The Monktopus vs the Lucianator
So what’s this about? All that damn math hurts my eyes. Can someone take pity on my meager mental powers and boil this battle down to a nice soundbite?
(As for my headline, partial credit goes to the inscrutable Mosher.)
I’m interested in hearing the significance of this smackdown. Can you make it pithy? Does it have great pith?
Monckton has been publishing such nonsense for years. People have been pointing it out for years. A skeptic with adequate powers of math has finally decided to call him on it.
OK. Monckton fails at high school mathematics.
“the inscrutable Mosher” – inscrutable isn’t the adjective I’d use for someone who mocks (“bug-eyed”) the unpleasant effects of Grave’s Disease. Although as Monckton also crudely mocks others’ appearance, they deserve each other.
As for significance how many people (if any) thought Monckton’s analysis was convincing and changed their mind when Liljegren pointed out the flaws?
Don’t mess with Lucia. That’s all.
I think what Monckton was trying to do was use radiated power = constant * T^4 and the reported values of the radiated power (the forcings F_whatever) and the surface temperature of the Earth to get the implied constant used.
F=s T^4
dF/dT = 4 s T^3 = 4 (s T^4) / T = 4F/T
1/s = T/4F
(1/s being the usual convention for the sensitivity.)
He then took the radiated power 390 W/m^2, multiplied by 4, and divided the temperature by it. He noted that he had only used the radiative forcing, where Kimoto had also included the other forcings as well, and if you wanted to know why you ought to read Kimoto.
I’m not entirely sure (she’s playing Socratic questions), but I think what Lucia is objecting to is that while you can legitimately add them in to the definition of climate sensitivity, because they don’t follow a fourth power of temperature relation, the following algebra doesn’t work. Thus, it’s not simply a matter of adding them to the radiative power in the equation derived at the end.
There’s also some disagreement going on about which “outgoing longwave radiation” is being referred to. Monckton’s calculation refers to radiation emitted by the surface, but the Kimoto discussion appears to refer to that at the boundary of space (which is why the other terms need to be added). Of course, at the boundary of space the effective temperature is different, too.
I think Monckton back-calculated the radiative Stefan-Boltzman constant (OK so far), noticed that Kimoto had added another couple of terms and thought “I’d better add in something about that, just in case” and put the adjusted numbers through the same mill without thinking. It would have been better if he’d just left it alone.
Fundamentally, it comes down to assuming that convection and evaporation are only minor adjustments to the basic radiative mechanism, just because the energy flows are smaller. He’s not the only one ever to have done that.
I got stuck on what is to me a simpler and more obvious point. From his letter to RS:
<i>”The central uncertainty in the debate about climate sensitivity, therefore, resides in the value of the last of the three parameters ““ the overall feedback gain factor G = (1 ““ λ0 f)”“1, where f is the sum of all individual positive and negative feedbacks and g = λ0 f is the closed-loop gain. Process engineers designing electronic circuits customarily constrain g to a maximum value +0.01 to ensure that conditions leading to runaway feedback do not occur. Above 0.01, or at maximum 0.1, there is a danger that defective components, errors in assembly, and the circumstances of use can conspire to cause runaway feedback that damages or even destroys the circuit.”</i>
And so, sure enough, he says g has a “theoretical maximum” value of 0.1, based on this circuit design rule. And this is his constraint on climnate sensitivity.
But it’s noy based on any physics, or any observations. It’s just derived from a supposed (I’ve never heard of it) safety rule of thumb used by engineers designing solid state circuits.
Aguiing that properties of the real atmosphere can be determined from such rules is just bizarre.
“But it’s not based on any physics, or any observations.”
You have a point – this is not an argument I’d take too seriously – but in principle it does have observations behind it. His argument is that over hundreds of millions of years, the climate has stayed within – in absolute terms – very tight bounds. There has never been a runaway. The feedback parameter depends on all sorts of stuff, some of which is variable, and one might expect that if it was at all close to being unstable then natural variation in those factors would likely have pushed it over the edge at some time. So it’s probably a “long way” from instability. A “long way” is a bit vague, but when electrical engineers have faced the same problem practically, they settled on 0.1 as necessary (to reduce costs) and sufficient (to reduce wastage and extend life).
It’s a hand-waving, ball-park, back-of-an-envelope sort of argument, a bit like saying let’s assume the atmosphere is one dimensional and all the day-night, summer-winter, equator-pole stuff is smeared out. He has a point about the climate having been very stable, but without knowing the statistics of all the factors that could vary it (and no reason to think they’re of a similar size to variations in electrical components), it’s impossible to quantify.
<i>”A ‘long way’ is a bit vague, but when electrical engineers have faced the same problem practically, they settled on 0.1″</i>
Well, it isn’t the same problem. Their main issue is with VHF oscillation caused by parasitic capacitances etc. No climate analogue there.
But the number he cites isn’t 0.1, it’s 0.01. He added an “order of magnitude” for no clear reason, but probably because 0.01 would have given a totally implausibly low result. If he’d multiuplied by 20 instead of 10, he’d be back in the IPCC region.
He gives no source for the 0.01, and frankly, I don’t believe him. Engineers design circuits with lots of negative feedback, not a small amount of positive.
<i>”There has never been a runaway.”</i>
There is evidence of <a href=”http://en.wikipedia.org/wiki/Runaway_climate_change#Examples”>sudden jumps</a>.
“He gives no source for the 0.01,”
That would be Dr David Evans.
“There is evidence of sudden jumps”
True. But that’s not a runaway.
“That would be Dr David Evans.”
<a href=”http://sciencespeak.com/DavidEvans.pdf”>Dr David Evans?</a>. Well, he didn’t cite that source (or any other) to RS. Maybe just as well. And the multiplication by 10?
“And the multiplication by 10?”
I think he said “one or two orders of magnitude below unity”.
Yes, but to address KK, there’s no fancy maths here. To resolve “The central uncertainty in the debate about climate sensitivity” he pulls a figure out of the air (maybe via David Evans) which he says is used by engineers for circuit design, “one or two orders of magnitude below unity”, multiplies it by 10 (Why? Lord knows) and cites that as a “theoretical maximum” that the Earth’s climate must obey. So the IPCC is wrong again.
I assume the fancy maths KK was asking about was the bit about differentiating Stefan-Boltzman. This is an entirely separate point, and as you say, cites no fancy maths.
I don’t think it’s correct, either, but I can see where he’s coming from, and it might make another usable approach with a lot more work. Everybody is so intent on trying to insinuate that he is a total idiot that they’re going too far, and claiming mistakes and omissions he hasn’t actually made. That doesn’t mean he’s right, but you’re not going to be able to hold a civilised debate if you feel discrediting him is more important than analysing the arguments, and that isn’t going to persuade anyone not already persuaded. The valid points against his argument get lost amongst all the invalid ones, and casual readers might assume they’re all invalid as a result.
Both sides do it, but it only increases the polarisation of the debate.
He doesn’t multiply it by 10. One or two orders of magnitude below unity is the range 0.1 to 0.01. He takes the upper end of that range as a maximum.
“He doesn’t multiply it by 10. One or two orders of magnitude below unity is the range 0.1 to 0.01. He takes the upper end of that range as a maximum.”
But why would he do that?
@4 “I’m not entirely sure (she’s playing Socratic questions)…”
Heh, that’s a good one coming from you.
Harry, how else would you determine a maximum?
Keith, Yes, I suppose it is. 🙂 I use the method quite a lot.
If people want to know what I’m getting at, I assume they’ll ask.
Keith–
Oh. So now, after the math, I’m going to have to write up the normal human version? Lambert’s bullet is correct. But there is actually a lot more to it (which I suspect Lambert knows). I just woke up and am drinking my coffee. I’ll write more later.
Lambert– I hope you do not consider me sneeringly rude to address you as Lambert. 🙂
On the socratic issue: I did present a quiz as a quiz. That said, I’d discussed he answers in the previous post, which means means I didn’t violate my rule. 🙂
Kieth, you can name-call with the best of them.
Engineers design circuits with lots of negative feedback, not a small amount of positive.
Yes, I think that is the point.
There is ample bloviating on both sides of this kerfluffle.
@15
“If people want to know what I’m getting at, I assume they’ll ask.”
What makes you think that? Speaking for myself, I’ve concluded that you’re more interested in obfuscating than clarifying. And that you are somebody who likes to hear himself talk.
@18
Yes, I realize that cutting Ken Green down to size has prompted you and a few others to make this charge. On that thread, I’ve asked for examples that are equivalent and didn’t get any.
Did you cut Ken Green down to size? How big is he now?
I seem to recall some examples… perhaps I’m disremembering.
Anyway, my comment on this thread was in jest – lighten up, it’s Saturday.
“kieth, you name call with the best of them.”
Oh. Yes, yes, I see it now. Can’t believe I missed the jest there.
Can’t believe I missed the jest there.
Me neither, but I forgive you ;-).
“What makes you think that?”
Probably because it sounds like the sensible thing to do.
“Speaking for myself, I’ve concluded that you’re more interested in obfuscating than clarifying.”
That’s quite a difficult one to answer. I can have a guess at why you would think so, although I doubt you would agree, and I tried asking earlier and got no reply.
I suspect it’s because I talk about things in such a way that the obvious conclusions aren’t the ones you expect, and you are assuming that anything that sounds reasonable but comes to the wrong conclusion must therefore be misleading in some way. And if I’m too intelligent to be doing it accidentally then I must be doing it deliberately. You don’t engage or answer because that would draw you into a position of either having to figure out exactly what was wrong with what I said, which might be very difficult, or having to look unreasonable by disagreeing without being able to say why. It’s easier not to discuss it.
A lot of people find it difficult to understand that other people can genuinely draw different conclusions from what to them seems obvious. My view is that there is very little in this world that is “obvious”, and I like to pull such assumptions apart to see what’s inside. You can learn a lot that way, and it’s a good way of catching mistakes.
But I can see that if you had a nice, simple soundbite picture of the world, and suddenly it’s full of complications, that could seem “obfuscatory”. That’s not meant personally, it’s just the way people are.
I’m sure that’s not how you see it, but that’s why we need to keep asking, if we want to understand. Do you really thing we can reduce the level of destructive ‘taking sides’ in this debate without listening seriously to people who we don’t agree with? Or is the idea just to find some way to get them to listen to you?
However, I can’t think of any way to assure someone that I’m arguing honestly if they’re inclined to disbelieve anything I say as being deceptive.
Keith,
The two errors that Lucia points out are not so much in the math as in the physics.
Some of Monckton’s arguments rely on the relationship between flow of radiated energy and absolute temperature for an ideal perfect radiator, the Stefan Boltzmann equation.
She points out that the Stefan Boltzmann equation cannot be used to determine the relationship between surface temperature and upward movement of energy from the earth’s surface, because evaporation and convection which are part of this flow, do not follow the Stefan Boltzmann equation.
Secondly she points out Monckton’s fall back postion, that the Stefan Boltzmann equation can be used at the top of the atmosphere, together with the reflectivity to obtain the outgoing radiation is dead wrong. The top of the atmosphere is not an ideal black body. Some of the outgoing radiation originates at the surface of the earth and travels through the atmosphere because it is an a radiation band not absorbed by the GHG’s.
Nullius in Verba @ 12
From these errors it is clear that Monckton doesn’t know the basic fundamentals of climatology, and is clearly a pompous idiot. I don’t feel a need to insinuate this, it is clear to anyone who knows anything about the subject, and has any objectivity.
The burden of proof is on you to show how such an ignoramus can produce anything that is valid.
The fact that he gets so much play at Wattsupwiththat shows that Anthony Watts and his audience are also ignoramuses. Taking anything that he writes serious is a waste of time. There is no reasoning with people who accept such tripe.
AGW deniers like Monckton, are fond of claiming that positive feedback mechanisms in climatology will lead to instability and runaway. They are neglecting the fact that the earth’s temperature is ultimately controlled by a negative feedback mechanism, energy loss due to Planck’s law of radiation. This temperature can get very high, as it has on Venus, but spontaneous oscillations are not going to happen, as they do in electronics.
#25,
Thank you Eric. That was an excellent demonstration of what I was talking about.
#26,
Is it really the sceptics who claim all that? You should try asking what they think of “tipping points” some time.
Nullius in Verba,
Once again you are arguing for the sake of arguing.
The fact that Monckton misuses the Stefan Boltzmann equation the way he does, and still claims to be a climate science guru, makes him a pompous idiot.
A tipping point is an inflection point in a response curve, not the same as a negative or zero denominator in a linear feedback equation.
I was wrong, Eric is a much better name-caller.
#29,
Once again, you see only what you want to see, and assume that because you don’t see or understand my point that I don’t have one.
Whether or not Monckton is an idiot, it does you no good to say so. It results in entrenched positions as either side hurl insults, neither side listening, neither side moving an inch. It’s distinctly unimpressive to bystanders, and if you want to make people like Morano and Inhofe happy, then please carry on. As Napoleon might have said, please don’t let me interrupt.
I note that the comment policy here says “No ad homs, no slurs, no personal insults, no name calling, no guilt-by association, no nastiness.” Maybe Keith just hasn’t noticed yet, but I’d like to ask whether that applies to people on the other side of the debate, too? Does it apply to everyone, or just active participants here? It’s easy not to notice name-calling when you agree with the name-caller, but I wouldn’t want to assume such differences where there are none.
My point earlier was about seeking ways to reduce the destructive taking of sides, and you provided a perfect example. I’m not arguing simply for the sake of it.
An inflection point is a point where the curvature changes sign. (Commonly, where the second derivative passes through zero.) I’d be interested to know why that would be a tipping point.
<blockquote>The two errors that Lucia points out are not so much in the math as in the physics.</blockquote>
There are errors in the math <i>and</i> the physics. These are interlaced. I want to try to write something thorough and pithy for Keith. If not pithy, at least in language that doesn’t require someone reading the math to actually be able to <I>do</i> the differential, and also let’s the understand in what sense this is “important” to the kerfuffle. (I figure if I do a decent job, reporters who are trained to identify clear claims and to find an alternate objective source will go ask someone to sort out a technically simple issue about differential calculus.)
There are quite a few things packed in all those posts and counter posts. I also want to make sure readers understand that while I don’t discuss the issue of “gain” Nick brought up (and also of concern to Joel Shore) that issue is also important, as are some other technical issues in Monckton’s letter to RS. My posts attempted to focus on one particular issue which happens to be the <i>first</i> puzzling apparently unsupported (and in fact, unsupportable) claim in Monckton’s letter.
I think you can see that even now, “pith” escapes me. You can anticipate that the post responding to Keith may be long. But I will try to make it approachable for people who don’t know the physics.
“Nullius in Verba Says:
October 1st, 2011 at 8:33 am Harry, how else would you determine a maximum?”
That didn’t answer my question.
The math is trivial (as NiV demonstrated in 5) but the main problem is not in math but in physics. Even Eric sensed that from reading Lucia.
#33,
Sorry. What was your question?
@31 “It’s easy not to notice name-calling when you agree with the name-caller…”
Indeed. I’ve not heard from you till now about name-calling, and presumably you’re referring to Eric’s comments on Monckton on this thread.
Funny that. You’ve never complained before about insults hurled at Hansen, Gore, Obama, etc.
In terms of the comment policy, I admit it can be better and more consistently policed, but that takes much more time and energy than I’m willing to put in. In general, I err on the permissive side, and let both sides vent. But if it steps over the line and readers start calling each other names, I quickly step in. Also, public figures like Monckton, Gore, et al are fair game in my book–as long as the terms being used aren’t grossly offensive.
“Funny that. You’ve never complained before about insults hurled at Hansen, Gore, Obama, etc.”
And I’m not complaining now.
When it came up before, what I said was: “That’s just politicians being politicians. I agree they can cause us some problems, but that’s just the way the world is. We have a whole spectrum on both sides of the debate, from the scientific and educated to the crude and ignorant, and I have absolutely no problem with admitting that we have as much of that on our side as there is on yours. What I argue with is the claims that we only have idiots on our side and you only have the educated on yours.”
That’s the same point I’m making now. I agree that calling Obama and Hansen names doesn’t do our side any favours. (And I’ve been known elsewhere to politely ask people on my side to knock it off if it gets too disruptive.) But I’m saying that calling Monckton and Watts names has the same effect, and puts one on the same level. Either we can play the game where calling public figures names is fair game, in which case we can hardly complain when other people do it or respond to it, or we can try to encourage everyone to raise their game.
I’m not bothered by it. Nothing I can say or do will stop it happening. I’m not planning to police every instance of it. But at the same time its an important social dynamic that is worth commenting on. Particularly with regard to communicating on climate science and resolving the political impasse.
Anyway, thanks for the clarification of policy. That’s helpful, and I’ll bear it in mind next time I want to talk about some climate scientists.
Nullus
Fundamentally, it comes down to assuming that convection and evaporation are only minor adjustments to the basic radiative mechanism, just because the energy flows are smaller. He’s not the only one ever to have done that.
This is not what it comes down to fundamentally. You are conflating the very targeted discussion in my final post with the fundamental issue. The target issue in my final post addresses Monckton’s response in which he refuses to discuss the mathematical and physical assumptions made to develop the equation in Kimoto which Monckton insists is correct. Among other things, Monckton makes some a claim about what application of elementary differential calculus requires, making the claim in a rather high handed way.
Monckton’s claim about what one gets from straightforward application of differential calculus is factually incorrect. His claim that his manipulation is identical to the one in many climatology articles, including Hansen 1994 is factually incorrect. The equation he defends is incorrect.
You are correct that the error in applying the differential may not have a large consequence on the magnitude of the term computed. It is the error in other assumptions– which Monckton does not discuss– that more likely result in larger errors. For example: In Kimito, (which Monckto follows) the derivation includes an unstated assumption that back radiation is not a direct function of surface temperature (under the construct dividing feedback from direct response.)
It is this assumption about back radiation and not the assumptions about convection or evapotranspiration in Kimoto that results in much lower estimates of feedback. That said: All three assumptions appear to have little (or no) basis in physics. In addition, Monckton makes mathematical mistake: that is he incorrectly differentiates a very simple function of the sort one ordinarily learns to solve in the early weeks of taking a course in elementary calculus. Not only that, when that mistake has been pointed out to him, he defends it as correct with quite a bit of vigor. The latter behavior may suggest he doesn’t know how to differentiate. Or it may suggest something else.
Eric Adler Says:
October 1st, 2011 at 11:45 am AGW deniers like Monckton, are fond of claiming that positive feedback mechanisms in climatology will lead to instability and runaway.
This article in New Scientist quoting James Hansen
http://www.newscientist.com/blogs/shortsharpscience/2008/12/nasa-scientist-warns-of-runawa.html
<i>In my opinion, if we burn all the coal, there is a good chance that we will initiate the runaway greenhouse effect. If we also burn the tar sands and tar shale (a.k.a. oil shale), I think it is a dead certainty.</i>
I’m confused
Is Hansen a ‘denier’?
Does the mechanism Hansen uses to arrive at his ‘runaway Global Warming’ scenario not involve positive feedbacks?
Is Hansen simply ignorant of the Physics and the math?
Lucia,
As I said, I agree on it being factually incorrect. What counts as most “fundamental” depends on your point of view, or what you’re trying to say at the time, I suppose.
Since back-radiation has little net effect in a convecting atmosphere, I’d be surprised if it was the most fundamental problem, but I haven’t studied Kimoto so I really couldn’t say. Lots of people get the physics wrong, on both sides of the debate. It’s nothing very unusual.
you want pith. the pith is this. the monktopus is afraid to debate a girl about math.
You know after years of hearing skeptics whine about how nobody will debate them you actually have an offer from lucia to debate something that the Monktopus wrote. The debate is is well defined. The topic is a single paragraph and as Tim Lambert notes requires modest math skills. Instead, the monktopus squirts ink about a dozen other topics and ends up playing a silly game of not using Lucia’s name.
Sashka Says:
October 1st, 2011 at 3:13 pm
“The math is trivial (as NiV demonstrated in 5) but the main problem is not in math but in physics. Even Eric sensed that from reading Lucia.”
There is much wrong with what Monckton is doing. Lucia is just focussing on some of that, not all of it.
Steve (41)
That is something, about not referring to Lucia by her name. Has Anthony Watts, who normally gets worked up into a tizzy over such behavior, said anything about this?
<blockquote>Since back-radiation has little net effect in a convecting atmosphere, I’d be surprised if it was the most fundamental problem</blockquote>Could you clarify this claim and explain why you believe it is true?
Back radiation has an important effect at the surface of the erath, and it is the surface effect that would be included in equation (14) of Kimoto. Kimoto uses the values from K&T 1997 as a springboard to estimate the Planck constant and takes from that figure numerical values to estimate forward radiation, evaporation and convection. In that same figure, back radiation would substantially overwhelm the effect of evaporation and convection and is not negligible compared to forward radiation. Consistency would certainly not permit someone to simply claim that back radiation has a negligeable effect — particularly if they are claiming they computing an Planck parameter that is “implicit” in that figure which shows <I>substantial</i> backradiation.
Nullus–
On this:
Lots of people get the physics wrong, on both sides of the debate. It’s nothing very unusual.
Sure. And in this case, Monckton made lots of errors.
I attempted to engage Monckton by email. My impression is my pressing him to state his assumptions, and explain the mathematical steps set him off . I know for a fact he terminated the conversation– informing me directly.
I blogged to discuss the issues– so as to inform people whoa are interested n the discussion he initated at WUWT.
He responded with bluster, claiming he has made no errors, telling people I had mislead my readers when all I had done was point out he made numerous errors. My impression is he is now, after quite a bit of bluster, admitting one single error but is claiming this sole error has little quantitative impact.
The truth is: the derivation he used contains numerous unstated assumptions, with several having — to put it mildly- tenuous support in the literature. (By tenuous, I mean they appear to be contradicted by our current understanding of physics. By our, I mean engineers as well as physicists and climatologists.) Moreover, correctly accounting for this error would likely affect the numerical value of the “Planck parameter” he thinks K&T “implies” by a factor of 2– putting the value in line with those of others.
Given the sum totality of simple math errors and very tenuous physical assumptions, it can be said that equation (18) in Kimoto, and used by Monckton is as likely to give correct answers as pulling a value out of a hat. The major difficulty is not the terms for evapo-transpiration and convection, but rather, back radiation.
HarryWR @ 39
The thesis of the deniers is that positive feedback would have lead to runaway on earth in the past, and claim there is no evidence for this. Therefore positive feedback is not possible, or highly unlikely. In fact, as a result of analysis of the temperature of the ice ages, and the triggering mechanism, the Milankovich cycles a positive feedback similar to what has been extracted from current climate models has been found.
http://www.columbia.edu/~jeh1/mailings/2011/20110118_MilankovicPaper.pdf
Burning all the oil in the tar sands would result in an atmosphere with 600ppM CO2, which is twice the level found in the past 800,000 years. If the forcing gets to be too large, some new mechanisms may be triggered that would increase the feedback level further and increase the temperature. The models being used are missing some positive feedback mechanisms. One of the best known is the release of methane gas from permafrost in the Arctic region and methane hydrates deep in the ocean. This will happen in stages as the permafrost melts and the ocean warms.
http://www.zero-carbon-or-climate-catastrophe.org/runaway-heating.html
Nullius in Verba,
It is true that lots of people get the basic physics wrong. You are certainly among them in your claim that ” back radiation has little effect in a convective atmosphere”.
I personally don’t pay attention to people who get their basic physics wrong when the pontificate about global warming. Their opinions are clearly worthless.
I don’t know Keith.
I left a comment noting what Monktopus was doing ( same thing as Hansen did to McIntyre ) and have not been back to the thread since. I suppose one could argue that I lost the right to complain about Monktopus’ boorish behavior when I poked a stick in his eye. eh, whatever. Lucia hits him high and clean.
http://www.youtube.com/watch?v=i3Gvfr9GUC0
Me: I prefer the hip check
http://www.youtube.com/watch?v=_Fp_Hg9z2rc
#44,
“Could you clarify this claim and explain why you believe it is true?
Back radiation has an important effect at the surface of the earth”
Certainly. There is a prevailing explanation of the greenhouse effect involving pure radiative balance, that triggers a lot of arguments. Many of the arguments against it are spurious – it is certainly a piece of real physics. However, it only works that way in a non-convective atmosphere.
Climate scientists are aware of this, and also include convection when calculating, however they persist in thinking that these are just minor corrections to the basic mechanism. In the presence of convection their basic mechanism although involving a larger flux has virtually no effect on the result, and the “minor corrections” determine the outcome.
The pure radiative version goes as follows, and I’ll use water rather than air as an example to illustrate the issue with it. We take a deep pond of water with a dark-coloured bottom. Sunlight shines through the water, which is transparent to shortwave, and is absorbed by the surface at the bottom. This radiates longwave IR, but because water is opaque to IR it quickly gets absorbed and then re-emitted in all directions, including back down. Each successive layer of water on top of the previous absorbs and re-emits the radiation upwelling from below.
We can do it quantitatively as follows. We take the topmost slab of water just thick enough to be opaque. It radiates X units of radiation upwards, to match the power from the sun, and being isotropic radiates the same X units down. It’s losing 2X units of power, so it must receive 2X units to balance it (or cool and thus radiate less). The only place it can get this is from the layer below, so the layer below must be radiating 2X upwards, 2X downwards, and be considerably warmer to be able to do so. The layer below that radiates 3X up and down, below that 4X, 5X, and so on to the bottom of the pond.
The radiation each slab emits downwards is called “back radiation”, and this mechanism means that emitted power increases linearly with optical depth, and the temperature in proportion to the fourth root of optical depth.
Since for liquid water each slab of water is around 20 microns thick, it does so very quickly.
This explanation is identical to the one given for air, only with a “greenhouse” medium 20,000 times stronger. If correct, the effect should be very easily observable, and we can study questions like the existence and effect of back-radiation in the lab.
Obviously, it doesn’t happen. This is because any build up of heat near the bottom of the pond is unstable and convects, totally short-circuiting the radiative resistance. The temperature profile in the water is controlled entirely by convection, and it doesn’t matter if you make the water vastly more opaque to IR, it will have no effect on the temperature at the bottom.
Also relevant, it’s possible to suppress convection by varying the density of the fluid, as in a solar pond. In this case, conduction dominates instead, and you get a steep temperature gradient that can reach 90 C within a couple of metres of the surface.
Air works differently to water because it is compressible, and so the adiabatic lapse rate sets a limit on convection. The gradient is controlled by adiabatic expansion/compression, and the intercept is controlled by insolation and by the average altitude of emission to space (which is affected by the concentration of GHGs). Back-radiation, being entirely internal to the atmosphere, could only ever affect the gradient, and in a convective atmosphere meeting the adiabatic limit, it doesn’t.
Back-radiation exists, and is large in magnitude, but cancels out.
#45,
“Sure. And in this case, Monckton made lots of errors.”
Agreed. Lots of people do. And lots of people don’t like admitting it.
But so what? You point out the error, if they don’t understand what you mean then you can explain it in greater detail, and then you move on.
It doesn’t matter whether people accept their errors or not. It doesn’t matter who “wins”, unless you’re playing it as a game, or as political activism. You’ve expressed your view, they’ve expressed theirs, and other people can see for themselves who’s closer to being right.
So, what chcanges if the bottom of the pool is painted white?
Does ALR limit convective transport, or impose a minimum temperature gradient?
Can you build on your swimming pool example to explain how increasing GHG raises the characteristic emission altitude.
#50,
If the bottom of the pool is painted white, then X, the total power that is absorbed and has to be radiated, will be smaller.
#51,
The adiabatic lapse rate will stop convection if the gradient falls below the limit, and sets a maximum temperature gradient by starting convection again when it is exceeded.
#52,
The analogous situation would be pouring more water into the pool. With the pure radiative mechanism, there would be more layers between the top and the bottom, and hence a greater difference in temperature.
The effect with convection allowed is harder to see in the water example, because it is not very compressible and the lapse rate for water is about 0.1 C/km. To all intents and purposes, the adiabatic limit can be ignored and convection carries heat from bottom to top immediately, as fast as required. A bit more water in the pool will make little difference.
Nullius–
Your argument about back-radiation is nonsense. Also, if it were true, ASHREA would be advising engineers designing home heating and air conditioning systems to account for back-radiation when estimating heat loads on buildings. Back-radiation hits the surface.
Lucia,
“Your argument about back-radiation is nonsense.”
Thank you for that detailed and cogent refutation.
Point made, I trust?
Well, I liked the pithy part that came afterwards, which you have ignored.
#56,
OK. Why did you like it?
I thought Lucia gave you a nice concise example of why she thought it was nonsense.
You chose to ignore it.
#58,
I thought it kinder to leave well alone.
What does it mean? Back-radiation from what? Hitting what surface? And why, if what I said was true, would ASHRAE engineers be advised to account for it?
Nullius–
<blockquote>Also, if it were true, ASHREA would be advising engineers designing home heating and air conditioning systems to account for back-radiation when estimating heat loads on buildings. Back-radiation hits the surface.</blockquote>
Well, that’s an interesting “if”. The difficulty is that what you said is untrue. Among other things, this is confused:
<blockquote>Air works differently to water because it is compressible, and so the adiabatic lapse rate sets a limit on convection. The gradient is controlled by adiabatic expansion/compression, and the intercept is controlled by insolation and by the average altitude of emission to space (which is affected by the concentration of GHGs). Back-radiation, being entirely internal to the atmosphere, could only ever affect the gradient, and in a convective atmosphere meeting the adiabatic limit, it doesn’t.
Back-radiation exists, and is large in magnitude, but cancels out.</blockquote>
It’s true that water and air are different. I’m not sure what limit you think the adiabatic lapse rate sets on convection– do you mean upper or lower bound? (It sets one, but not the other. So, you might be saying something true, or you might not.) Back radiation can exist even if it does not affect the temperature gradient with elevation. I have no idea what you think cancels “back radiation”. Even very vigorous convection sufficient to entirely eliminate vertical gradients cannot ‘cancel out’ down welling back radiation — at least not in the sense of blocking it from hitting the ground.
The convection which must occur to overcome hydrodynamic instability (and moves temperature variation toward the adiabatic lapse rate) does not magically block photons from zinging around, and does not eliminate back radiation. Convection due to wind doesn’t block a back radiation. Convection in furnaces doesn’t block back radiation from fly ash.
As for ASHRAE:
The fact that ASHRAE advises engineers to account for back radiation is evidence that engineers must accept its existence if they wish to correctly estimate the heat flux on walls, roof, and windows on buildings. The advise is not provided to cozy up to ‘kookie’ climatologists who want to convince the public of the existence of back radiation. Engineers who deny back radiation and then try to design home heating or cooling systems discover their systems fail. Engineers who accept it can properly size their systems.
Even if ASHRAE had no explanation for the cause of back radiation and had only empirical (i.e. observational) evidence of it’s existence, the fact that your theory fails to explain observational evidence is a sign that your theory is wrong. The fact is: engineer’s explanation for back radiation is exactly the same as climatologists explanation for back radiation.
Nullius–
On these:
Back-radiation from what?
The atmosphere including clouds, water vapor, any particulates etc. That is: exactly the same things climatologists think back radiates.
Hitting what surface?
Whatever surface the engineer needs to consider: Roof, wall, windows etc.
If you wish to know more and want to compute magnitude of back radiation the way engineers designing buildings do, you can find suitable functions to compute the diffuse radiation hitting a surface here:
http://rredc.nrel.gov/solar/pubs/bluebook/appendix.html
It happens to be on solar collectors– because someone brought up solar collectors at my blog. Look for the paragraph beginning:
The sky radiation ()
This exact same formula would be suitable for computing the diffuse radiation on a surface like a roof, wall or window, but in this case, you use the angle of inclination or the surface (i.e. roof, wall or window) to the horizontal. The climatology problem is easier than the engineering one for that case, we are concerned with diffuse radiation hitting the ground, which is horizontal so the tilt is 0 making cosine(beta)=1 and sin(beta)=0.
You can find data for diffuse and solar radiation at various cities here: http://rredc.nrel.gov/solar/pubs/NSRDB/
How does one calculate the differential of characteristic emissions altitute w.r.t. CO2?
(genuine question, BTW)
Lucia,
Thank you! A lot more detail! But now I’m confused.
You said earlier that if what I said was true, ASHRAE engineers would need to calculate back-radiation, as if that were proof that it wasn’t true because they didn’t. Now you’re saying that they do account for back-radiation. Which is it? Did you mean to say that if what I said was true they wouldn’t need to account for it?
You said that what I said was untrue. So I expected what followed to be the untrue thing I said, but then you say only that it might or might not be true. You agree that air and water are different. You agree that the adiabatic lapse rate sets a limit on convection. So which bit of that was untrue? Did you mean only the last bit?
You say “Back radiation can exist even if it does not affect the temperature gradient with elevation. I have no idea what you think cancels “back radiation”. Even very vigorous convection sufficient to entirely eliminate vertical gradients cannot “˜cancel out’ down welling back radiation “” at least not in the sense of blocking it from hitting the ground.”
But I have said several times that back-radiation does exist, and I have not suggested anywhere that the cancellation results in it not hitting the ground. It does hit the ground. It does get absorbed and result in heating. I meant cancellation in the sense of cancelling its net effect on surface temperature, in the context of the greenhouse effect in a convective atmosphere.
I have a feeling that you didn’t actually read what I wrote, that you only skimmed it and vaguely noted something about back-radiation being cancelled, and you assumed that I was one of those who deny that back-radiation exists. Your argument is directed against a position I’m not taking. Is this the case, and do you perhaps want to have another go?
Nullius
You said earlier that if what I said was true, ASHRAE engineers would need to calculate back-radiation, as if that were proof that it wasn’t true because they didn’t. Now you’re saying that they do account for back-radiation. Which is it? Did you mean to say that if what I said was true they wouldn’t need to account for it?
I mean:
1) Engineers do account for the heat from back-radiation. ASHREA advises this, and has since long before I was an undergraduate and took building design as an elective..
2) My interpretation of what you wrote is that you think if your description of back radiation held true, engineers would not account for back radiation. But they do account for back radiation.
I meant cancellation in the sense of cancelling its net effect on surface temperature, in the context of the greenhouse effect in a convective atmosphere.
Back radiation has a net effect on heat load for buildings. All other things being equal (i.e. design of walls, insulation, windows etc.) back radiation has a net effect temperature of a building surfaces, interior etc.
As far as I can tell, you are suggesting that if back radiation does not affect the lapse rate, then it does not affect the temperature of the surface. This connection is incorrect.
As for what you said that is false:
Back-radiation, being entirely internal to the atmosphere, could only ever affect the gradient, and in a convective atmosphere meeting the adiabatic limit, it doesn’t.
Back-radiation does affect the surface temperature. The idea that it can only affect the gradient is false.
Back-radiation exists, and is large in magnitude, but cancels out.
This is neither true nor false, but simply vague. You haven’t said in what sense it cancels out. With respect to affecting the surface temperature, or heat loads on building, it does not “cancel out”.
kdk33
How does one calculate the differential of characteristic emissions altitute w.r.t. CO2?
(genuine question, BTW)
I don’t know now to calculate the differential of the emissions altitude. Why do you ask?
Nullius–
I do see the confusion. In 54, I left out a ‘not’. ASHREA absolutely does advise engineers to include back radiation. Back-radiation does hit the surface.
I don’t have the physics chops to fully understand the discussion. But it appears to me Nullius and Lucia are talking past each other.
Nullius seems to be talking about outdoors where convection happens unimpeded, and Lucia seems to be talking about interior where convection is suppressed. To me they don’t appear to be similar situations.
#62,
As I understand it, one uses an iterative procedure where you start with a temperature profile, use an model of atmospheric emission/absrption such as MODTRAN to determine the radiative balance through it, determine how that will affect temperature, clip any parts that exceed the adiabatic lapse rate, and then repeat. Eventually you converge on a consistent solution that matches temperature profile and radiation to/from each part of the atmosphere. Manabe and Strickler 1964 is a good place to start. Section 2.
http://www.gfdl.noaa.gov/bibliography/related_files/sm6401.pdf
Also of interest might be Soden and Held 2000, the section starting on p447 entitled “energy balance”. The start of that section will probably look a little familiar, if you’ve read my post above. (Heh.) The later parts discuss the incorporation of water vapour feedback into the CO2 sensitivity calculation.
http://mathsci.ucd.ie/met/msc/ClimSyn/heldsode00.pdf
#65,
Lucia,
I’m not sure what to advise, other than to suggest going through the water pool example, verify that it satisfies the conditions for the usual back-radiation-based explanation of the greenhouse effect, and then consider why all the back-radiation – which I agree absolutely does exist – does not result in a massive greenhouse warming effect at the bottom of every puddle of water.
Perhaps my mistake was trying to cover everything at once.
SM says
“you want pith. the pith is this. the monktopus is afraid to debate a girl about math.”
Mockton likes to call Al Gore “Al Baby”. Like to see him try the same thing with Lucia 😉
Bob Koss–
Lucia seems to be talking about interior where convection is suppressed
I am talking about outdoors. I understood Nullius to be talking about outdoors. For example, I mentioned “i.e. roof, wall or window)” I mean the outer side or windows, the outer side of walls and, of course, roofs are outdoors. Ceilings are indoors.
Both direct and back-radiation hit the exterior of buildings.
Even when convection is rip-roaring fast, it does not prevent back radiation from hitting an exterior surface like a roof, exterior pane of a window, an exterior wall, or the surface of the earth. The back radiation must be included in the calculation of the the heat load to estimate the temperature.
How much difference back radiation will make to the temperature in a particular application will depend on other factors (how hot the interior of the building is being held by heating equipment etc. But back radiation doesn’t just “cancel out”. )
Lucia,
Agreed.
Bob,
I think Lucia was just confusing me with some other people. I’m sure we’ll get it sorted out.
kdk33,
Sorry, my reply to your query about emission altitude had links, so it’s been held up. Should be there soon.
@ Nullius (49)
Also relevant, it’s possible to suppress convection by varying the density of the fluid, as in a solar pond. In this case, conduction dominates instead, and you get a steep temperature gradient that can reach 90 C within a couple of metres of the surface.
From the rest of your presentation I am assuming that you actually do know the units for gradient. So I won’t be nitpicking but simply ask for a reference.
NiV, It’s not there yet, but thanks!
Lucia, The reason I’m asking is because: if as NiV is suggesting, the real atmosphere exists near the limit imposed by the ALR, then the amount of surface warming we should expect with increasing CO2 is (I’m thinking, but could be wrong, so please correct)…
(delta_CO2)*ALR*d(CEA)/d(CO2)
ALR == adiabatic lapse rate (say deg C/1000ft)
CEA == characteristicv emissions altitude (say 1000ft)
CO2 == CO2 (say ppm)
(assuming linearity)
(Units are a preference)
(absent feedbacks)
Sashka,
You need to highlight a different bit.
In this case, conduction dominates instead, and you get a steep temperature gradient that can reach 90 C within a couple of metres of the surface.
Is that clearer?
I’d suggest Googling the term “solar pond energy generation”, as I’m not having much luck with links. Wikipedia gives one example, but I’ve no doubt you’ll want to find something better.
65– I’m not sure what to advise, other than to suggest going through the water pool example, verify that it satisfies the conditions for the usual back-radiation-based explanation of the greenhouse effect, and then consider why all the back-radiation ““ which I agree absolutely does exist ““ does not result in a massive greenhouse warming effect at the bottom of every puddle of water.
Perhaps my mistake was trying to cover everything at once.
I haven’t been asking you for advice. I am simply telling you your discussion of back-radiation in the atmosphere is nonsense. I have no idea why you think there is any mystery about why there is no massive greenhouse warming effect at the bottom of a puddle of water.
#76,
I haven’t been asking you for advice. I am simply telling you your discussion of back-radiation in the atmosphere is nonsense.
Yes, I know. Did I remember to thank you for making it so easy? Thank you!
I have no idea why you think there is any mystery about why there is no massive greenhouse warming effect at the bottom of a puddle of water.
Excellent! So it would be dead easy for you to say why.
oops, linearity shouldn’t apply, the relationship is logarithmic so
delta-ln(CO2)*ALR*d(CEA)/d(lnCO2)
But, per NiV, I guess there’s no analytic solution, just a numerical approximation. Fun with Mathematica, maybe.
ahhhh, NiV, your links have appeared.
I’ve glanced, but not read them yet (busy with Ikea furniture), but Figure 1, page 447 seems to capture the concept I think I’ve gleaned from your description.
I usually come to CaS for amusment. Today I’ve learned something.
Thank you! I appreciate that.
Nullius in Verba @49,
Your example of a swimming pool is a case of misdirection. You can’t use water, which has much different properties for heat conduction, radiation and convection from air to make an argument about back radiation from air.
You say,
“We can do it quantitatively as follows. We take the topmost slab of water just thick enough to be opaque. It radiates X units of radiation upwards, to match the power from the sun, and being isotropic radiates the same X units down. It’s losing 2X units of power, so it must receive 2X units to balance it (or cool and thus radiate less). The only place it can get this is from the layer below, so the layer below must be radiating 2X upwards, 2X downwards, and be considerably warmer to be able to do so. The layer below that radiates 3X up and down, below that 4X, 5X, and so on to the bottom of the pond.”
You calculation is nonsense. The amount of radiation emitted by the top layer has nothing to do with the amount coming downward from the sun. It is purely a function of the temperature of the surface skin layer. There is no law that says the radiation from each layer increases arithmetically as the depth below the surface increases. It is solely dependent on the temperature profile. The temperature gradient would be huge if your assumptions were correct. The pond would explode as it gets deeper. Think of how many 10 micron layers there are in a swimming pool 1 meter deep -100,000. According to the Stefan Boltzmann equation, the absolute temperature of the bottom layer will be 17 times the absolute temperature of the top. Assuming the top is 280K the bottom layer would be 5000K. Clearly this doesn’t happen.
It is pretty clear that you don’t understand the physics, and despite your pretensions of being a great intellect. This is the clearest example of the Dunning Kruger effect that I have seen on the internet so far.
Nullius–
I said I don’t know why you think there is any mystery. I know you seem to think there is a mystery– but I don’t know what you think it is, nor why you think it’s a mysteries.
But one of the reasons I don’t know why you think there is some “mystery” I don’t even know precisely what you think doesn’t happen. Do you think the bottom of solar ponds are never warm? Do you think something doesn’t happen at the bottom of a 1″ deep puddle of water? (What?) Do you think there is zero heat flux arriving at the bottom of a solar pond due to back radiation? In short: I know there is some issue you want me to think of, but I don’t know what it is.
So, if you think the solar pond question reveals something, why don’t you:
1) Set up the geometry you are worried about (1/8″ puddle? 6ft deep solar pond? Ocean? Salty? Fresh? Dark bottom? Light bottom? No bottom?)
2) Describe the transport equations you think apply.
4) Describe the boundary conditions at the top and bottom.
5) Describe what it is you think happens and why,
6) Explain what the heck you think it has to do with evaluating back radiation at the surface in moist air & /co2, which has a much different density, kinematic viscosity, etc .
Because I have no idea what you are driving at, and I’m not going to try to guess what the question is in the hope of having whatever “aha!” moment you think it would give me if I manged to guess what question you think is revelatory and then found the answer.
If you have done some mystery problem with some mystery geometry etc and can show it disproves back radiation in the atmosphere, go ahead and show it.
Nullius
We can do it quantitatively as follows. We take the topmost slab of water just thick enough to be opaque. It radiates X units of radiation upwards, to match the power from the sun, and being isotropic radiates the same X units down.
Oh. When you set up your problem: Do correct this step in your hand waving discussion. Remember the topmost slab of water is in contact air. The water at the surface can evaporate and heat can transfer to air by convection (and in unusual cases conduction). Presumably some energy comes in by conduction, convection or radiation from below. There is absolutely no reason for the amount of energy radiated from this slab to match the power from the sun. Remember to do a real energy balance on the layers.
So: In other words, I suggest you go through your own mystery problem, note the important differences between it and problem in the atmosphere. Satisfy yourself that these difference really matter, and then ask yourself why anyone should think your pool problem presents any sort of refutation of back radiation affecting the temperature at the surface of the earth.
Nullius in Verba,
@68
Consider a vacuum. The only mechanism of heat transmission possible is radiation. Add a few molecules of gas at low density. This creates the possibility for a tiny amount of energy transmission via conduction and convection, but the predominant mechanism is still radiation. There are too few molecules to carry much energy through space to do much in the way of transmission. This is why radiation is the main method of transmission of energy through air, and why convection and conduction are more dominant in liquids and solids.
So the main energy transmission method in a pool of water is indeed convection. This has no bearing on what happens in a gas like air.
You have delusions of grandeur if you think that you are smarter than scientists who have devoted their lives to the study of climate.
Eric–
There is plenty of heat transfer by convection in air.
In air, if you try to estimate temperature profiles based on radiation only, the temperature decreases very quickly with elevation. But cold air is denser than warm air.
So, static air (as if that every happens) with heavy cold air above the lower density warm air. Now, imagine you create a “ripple” so some lower density air is a bit above, and some higher density air below a plane. The ripple with grow– mixing will happen etc. The mixing will result in heat transfer. Anyway, it turns out there as a particular temperature gradient that is stable–using a combination of thermo and hydrodynamics, you can find this.
Anyway, the temperature gradient will follow the lapse rate– and there will be lost of convection. But this doesn’t mean the surface temperature will be unaffected by the back-radiation. The surface temperature is affected by back radiation.
Nullius,
I’ve read Wikipedia article that claims that the temperature of the bottom layer could reach 90C but of course not the temperature gradient. The article doesn’t say how large it is.
Eric (83)
This is why radiation is the main method of transmission of energy through air, and why convection and conduction are more dominant in liquids and solids.
Why don’t you read something like Introduction to Physics of Atmosphere?
I’ve read Wikipedia article that claims that the temperature of the bottom layer could reach 90C
The gradient is going to depend somewhat on geometry and how the engineers are inhibiting convection. If you add no salt, the onset of Rayleigh-Bernard convection limits the temperature difference from top to bottom of a shallow solar pond. See: http://en.wikipedia.org/wiki/Rayleigh%E2%80%93B%C3%A9nard_convection
I don’t know the limit with salt whose purpose is to permit larger gradients.
As you can imagine, if it gets too hot locally the local hydrostatic pressure would fall below the the vapor pressure for water, and it would boil. This is a design constraint any engineer is going would bear in mind. Boiling would sure as as shooting result in convection! The heat loss would be a killer resulting in a very bad solar pond.
Bear in mind also: the whole reason someone makes a solar pond is to draw off heat. So, unlike the atmosphere, heat is being drawn off from the bottom and used in some engineering process. It’s unlikely anyone would design a solar pond to just sit there, get really hot at the bottom and boil!
The heat drawn from the bottom of the solar pond is another thing Nullius has to account for when he gets around to fully analyzing solar ponds and the atmosphere, noting the differences between a solar collector and the atmosphere. There are quite a few differences!
#79,
Thank you. Yes, S&H was where I first saw the explanation. I’ve added refinements since, but it always amuses me to see believers desperately trying to disprove their own peer-reviewed climate science.
#80,
Hurrah! Well done, Eric! You’ve got it!
“The amount of radiation emitted by the top layer has nothing to do with the amount coming downward from the sun.”
That’s required by heat balance at equilibrium. Just as the energy radiated from the top of Earth’s atmosphere is the same as that received from the sun at the bottom. The skin layer (i.e. topmost slab) adjusts its temperature to make this so.
“There is no law that says the radiation from each layer increases arithmetically as the depth below the surface increases. It is solely dependent on the temperature profile.”
Apart from the first law of thermodynamics, you mean?
“The temperature gradient would be huge if your assumptions were correct. The pond would explode as it gets deeper.”
Excellent! You got it! That’s exactly the point.
The exact same greenhouse effect explanation you so blithely apply to the atmosphere, would cause the oceans to explode if it was true.
I know perfectly well why those assumptions are incorrect – and that the same error occurs when you apply it to the atmosphere as well. I’ve already told you what it is. But we’re making fine progress.
#81,
Lucia, the solar pond example is part of the follow on, confirmation. Sorry, that was confusing. What I was trying to lead you towards was the argument with the plain non-solar pond that Eric has just gone through.
#82,
“Remember the topmost slab of water is in contact air.”
I’m not sure whether it would be less confusing to say “suppose it’s in contact with vacuum instead” as a way of improving the analogy with the atmosphere, or to say “ignore it, it’s not important to the physics”. Whatever you like. It doesn’t matter.
“Presumably some energy comes in by conduction, convection or radiation from below.”
Radiation, yes.
“There is absolutely no reason for the amount of energy radiated from this slab to match the power from the sun.”
All the energy that enters the pond has to leave it, or the pond as a whole will warm up or cool down until it does.
“In other words, I suggest you go through your own mystery problem”
I have done. I already know why it goes wrong – it’s exactly the same thing that goes wrong with the standard back-radiation argument. That’s what I’m trying to explain.
#83,
Consider a greenhouse gas, like water vapour, floating around in a large volume with sunlight shining through it. Has a greenhouse effect, right? Now pump more in to the same volume, squeezing what was there, so it’s denser. Still a greenhouse. Squeeze it even more. The greenhouse gets stronger. Squeeze it until its density is 20,000 times what it is in the atmosphere. It never stops being a greenhouse, only now it’s doing it at super-intensity! A super-greenhouse, giving a massive temperature rise, yes?
#84,
Yes, good. That’s the next bit.
#85,
The top of the solar pond is at the ambient temperature where the pond is.
Lucia @84,
I didn’t claim that convection is not important or nonexistent as a means of heat transfer in the air. Radiation dominates convection of average in the atmosphere. The air in not dense enough for conduction and convection to dominate. That is what the climate science says.
Nullius,
@63
You said,
“But I have said several times that back-radiation does exist, and I have not suggested anywhere that the cancellation results in it not hitting the ground. It does hit the ground. It does get absorbed and result in heating. I meant cancellation in the sense of cancelling its net effect on surface temperature, in the context of the greenhouse effect in a convective atmosphere.”
This is sophisitic doubletalk, which is your stock in trade. If the temperature of the earth is stationary on average, then all of the effects which cool or heat the earth’s surface cancel. That doesn’t make back radiation insignificant. Take away GHG’s and one gets an average steady state temperature that is 33C colder because back radiation goes away. Add more GHG’s and the temperature will go up.
Nullius–
Eric has said you are wrong– and he is correct.
Eric
The air in not dense enough for conduction and convection to dominate. That is what the climate science says.
This is true at the top of the atmosphere. Radiation dominating at the top of the atmosphere is what climate science says– and correctly. If that’s what you meant you are correct. But I wasn’t sure if that’s what you meant.
So, I wanted to clarify the issue lower down. Convection does matter a lot at the surface. This is accounted for in simple 1-d radiative convective problems– discussed in lots of undergraduate text books. Convection is one reasons you are correct when you write
“There is no law that says the radiation from each layer increases arithmetically as the depth below the surface increases. It is solely dependent on the temperature profile.”
In a more-or less standard 1-d radiative convective model of the atmosphere, radiation does not need to increase arithmetically as depth, and it need not in a solar pond. Nullius seems to be describing a pure radiative model– which no one believes applies to the atmosphere. Then, he’s saying that’s wrong because it doesn’t describe what happens in a solar pond. Well… no. It doesn’t describe what’s in a solar pond, and it doesn’t describe what’s in the atmosphere.
And then he’s making a whole lot of other mistakes about the solar pond. And he seems to be making a whole bunch of other weird conclusions.
I’m thinking if you guys (esp. Eric) spent less energy name-calling and more energy thinkin’ you could sort this out PDQ.
NiV says the temperature gradient is determed by convection, which must be true if it lies near the ALR. He says GHG will change the effective emissions altitude, which is tantamount to saying it will change the surface temperature (by changing the intercept). Lucia and NiV seem to be in agreement here.
NiV used the solar pond and swumming pool to illustrate the importance of convection – that’s all.
So, you seem to be arguing about how “important” back radiation is. A salient question might be: important to what? Slope or intercept?
Eric
“The amount of radiation emitted by the top layer has nothing to do with the amount coming downward from the sun.”
Nullius:
That’s required by heat balance at equilibrium. Just as the energy radiated from the top of Earth’s atmosphere is the same as that received from the sun at the bottom. The skin layer (i.e. topmost slab) adjusts its temperature to make this so.
Nullius, could you please define what you mean by “radiation”? As opposed to convection, evapo-transpiration or conduction? Forcing your self to remember what radiation is might help you avoid utter misapplication of the 1st law of thermo.
Forr a solar pond Eric is certainly more correct than you are.The amount of radiation emitted from the top layer does not need to balance the amount coming downward from the sun and in a solar pond, the amount emitted from the top layer has very little to do with the amount coming downward from the sun. The “heat balance” on a solar pond does not require the radiation to balance at the surface of a solar pond. If you write down the heat balance correctly, you will see that it absolutely does not require radiation ingoing to balance radiation outgoing at the surface of a solar pond.
In contrast, the heat balance at the top of the atmosphere does require the amount of energy emitted to balance the incoming energy.
To understand this you need to understand how to actually apply a “heat balance” and also recognize why the assumptions about conduction and convection at top of the atmosphere vs. top of a solar pond differ and why these matter.
Eric-
“There is no law that says the radiation from each layer increases arithmetically as the depth below the surface increases. It is solely dependent on the temperature profile.”
Nullius
Apart from the first law of thermodynamics, you mean?
Eric is correct, in the general case for a solar pond with convection, conduction and radiation, the first law does not require radiation at each layer to increase arithmetically as depth below the surface increases. I suggest you write down the full heat balance including absorption and re-emission, convection and conduction and you will see this is so. the constitutive laws for each stating what you mean by ‘radiation’ etc..
Nullius
The exact same greenhouse effect explanation you so blithely apply to the atmosphere, would cause the oceans to explode if it was true.
Among the problems with your argument is are not applying the “same greenhouse effect” explanation to the pond and the atmosphere. What you are claiming applies in the pond isn’t even claimed to apply in the atmosphere (for example: radiation does not need to increase linearly at each layer). Go find a simple climate text book. It’s true that they will start by explaining a simple pure radiative model– but then explain how there is something missing. Then go read “radiative convective model”!
Also, even if someone somewhere in climatology believed that the pure radiative model applies in the atmosphere you (not they) are misapplying conservation of energy at the top of the pond. You are mis-applying conservation in the interior of the pond. The differences in these do affect what happens in a solar pond!
Nullius
I’m not sure whether it would be less confusing to say “suppose it’s in contact with vacuum instead” as a way of improving the analogy with the atmosphere, or to say “ignore it, it’s not important to the physics”. Whatever you like. It doesn’t matter.
Uhhmm…. and then it would all boil away and not be a solar pond?
The fact that the top boundary condition is not a vacuum makes a huge difference to what happens in a real, honest too goodness solar pond relative to the atmosphere. You can’t just say “X happens in a real solar pond. But now, in analyzing a solar pond, let’s apply ‘assume’ totally unrealistic conditions at the top and do some math!”
You imposing an incorrect assumption about what happens at the top of the real pond would affect the solution for what happens in a real solar pond.
Nullius
All the energy that enters the pond has to leave it, or the pond as a whole will warm up or cool down until it does.
Honestly, I don’t know where you get your really weird ideas about solar ponds
First: No. Solar ponds are sometime operated in transient mode. These do warm up and cool down and you need to account for that when applying the first law of thermo.
Second: In steady state operation, all heat entering the pond does hav to leave. But this does not mean it has to leave through the top. In fact, any solar heat lost from the top is considered an inefficient waste of energy from the point of view of the operator and designer. Heat is removed from the bottom of solar ponds by the people who went to the trouble and expense to build them precisely because they want to remove heat from the solar ponds.
it’s exactly the same thing that goes wrong with the standard back-radiation argument.
Before you conclude this, maybe you should consider the fact that
a) You’ve misapplied the boundary conditions at the top and bottom of the pond. (And by suggesting we should just assume the top of the pond is a vacuum, you give the impression that you think making unphysical assumptions about the conditions at the top of the pond could still result in a decent explanation of what happens in the pond!)
b) You’ve mis-applied the 1st law of thermo at the top, bottom and interior of the pond.
c) You aren’t even comparing your botched pseudo-analysis of a solar pond to the prevailing simple 1-d radiative convective model (i.e. standard back-radiation argument) for the atmosphere!
@ 87
The top of the solar pond is at the ambient temperature where the pond is.
Clearly. But lacking the information about the depth of the pool there is nothing to be inferred about the temperature gradient.
@ Lucia
I think Nullius is trying to teach us a lesson about back radiation by setting up the solar pond example. If we understand why there is not a temperature explosion towards the bottom we’ll see what we misunderstand about the atmosphere.
Lucia,
You’re getting lost in the weeds. Zoom out about 20,000 feet.
@95,
You’ve got it backwards. Lucia is cutting through the weeds that Nullius has put up (his stock in trade, as Eric noted). Of course, I wouldn’t expect you to see that.
But those who are viewing this exchange objectively can see it for what it is.
kk: Can someone take pity on my meager mental powers and boil this battle down to a nice soundbite?
On that level, it’s a “skeptic” (“luke-warmer” or what not) trying to appear reasonable by challenging the most obviously extreme of the “skeptic” crowd, which is usually confined to a few people, such as Monckton or Morano.
@96,
Nonsense, but i wouldn’t expect you to know better.
I know nothing of NiVs stock in trade and can only speak to this kefluffle within a kerfluffle.
The solar pond versus swimming pool example is simply to illustrate the role of convection – that’s all. Lucia’s criticisms are valid given the construct in her mind, but that is not the context in which it was offerred.
They are stuck on the “importance” or “not importance” of back radiation.
NiV says convection sets the temperature gradient, not radiation, and he’s right if it lies close to the ALR.
Lucia says back radiation is important because it changes the surface temperature. She’s right. NiV agress she is right when he says GHG change the characteristic emission altitude (same slope X higher altitude = increased surface temperature).
NiV writes with a tone that puts Lucia off (or maybe they have a history, I don’t know) and is here being conceptual. Lucia is mired in the details and is missing the (rather simple) point, and is beligerent.
The bottom line is that they agree on the key point: do GHG change surface temperature.
They are talking past each other because NiV said back radiation “wasn’t important”, which seems to have Lucia in a tissy.
As I said, the salient question is: important to what? it is not important in setting the temperature gradient, but it is important in setting the CEA, hence the surface temp.
Anyone viewing this exchange objectively would see that they both have something to offer each other. But it’s more fun to have a pissing cotest, I suppoes.
Anyway, not my fight.
@97
I don’t share the sentiment (“trying to appear”) indicated by your back-handed compliment to Lucia.
If only more people putatively aligned with the opposing camps were similarly “reasonable” and took on the extremes.
Sashka–
think Nullius is trying to teach us a lesson about back radiation by setting up the solar pond example. If we understand why there is not a temperature explosion towards the bottom we’ll see what we misunderstand about the atmosphere.
I think he is trying to teach us that. But all he is doing is misapplying physics for a solar pond, misapplying physics for climate and claiming that we would learn something by examining what would happen if his wrong physics were true.
I could ponder what would happen to the economy if people captured a millions leprechauns and took their gold. But this would tell me nothing about the economy. Similarly, Nullius’s solar pond example tells us nothing because he’s applying Leprechaun physics.
NiV writes with a tone that puts Lucia off
I don’t haven’t noticed anything bad about NiV’s tone. I’m saying his physics and claim about back radiation’s effect on surface temperature is wrong.
Saska
The bottom line is that they agree on the key point: do GHG change surface temperature.
They are talking past each other because NiV said back radiation “wasn’t important”, which seems to have Lucia in a tissy.
Do we agree that backradiation increases the surface temperature above what it would be without back radiation? What Nullius writes at least appears to say that back radiation doesn’t affect surface temperature:
For example, he wrote this:
I meant cancellation in the sense of cancelling its net effect on surface temperature, in the context of the greenhouse effect in a convective atmosphere.
Get NiV to make a direct unambiguous statement that he thinks back radiation results in increased surface temperature on earth. Then I’ll believe he thinks it does. But what he writes appears to say the exact opposite of what you claim he says.
Lucia,
Get NiV to make a direct unambiguous statement that he thinks back radiation results in increased surface temperature on earth.
You are changing the question.
NiV clearly says that GHG affect surface temperature: The gradient is controlled by adiabatic expansion/compression, and the intercept is controlled by insolation and by the average altitude of emission to space (which is affected by the concentration of GHGs).
It doesn’t get much clearly than that.
@ Lucia (100)
With all due respect, this is not helpful. Nullius doesn’t dispute that this is not real physics but it has all appearances of that. (I can guarantee that neither Eric or NYJ will ever figure it out on their own.) He wants us to find out where the ambush is. Calling it “Leprechaun physics” (or any other name) only shows that you know you are being tricked but you don’t seem to know what the problem is. Maybe this is not the best teaching technique (have you ever tried to figure out why a particularly clever design of perpetuum mobile won’t work? it is kind of similar sort of an exercise) especially in a blog environment but it’s not completely useless.
Either you have to point out what exactly is wrong with his construct in 49 or he could volunteer his solution. Then we could discuss it and, more importantly, figure out whether it’s really relevant to atmosphere, as he claims.
You are correct that back radiation affects surface temperature and I thought Nullius agreed with you in 71. But maybe he agreed with something else.
kd33
I do not believe I am changing the question.
Get NiV to state that backradiation affects the surface temperature explicitly. Not by mentioning intercept, but by saying that back radiation affect surface temperature, and more over, and increase in back radiation will change the surface temperature.
Saska
He wants us to find out where the ambush is.
There is no point in finding out where the ambush is when there is no ambush.
Either you have to point out what exactly is wrong with his construct in 49 or he could volunteer his solution.
I’ve pointed out numerous things wrong with it. So has Eric. Among other things, in that construct, NiV’s application of the 1st law of thermo is wrong, his claim that his explanation matches that for the atmosphere is incorrect.
I have suggested he sit down, write the heat balances and do the problem correctly. Also, that he review the explanation for the atmosphere so he can see that explanation doesn’t match the explanation in the atmosphere.
figure out whether it’s really relevant to atmosphere, as he claims.
It’s not. The model he describes– which might lead to some problem if it applies in solar pond, doesn’t apply in a solar pond and is not the model used to explain heat transfer in the atmosphere.
Sure. If what NiV describes in 49 applied, it might cause problems in a solar pond. But it doesn’t apply there, so it doesn’t cause problems. That physical model also isn’t claimed to explain the atmosphere– not even approximately. So what’s the point of talking about the possibility of weird results in a hypothetical model no one thinks describes the atmosphere and which no one thinks describes solar ponds. (Answer: there is no point.)
I thought Nullius agreed with you in 71. But maybe he agreed with something else.
NiV seems to be agreeing with something I said in a long response to Bob. But I don’t know what he agrees with.
Lucia,
I don’t know about numerous times. Perhaps I missed something. The only one that I remember is that in (82) you objected that “the topmost slab of water is in contact air”. Nullius tried to explain in (87) that this is not important. (What he meant is that if you get X from the Sun and lose X/2 to convection/evaporation then to balance the energy you need to send up another X/2 in long waves. Then, by isotropy, you are sending the same X/2 downward and his whole story of (49) repeats.) In your rebuttal in (93) you are focusing too much on the solar pond as an engineering product as opposed to solar pond as physical model. Nullius is not interested in transient behavior, nor in the industrial operation. He wants a steady state where the incoming flux (or a portion thereof) is balanced by the outgoing IR. This is a completely legitimate gedankenexperiment and I don’t believe you ever pointed out anything terminally wrong with it.
Sashka-
He wants a steady state where the incoming flux (or a portion thereof) is balanced by the outgoing IR.
If you mean incoming radiative flux , it is not balanced by outgoing IR at steady state.
It’s appears NiV is making claims about radiative flux because he writes things like this
We take the topmost slab of water just thick enough to be opaque. It radiates X units of radiation upwards, to match the power from the sun, and being isotropic radiates the same X units down. It’s losing 2X units of power, so it must receive 2X units to balance it (or cool and thus radiate less). The only place it can get this is from the layer below, so the layer below must be radiating 2X upwards, 2X downwards, and be considerably warmer to be able to do so. The layer below that radiates 3X up and down, below that 4X, 5X, and so on to the bottom of the pond.
To repeat: this is is wrong at steady state in a real, honest to goodness solar because radiative fluxes don’t balance in a pond. band because it is not balanced by outgoing IR at steady state.
This is a completely legitimate gedankenexperiment and I don’t believe you ever pointed out anything terminally wrong with it.
NiV’s application of conservation of energy is incorrect– even if he is assuming steady state. This is because he is neglecting conduction and convection in his discussion of energy balance balance. Both occur in both the atmosphere and the solar pond. He also claims that his sort of layer model is used by climatologists to explain back radiation. That claim is also incorrect.
(He has also made other errors in specifying boundary conditions. Those involve mis-applying conservation of energy. )
“Real” solar ponds are engineered. If operated at steady state heat is removed from the bottom. If NiV is going to suggest something doesn’t happen in real solar ponds and ask why it doesn’t, we need to discuss a physical model that actually makes sense for a solar pond.
There’s a lot to deal with here! I’ll try to be brief.
#89, I agree with your last sentence, and haven’t suggested otherwise.
#90, You are both wrong and I am correct! Heh.
#91, You say nobody believes in a pure radiative model. I’ve met lots of people who believe in a pure radiative model, because that’s all they’ve been told about, because that’s what almost all the presentations in schools and to the public say. Sunlight warms the ground, it radiates infra-red, which gets trapped by greenhouse gases, and they radiate it back to the surface. That’s it. That’s the theory. And they say that anyone who denies such basic physics has to be either grossly ignorant or dishonest.
The pure radiative model is also the reason for the emphasis on back radiation in explanations at the higher levels. In the pure radiative case, back radiation is the reason for the warming. In the convective-radiative case, it is not. By taking the pure radiative model as the basic mechanism, explaining back radiation, and then adding on convection as an afterthought, the misunderstanding is perfectly understandable.
It’s like taking the temperature of a pot of water boiling vigorously on a stove and asking why it is exactly 100 C. The answer offered is that it is because the pot lid reflects heat back to the surface, raising its temperature to precisely 100 C. It’s quite true that pot lids do trap heat, I’m not saying they don’t, but the cause of the temperature being what it is is that 100 C is the boiling point of water. Once you get to 100 C – or once you get to the adiabatic lapse rate – all the other details cease to matter. The fact the water is boiling is not just a minor correction to the pot lid explanation.
#93, Radiation is propagating electromagnetic waves. I’m not misapplying the first law. I do know how to apply a heat balance. And your concern about the boundary conditions at the surface is not relevant to the point. Feel free to ascribe any temperature you like to it; the same problem occurs.
I agree that “in the general case for a solar pond with convection, conduction and radiation, the first law does not require radiation at each layer to increase arithmetically”, but the usual explanation of the greenhouse effect doesn’t include convection and conduction, they’re added on afterwards as small and unimportant corrections. In the case of the non-exploding water pond, it’s clearly a massive “correction”.
What I am claiming applies in the pond is claimed to apply in the atmosphere, until you point out the omission and then they say “oh, yes…”
And I have already said that the reason the pond doesn’t explode is because of convection. I’m well aware of it.
I do have several simple (and even complicated) climate text books. It’s up to you, of course, but I’d like to point out that I’m not treating you as an ignorant beginner just because you’ve misunderstood the physics. It helps the conversation enormously.
Incidentally, apart from the one paragraph I was talking about normal ponds, not solar ponds. A solar pond is one in which convection has been suppressed by introducing a halocline.
#94, I thought I mentioned the depth of the pool? A couple of metres.
#96, Your preconceptions are getting in the way of any objectivity.
#98, “they agree on the key point: do GHG change surface temperature” Yes. Agreed.
#99, “Do we agree that backradiation increases the surface temperature above what it would be without back radiation?” We agree that the surface temperature is increased above what it would be without back radiation, I don’t agree that back radiation causes it.
I’ll try asking some slightly different questions. Do we agree that the water in a pond absorbs and re-emits upwelling IR like a greenhouse gas and will therefore emit back radiation down towards the bottom? Do we agree that nevertheless, there is no greenhouse warming of the bottom in a pool of water? Do we therefore agree that back radiation does not necessarily result in warming? Can we get this far?
#103, Yes you’re changing the question. In 71, I was agreeing with everything in your reply to Bob.
#105, Thank you. That’s exactly right. Most of what I said referred to ordinary ponds, not solar ones.
106–
You say nobody believes in a pure radiative model. I’ve met lots of people who believe in a pure radiative model, because that’s all they’ve been told about, because that’s what almost all the presentations in schools and to the public say. Sunlight warms the ground, it radiates infra-red, which gets trapped by greenhouse gases, and they radiate it back to the surface. That’s it. That’s the theory.
Oddly enough, though expressed at it’s simplest this is not the layer model you described. I certainly believe lots of people don’t bother learning ever more detailed and correct models– but what you say is not evidence that anyone (or much of anyone) believes the model you claim they believe.
Your pure radiation layer model model is manifestly not the prevailing 1-d simplification. The radiative-convective model is.
#99, “Do we agree that backradiation increases the surface temperature above what it would be without back radiation?” We agree that the surface temperature is increased above what it would be without back radiation, I don’t agree that back radiation causes it.
Ok. I have no idea what you mean then.
I’m not going to engage in an argument where you attempt shift the entire burden of making points to me by asking questions. It’s one thing to ask someone questions aimed at justifying claims they actually made (e.g. what did you do to derive X). It’s something else entirely to just start throwing out stray questions. The latter is utterly disrespectful to other people’s time. If you want to know the transmissivity of water, you look it up.
105, Thank you. That’s exactly right. Most of what I said referred to ordinary ponds, not solar ones.
Many of the things you have written is mistaken for ordinary ponds, puddles and the ocean as well. For example: Your statements about what application of the first law of thermo requires for a layer inside the pond (solar or otherwise) and your statement about boundary conditions at the upper surface. However, you brought up the solar ponds notion. A few of the mistakes are unique to solar ponds– yet you still claimed them and linked them to solar ponds.
Optical Density
So…
The swimming pool illustrates that no matter how hard back radiation tries to impose a temperature gradient, convection acts to (very nearly) wipe that temperature gradient out.
Because water is incompressible, convection (very nearly) returns the tempreture gradient to zero. Because the atmosphere is compressible, convection (very nearly) returns the gradient to the ALR.
But, in addition to creating back-radiation, GHG also change the optical density of the atmosphere and so raises the characteristic emissions altitutde, hence increases surface temperature.
In this sense, back radiation does not cause the temperature increase because it’s effect is (very nearly) wiped out by convection. Rather it is the changing optical density that raises the CEA that causes the temperature increase.
Fascinating.
So much for the pith. Just the usual morass of people talking past each other. No wonder scientists came up with their publishing process.
#109,
Excellent summary!
I’ve enjoyed this discussion immensely (and thanks to everyone), but it’s a particular delight to hear from those who did manage to see what I mean, well enough to say it better and more concisely than I could.
NiV–
What you mean involves some distinction in your mind which makes no substantive difference to the answer “Does back radiation cause the surface to warm”. The answer is yes back radiation causes the surface to warm.
Once could also say “Changes in Optical Density result in back radiation, which causes the surface to warm. The surface warming changes the boundary condition at the surface and integrating up, we find the CEA rises to result in a emission balance at the top of the atmosphere.”
@ Lucia (105)
If you mean incoming radiative flux , it is not balanced by outgoing IR at steady state.
Right, but I said “or a portion thereof” which is sufficient for the argument.
#112,
And if you increase the back radiation considerably and no additional warming occurs, would you still believe the back radiation is the cause?
112–Why do you ask? What do you think the answer is?
113–@ Lucia (105)
I didn’t say you said it balanced. We were discussing what NiV claimed, and I quoted the text where he said outgoing was balanced.
This discussion is way too emotional. Maybe it is the mere mention of Christopher Monckton’s name that drives Warmists crazy.
May I recommend the “Science of Doom” where cooler heads prevail?
http://scienceofdoom.com/2011/09/22/measuring-climate-sensitivity-part-one/
#115, Why do you ask why I ask? Are you just avoiding the question now?
I think that even though back radiation is increased and no additional warming results, you will still claim that back radiation was the cause of the warming that didn’t occur, while insisting that I’m misusing physics to have suggested that more back radiation would result in any additional warming. You’ll say it’s nonsense to suggest that warming by back radiation is cancelled by convection, and the actual reason there’s no warming – contrary to my assertion that there is – is that I’ve neglected to account for convection in the heat balance equations.
And we’ll go round and round in circles forever more.
It’s been a delightful waltz, but I don’t have the heart to watch you dig any deeper. As the Valley Girls say:
Whatever.
It’s just the ‘skeptical’ cuckoos coming home to roost, KK.
KDK33 @109
“The swimming pool illustrates that no matter how hard back radiation tries to impose a temperature gradient, convection acts to (very nearly) wipe that temperature gradient out.”
The swimming pool analysis is totally incorrect. The mean free path of the LW radiation is so small, that radiation is not an important factor in the transmission of energy in water. Molecular motion and convection are the means of transport of energy. The dependence of emission on depth that was postulated in NiV’s analysis was wrong.
In addition, energy transport in a gas is much different from energy transport in a liquid, as I mentioned radiation is more significant because the mean free path for absorption can be many meters or infinite, depending on the wave length of the radiation.
“Because water is incompressible, convection (very nearly) returns the tempreture gradient to zero. Because the atmosphere is compressible, convection (very nearly) returns the gradient to the ALR.”
There is a temperature gradient in the oceans. The layer warmed by the sun’s radiation cannot transfer energy to the cooler layers below. However in the nightime, convection transfers energy to the top surface where it is radiated into the atmosphere by the surface skin layer.
The Lapse rate and the absorption and reemission of IR radiation is what is responsible for the reduction in heat loss due to GHG’s.
“But, in addition to creating back-radiation, GHG also change the optical density of the atmosphere and so raises the characteristic emissions altitutde, hence increases surface temperature.
In this sense, back radiation does not cause the temperature increase because it’s effect is (very nearly) wiped out by convection. Rather it is the changing optical density that raises the CEA that causes the temperature increase.”
This is a nonsense statement. The increase in optical density is a result of increased absorption and of IR by the GHGs. This increase in absorption is necessarily accompanied by an increase in emission. The downward emission is the back radiation.
“Fascinating.”
Yes indeed fascinating, and another highly amusing example of argument for the sake of argument, with no real point being made. It is clear that you don’t understand what optical density means.
It is interesting that the self appointed genius of this thread, NiV agrees. He is sorry that he couldn’t say things as clearly.
The Dunning Kruger effect strikes again.
Sure Eric, whatever.
#119,
It’s a very odd feeling talking to somebody who repeats back to you what you just said in different words as a way to prove you wrong.
“The mean free path of the LW radiation is so small, that radiation is not an important factor in the transmission of energy in water.”
The conventional greenhouse effect is based on having a short mean free path. The shorter the path, the harder it is for energy to escape by radiation, the more it is “trapped”, the more intense the greenhouse effect. You have basically said that I’m wrong because the greenhouse effect is too strong in water – which is itself exactly what I said.
“convection transfers energy to the top surface where it is radiated into the atmosphere by the surface skin layer.” Again, exactly what I said.
“The increase in optical density is a result of increased absorption and of IR by the GHGs. This increase in absorption is necessarily accompanied by an increase in emission. The downward emission is the back radiation.”
True. True. And true. And again, just what I’ve been saying. The point is that putting water on top increases the back radiation the surface receives, because of increased absorption of IR by the GHG water, and yet the temperature doesn’t rise at all because the extra heat is carried away by convection. That what I said in the first post, and what I’ve said repeatedly since.
You keep on repeating back to us stuff we already understand, and have already said, as if it was educational. I haven’t appointed myself a genius; as physics goes this is not even very difficult. The problem seems to be entirely to do with preconceptions. And of course the point about the Dunning-Kruger effect is that you wouldn’t know if you‘d got it.
On the whole, I don’t think you do. It’s not that you’re too stupid or uneducated to understand, you’ve expressed most of the essential elements of the physics yourself already. It’s that you’re so firmly fixed on the idea that I must be wrong, that you can’t put the pieces together in the right shape because that would lead to an unacceptable conclusion. You keep on trying to find wrong ways to put the pieces together that fit what I say, most of them backwards, so you can say that’s my mistake, and then countering that by repeating the same error.
The back radiation argument leads to the error in which the oceans boil. That’s the consequences of your own argument worked out, done to demonstrate the ridiculous conclusions it implies. It doesn’t happen because convection completely cancels the effect of the back radiation. It doesn’t cancel the back radiation itself – that’s stronger than ever – but the additional back radiation has no effect on the temperature in a convecting fluid.
You appear to agree with each part of my argument individually. You’ve just got to put them all together in the right order now.