious "back radiation".

Also note that nowhere in these calculations of back radiation or ultimate emissions to space are we attempting to calculate any temperatures. The temperature of the earths surface and the temperatures of the layers are an input to the calculations and not an output. What can be said is that the final amount of outgoing radiation really needs to be the same as the amount absorbed at the surface from the sun if the system as a whole is to maintain an energy balance.

This is actually quite a lot to swallow in one go so I will stop here but will try to answer any questions before getting into things like the lapse rate or the role of convection and evaporation.

Jorge

May 3, 2012 at 2:51 PM | Unregistered CommenterJorge

May 3, 2012 at 2:31 PM | Richard Drake>>>

Sorry but I don't believe you're who you claim to be or that you even have any qualifications above A levels.

Show us your CV as you demanded of mydog or stop pretending you know what you're talking about.

I think you are just hiding behind a pseudonym, because I've never heard reference to your name on blogs covering in depth scientific discussion, and where mydog gets a respectful hearing from contributors who really do know their science.

May 3, 2012 at 2:56 PM | Unregistered CommenterRKS

I'm the Richard Drake who writes this blog and made this submission to the House of Commons Select Committee on Science and Technology in February 2010 - and you, RKS, have defamed me by making disgraceful public statements implying I'm mentally unbalanced. I guess I missed your apology for that so far. And you have again chosen not to deal with with a single part of my critique of mydog and your claim of one-sidedness of the debate here.

May 3, 2012 at 3:12 PM | Unregistered CommenterRichard Drake

Guys ....... calm down.
I did not come here to start a fight.
I asked for a little elucidation which I have got from Jorge. Thankyou, Jorge; I shall go away and read it at my leisure and hope I understand it.
Richard, FFS! Your obsession with mydog and other people's pseudonyms is becoming as tedious as mydogs's with back-radiation.
All I said was that I was inclined (pro tem) to give him the benefit of the doubt. He claims to be an engineer but that is not the sole reason why I trust engineers and technicians rather than scientists.
Engineers and technicians work in the real world where you screw up you get fired — or worse, people die. They also tend to know the extent to which scientific theory works in practice and as far as I can see we are in the middle of a genuine debate about how the Second Law actually works in the real world. (They are also, in my experience, much more likely to admit their mistakes.)
No, I don't know enough science to know whether mydog is right or not. I do know that no-one has come out and said he is wrong. Your Lindzen quote doesn't help. I believe that CO2 is a greenhouse gas and therefore it seems more than likely that increasing it will warm the atmosphere but then you come up against the lack of correlation between CO2 and temperature for much of the 20th century and for the last 10 years so we're not much further forward, are we?
Oh! and hectoring me doesn't work. Let's keep the debate civil.

May 3, 2012 at 3:39 PM | Registered CommenterMike Jackson

May 3, 2012 at 3:12 PM | Richard Drake>>>

I certainly said you have a weird outlook on life and a therapist might help you to deal with that.

I did NOT say you were mentally unbalanced - perhaps you have problems with English comprehension.

You certainly think a lot of yourself. You run a software blog I've never heard about and which did not figure at all in the blog awards this year.

You wrote, along with a multitude of others, a submission to the House of Commons Select Committee. Good for you but so what?

I suggest you get off your high horse and stop talking down to people. You're NOT a climate scientist or a scientist in any other branch of physics as far as I can tell - correct me if I'm wrong.

Your posts to other contributors here have frequently been rude, offensive including attacks of the most personal nature against the messenger rather than the message. With the gall to hide behind some weird idea that because the messenger uses an acronym it's perfectly ok to insult them. Yes, that's weird and that's what you need to get straight. You expect people to offer you an apology but never, ever offer an apology to those you insult on a regular basis.

Your contributions to BH have so far left me completely unimpressed as to their added value to the discussion.

I really don't care WHO you are, only how you come across on the BH threads, and I've already given that opinion.

Now if you don't mind I'd like to get on with discussing the various threads of interest to me, and fending off some of the snide remarks from the disciples of radiative physics.

May 3, 2012 at 3:47 PM | Unregistered CommenterRKS

Can we have a "RKS v Richard Drake: Slapdown" thread somewhere?

No need to be so grumpy everyone. I'd love mdgnn to be right, which is why I'm being extra extra careful with it. I'd love UFOs to be real too, which is why I'm extra skeptical about them too - easy to fool yourself when you want it to be true.

May 3, 2012 at 4:10 PM | Unregistered CommenterTheBigYinJames

RKS, my last post was in response to this:

Sorry but I don't believe you're who you claim to be or that you even have any qualifications above A levels.

Show us your CV as you demanded of mydog or stop pretending you know what you're talking about.

I think you are just hiding behind a pseudonym, because I've never heard reference to your name on blogs covering in depth scientific discussion, and where mydog gets a respectful hearing from contributors who really do know their science.

The links were to show that Richard Drake is indeed my real name - a point which you had just denied - and to establish which Richard Drake I am (and in passing that I have a degree in Maths in Cambridge, not just 5 A-levels, which is greater than zero, and so forth.) I would be very grateful now for an apology for your wrong and insulting statements in the post I've just quoted in full.

Even if you don't have the decency to do that I note again that you haven't dealt with the unpalatable evidence I brought forward about mdog or the idea that the debate here is one sided, includiung the telling quote from the New York Times on Monday about Richard Lindzen where he says that those holding such views as yourself are nutty.

Despite your insults, which remain highly defamatory, with all the bravery that requires from someone hiding behind a pseudonym, I do have a question for you. You said:

I think you are just hiding behind a pseudonym, because I've never heard reference to your name on blogs covering in depth scientific discussion, and where mydog gets a respectful hearing from contributors who really do know their science.

Could you please give URLs of threads - not just the blogs but specific threads - containing 'in depth scientific discussion' where contributors who really do know their science, who I'd like you please to identify by name, give a respectful hearing for mdog. Thank you in advance.

May 3, 2012 at 4:19 PM | Unregistered CommenterRichard Drake