the Air Vent

Because the world needs another opinion

The Concentric Blackbody Problem – Nick Stokes

Posted by Jeff Id on March 2, 2012

I have not had a chance to see Tallbloke’s guest post but Nick Stokes wrote a nice rebuttal to it.   It discusses basic equations for a sphere in a sphere for blackbody calcs.

 

I’ve been arguing over at Tallbloke’s. It’s one of those posts where a sceptic does an elementary analysis and makes elementary errors which contradict “consensus” science. A new scientific discovery is announced. Being Galileos, they don’t have to check their work.

The sceptic here is Hans Jelbring. He looks at a simple problem, two concentric spheres without heat sources, and checks their radiation balance to find what the temperature difference should be. Consensus science says, of course, that there should be none, but he found one, and then spent time working out the resulting perpetual motion machine. I’m not sure what was the point of that, but Trenberth was mentioned.

I have sometimes done these analyses myself, being intrigued when what looks like a problem determined by geometry turns out to have a solution constrained by the Second Law of Thermodynamics (2LoT). Given the complexity, that can look like a miracle.

It’s worth reading because people like to discuss this model and Nick has equations for you.


32 Responses to “The Concentric Blackbody Problem – Nick Stokes”

  1. steveta_uk said

    I’m sure Claes can prove Nick wrong ;(

  2. Mark Cooper said

    I’ve followed some of the debate on this subject over the last few months on WUWT, Tallbloke etc and started digging into the maths, but its too complex/takes too much of my time to get into the nitty gritty of it and so have not commented previously. However, I have wondered why everyone is using something as complex as a sphere for these models- a sphere surrounded by an infinite number of suns could be much more easily modelled using a flat surface with a single infinitely large heat source at an infinite distance. Can anyone who is dead clever explain why no-one has use the simpler model described, instead of trying to model a rotating sphere?

  3. Jeff Condon said

    Mark,

    What you are describing is an infinite plate problem. I prefer it except that the you would need 3 plates to achieve the same discussion.

  4. Gilbert K. Arnold said

    #2; The reason people try to model a rotating sphere is (IMO) because that is the physical situation that we have to deal with. Modeling a sphere brings into play light striking the sphere at varying angles of incidence as well as other complications. Modeling a flat plate is not meaningful related to the Earth.

  5. steveta_uk said

    Does Olber’s paradox rule out an infinite number of suns?

  6. Kenneth Fritsch said

    Nick Stokes makes a couple of good observations here that would appear to me to be more confined to the skeptic side than the consensus on AGW. SteveM has a made an issue of avoiding people using his blog to promote some harebrained concept that would refute how we look at climate change. Refuting the better devised of these harebrained concepts often takes time and space that I would judge could be better spent on other topics.

    As a skeptic myself, I do want to separate “leaving it to the expert scientists” when it comes to refuting basic science that has been well established and accepted by the physics of the matter and what a skeptic can do in analyzing the value and evidence presented in a paper on climate science. I therefore would hope that people discussing these issues would carefully consider and keep separate these two very different aspects of scientific discourse.

    “I’ve been arguing over at Tallbloke’s. It’s one of those posts where a sceptic does an elementary analysis and makes elementary errors which contradict “consensus” science. A new scientific discovery is announced. Being Galileos, they don’t have to check their work…
    ..I have sometimes done these analyses myself, being intrigued when what looks like a problem determined by geometry turns out to have a solution constrained by the Second Law of Thermodynamics (2LoT). Given the complexity, that can look like a miracle.”

  7. steve fitzpatrick said

    The angle of view issues are pretty well known. I am not sure why Nick would waste any time on that argument, but to each his own. Maybe he thinks that you can actually convince someone who has developed one of these nutty calculations/theories that they are mistaken if you just explain it clearly enough. You can’t. It is always a waste of time, because they are quite beyond help. When someone is so naive that they actually report ‘results’ like perpetual motion, violations of the second law, Stefan-Boltzman is incorrect, etc., then anything beyond a simple statement like “You are for sure mistaken because….” is useless. They either see immediately that they are wrong, or they never will. (ragin’) Doug Cotton is the quintessential example.

  8. max said

    1) I doubt HJ is convinced he is right, he just doesn’t know where he made a mistake (when someone claims “if I am right I have discovered perpetual motion”, they know they are wrong)
    2) the error probably didn’t originate with HJ, his numbers are good using his starting point
    3) The error seems to originate in the Gerlich paper (HJ’s ref. 4, figure 3 jumped out at me)
    4) If M. Jelbring is still having difficulty understanding the good M. Stokes explanation of where things went terribly wrong, M. Stokes might be well served by reading the Gerlich paper and referencing it to show where things went of the tracks

  9. Jeff,

    Can’t find your post “If Micheal Mann Knew Science”

    A member of the “Neutron Repulsion” group recommends that all skeptics remember the lesson in “The Man from La Mancha”

    http://en.wikipedia.org/wiki/Man_of_La_Mancha

    Best wishes for a relaxing week-end,
    Oliver

  10. Jeff condon said

    Max,

    Nick has identified the error fairly clearly in his post. While he may have been too harsh in his critique of the effort, that is his personality. I skimmed the tallbloke guest post after I posted this, it seemed fairly innocuous in that the author admits he may have made a calculation error. I didn’t follow the thread to see if it was later acknowledged.

  11. diogenes said

    Jeff…while jelbring said as point one that he might have made an error, all subsequent attempts to show that to him fell on deaf ears….

  12. diogenes said

    but, on the other hand, it’s rather like holding a conversation with Nick

  13. diogenes said

    I have been remiss on checking in but I have noted tha in nthe pastt Nick has condoned:

    rigging peer reviews
    conspiring to destroy careers of other scientists
    faking evidence
    identity theft
    defamation

    etc

    so why not just ask where his ethical boundaries end? Blackmail, murder, arson, kidnapping ……?

  14. Max said March 2, 2012 at 6:19 pm
    1) I doubt HJ is convinced he is right, he just doesn’t know where he made a mistake (when someone claims “if I am right I have discovered perpetual motion”, they know they are wrong)

    You’d think so, but then you’d think he would check and check again. But he goes on at length about how the perpetuum might be constructed. And it’s self-important stuff like this which provoked my testiness:
    “As can easily be understood the consequences for science as such is enormous if my calculations happens to be correct. In that case it is of utmost importance to discuss point 2-5 above very carefully by responsible scientists and apply this new knowledge to a multitude of inaccurate models now in use in the scientific community.”

    As for Gerlich, I think he’s just referring to G&T’s airy statements that he quotes:
    The constant s appearing in the T^4 law is not a universal constant of physics. It strongly depends on the particular geometry of the problem considered.

    They don’t explain or justify that anywhere. I don’t think they do the sphere problem.

  15. Diogenes said March 2, 2012 at 7:42 pm
    I have been remiss on checking in but I have noted tha in nthe pastt Nick has condoned:

    Not true, of course. But relevance?

  16. DocMartyn said

    I thought Reed Coray made the best contribution. Pointing out that is not radiated isotropically was not something I was aware. Applying S-B to curves can be difficult.

  17. Jeff condon said

    “As can easily be understood the consequences for science as such is enormous if my calculations happens to be correct. In that case it is of utmost importance to discuss point 2-5 above very carefully by responsible scientists and apply this new knowledge to a multitude of inaccurate models now in use in the scientific community.””

    Nick, you win this point also. What an amazing statement for a problem that would be thrown at you in the third year of undergrad study. OUCH!! I’m a skeptic again.

  18. Jeff condon said

    Damn! Don’t these idiots realize that the real issues are far more complicated. I will never figure out people, drives me nuts.

    The guy has math skills, works a few equations, comes to a different answer, and concludes that the basics are wrong. ahhhhhh!

    Makes those who question global warming extremism look like a pile of morons.

  19. max said

    Nick,
    I’m just looking for a way to get across to HJ of what his error is, and I am pretty sure he knows he is wrong but just wasn’t getting your explanation. Not that I am any good at explaining things myself (it has been said that my instructions make filling an ice cube tray difficult), but being as poorly skilled at explaining as I am, I have acquired much experience of people not getting explanations and HJs is not an uncommon response. You’re right about G&T2007, it’s just a reflex on my part to blame Gerlich when I see a reference to it near wrong physics.

  20. I long since stopped commented at Tallbloke’s – or even reading Tallbloke’s blog – the main reason being that Tallbloke accused me of dishonestly changing reader’s comments at science of doom. I assumed this was to stop me commenting at Tallbloke’s blog.

    Seeing this article I went and had a look.

    I always suspected that Gerlich and Tscheuschner were
    having a laugh. and seeing this statement from the article helps confirm their sense of humor:

    ..Professor Gerhard Gerlich (ref. 4.) stated two major arguments against the application of S-B law in the atmosphere:

    The constant σ appearing in the T4 law is not a universal constant of physics. It strongly depends on the particular geometry of the problem considered..

    Not that it’s wrong, but the way they have stated it has led many misinformed yet earnest skeptics to restate it as if it is something that climate science doesn’t know, or something revolutionary.

    The Planck law integrated over all wavelengths and all directions arrives at the hemispherical emissive power. That is, the total energy radiated from a planar surface.

    Wow. Who would have thought it? This is in all radiative heat transfer textbooks. (Well, probably all).

    And everyone knows it.

    ..The T4 law will no longer hold if one integrates only over a filtered spectrum, appropriate to real world situations.

    In short, there are reasons to question the validity of the S-B law for physical situations which are not appropriate for its application, such as calculating the power of “Back Radiation” as done by Kevin Trenberth et al (ref. 5)..

    As already commented the S-B law is across all wavelengths.
    “The power of backradiation” – we measure it from pyrgeometers.

    And when it is calculated, it isn’t calculated from the S-B law at all, it is calculated from the integral through the atmosphere and across all wavelengths of all radiating components.

    A skeptic is one who questions things. The defense rests.

  21. Hoping that the moderator can fix my html tags in #20 to
    having a laugh.

  22. SoD,
    I think it is wrong. G&T have just mis-stated the S-B Law. They say (end 2.1.4) the usual right hand side represents:
    “This is the net radiation energy per unit time per unit area placed in the neighborhood of a
    radiating plane surface of a black body.”

    But it isn’t. That would fold in the cos θ terms, and also an inverse square distance term, which is why they say it depends on geometry. But Wiki has it right:
    “that the total energy radiated per unit surface area of a black body per unit time”

    And it is a constant.

  23. DocMartyn said

    I rather liked the thread. I have problems understanding the effects of the difference in the rate of heat transfer in solids, gasses and at surfaces.
    I understand that I am not a physicist and it is probably that the answers to all my questions are in Atkins or similar text books, but I still lack understanding.
    The various sphere problems are very nice thought experiments.

    The one I posed was treated with derision and yet I still do not know the answer as to what the temperatures of the outer surface of my inner radiant sphere, the inner surface of the shell and the outer surface of the shell.

    In a Crookes Radiometer the rotation of the vanes is caused by asymmetric heating of the vanes, due to one side being white and the other black,
    A Crookes Radiometer has been constructed using a uniform, front and back, coating of gold nanoparticles that exhibit a very high photon absorption. Here the vanes have a convex and concave shape asymmetry, allowing one to get work from the light flux.

    http://144.206.159.178/ft/13042/932905/16247978.pdf

    In both cases, these Radiometers have an asymmetric heat profile across the, very thin, blades.

    I wonder if one could construct a sublimating Crookes Radiometer, whereby material from the hot side would undergo more sublimation and the cool side would under go condensation.

  24. stan said

    “Being Galileos, they don’t have to check their work.”

    Nick Stokes on behalf of alarmist scientists who steadfastly refuse to ever check their work or allow anyone else to do so.

    I think this is an example of the pot calling the tea cup black. There may be some skeptics who get smudges on the cup, but to have someone from the “why should I show you my work” side cast aspersions is especially laughable. Nick should cut back on the snark so it doesn’t come back to bite him on the ass so often.

  25. DocMartyn said

    Minefields typically have large signs that state ‘Minefield’. Then have highly visible tapes sowing you the safe path.
    So it should be with science. If there are known pitfalls along the path to understanding, some clear markers would be nice.
    With my own though experiment, Nick gives me a definitive answer, but not understand in terms of efflux and influx rates at the three surfaces.

  26. Kenneth Fritsch said

    I think this is where you separate the true skeptics from those who are skeptical of only the “other” side of the issue.

  27. Nick,

    Good point, I didn’t notice their statement at the end.

    Of course, the S-B law is the total hemispherical emissive power. Not the power experienced in one location.

    But I think we can charitably call their mistake “scientific error” rather than “scientific fraud”..

  28. Michael Hart said

    steve fitzpatrick said:
    “(ragin’) Doug Cotton is the quintessential example.”
    Glad you noticed him too. He’s quite a character, isn’t he?

    I like TallBluerks blog because his was the first one where I read some seriously interesting solar/astronomical alternatives to the usual spiel. I think that’s what they know about, and I think it’s worth serious consideration.

    I have my own reasons for scepticism [like there’s any shortage of reasons] and don’t need N/Z or HJ. Not asserting that they are categorically wrong, but I’m sceptical and my limitations of time and competence mean I will be looking at other things with more interest.

  29. All you have to do is apply the Second Law of Thermodynamics.

    The temperatures must end up the same if you disregard external energy in or out.

    It’s quite simple and doesn’t need any calculations.

  30. Michael

    I like TallBluerks blog

    Yes I do too – you’ll see discussion of solar/astronomical alternatives in my paper there on a dedicated thread … come and join in the discussion about …

    No, Virginia. Microwave ovens do not melt ice. And LW radiation from CO2 doesn’t either.

    http://tallbloke.wordpress.com/2012/03/13/doug-cotton-radiated-energy-and-the-second-law-of-thermodynamics/

  31. ScienceOfDoom

    Just wondering if you can answer why a microwave oven does not melt ice?

    If you study my peer-reviewed paper you may work out that backradiation (like microwaves) doesn’t melt (or warm) ice on the surface either. In fact, with oxygen molecules actually radiating (as NASA knows of course with their sat.temps.) poor old carbon diox. is somewhat outnumbered, slowing only the radiative cooling rate (in a minuscule way) but not evaporative cooling or sensible heat transfer, both of which compensate for less radiation, leaving no net effect.

    A bother isn’t it. Your website may depreciate in value if this news gets out.

    http://climate-change-theory.com

    Jeff

    How are you going with your consideration of microwaves not melting ice?

  32. Doug,

    How many threads do you have to spam with your nonsense?

    First, microwaves do melt ice.

    No, I know you are reacting so I’m putting this here for a delay.

    They melt ice.

    More blah.

    They do it slower because the ice absorption spectrum allows transmission of the waves through the EM field of the electron cloud at a very reduced absorption level.

    This subject is beyond your understanding Doug. You need to start with the simple stuff first. How about admitting you need to delete the bolometer and laser sections from your ‘peer reviewed’ paper.

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