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Tom Curtis at 09:26 AM on 18 July 2014Joseph E. Postma and the Greenhouse Effect
MA Rodger @130, diffuse reflection can come about either due the very irregular surfaces at the scale of the wavelength of the incident light, or through partial reflection of light of crystal (or other discrete) subsurfaces in a translucent object. Wikipedia illustrates the later process for a quartz like substance:
"Figure 1 – General mechanism of diffuse reflection by a solid surface (refraction phenomena not represented)"
The mechanism for diffuse reflection in snow and ice obviously follows the mechanism above. Water droplets (as in cloud or fog) also follow the mechanism, but only for light rays that strike at a high angle of incidence. Most photons with a low angle of incidence enter the droplets and are either absorbed in the droplet or reflected coherently by wavelength in the phenomenon which generates rainbows. The dependence on angle of incidence for the amount of diffuse reflection in droplets is why clouds with smaller droplet size also have higher albedo.
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Non-Scientist at 07:53 AM on 18 July 2014Rupert Murdoch doesn't understand climate change basics, and that's a problem
@foolonthehill, Lloyd, Jenna
Tx for the perspective.
I'm speaking not of all older people, hopefully not of most, but some I've known. I'm also speaking from personal experience, as I'm approaching that age and have a neurological disease, and am seeing bits of those qualities impinging on me. I try to adapt around them, but as it is with climate, one can't entirely outrun Nature.
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MA Rodger at 05:10 AM on 18 July 2014Joseph E. Postma and the Greenhouse Effect
Tom Curtis @126.
To be more exact about reflection of light, the light from the mountain top or wherever is the result of 'defuse' reflection rather than the mirror-like 'specular' reflection. My understanding of defuse reflection is that it is a lot more complex than simply photons bouncing off the various features of a rough surface/subsurface and can involve a photon being absorbed followed very closely by a newly created photon of the same wavelength being emitted. How important/common the various mechanisms of defuse reflection I know not. -
kampmannpeine at 03:18 AM on 18 July 2014Rupert Murdoch doesn't understand climate change basics, and that's a problem
It is always the same:
if you are claiming something, you have the burden of proof.
I just came about an atheist homepage (myself not being one :) ) - the same arguments from the believers ...http://atheism.about.com/od/doesgodexist/a/burdenofproof.htm
it seems to be a similar kind of epistemological discussion ...
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KR at 02:27 AM on 18 July 2014Joseph E. Postma and the Greenhouse Effect
MA Rodger - You're quite correct, reflection is something else entirely.
As an emissivity/warming test, how about the following. Open your freezer, stand back a meter or two (outside any convection), and hold your hand up towards it. Your hand will feel cool. Turn your hand towards the rest of the room, it will feel somewhat warmer.
Nothing has changed with convection/conduction, but the radiated IR from the kitchen, despite the kitchen being cooler than your hand/body, is higher than that from the freezer. An object cooler than your hand has warmed it.
Again, the starting point for radiative energy input to an object is zero - any outside object warmer than absolute zero will radiate some energy towards it, increasing the input energy flow, and warming it until outgoing energy matches incoming. Cool objects warm nearby warmer ones relative to there being no object there are all.
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CBDunkerson at 02:12 AM on 18 July 2014Joseph E. Postma and the Greenhouse Effect
Tom wrote: "Rather, he has said that any photons emitted by the colder object will carry less energy to the warmer object than the photons emitted by the warm object will carry to the cold object."
I don't think that interpretation of Postma's position is possible/accurate unless you change "less energy" to "no energy". It seems very clear that he doesn't believe a colder object can 'heat' a warmer object at all. Transferring "less energy" per photon would still result in the colder object giving the warmer object a higher temperature than it would have if the colder object were not there at all... which is contrary to Postma's position. As he put it;
"It can be misinterpreted by inferring that a cold source can heat a warmer source."
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Dikran Marsupial at 00:47 AM on 18 July 2014Joseph E. Postma and the Greenhouse Effect
Tom wrote "Rather, he has said that any photons emitted by the colder object will carry less energy to the warmer object than the photons emitted by the warm object will carry to the cold object."
I think that is a rather charitable interpretation (which is in general what I would recommend) of what he has actually written (but not what I would recommend if the exercise was to clarify exactly what he was saying). However in that case he would be consistent with modern statistical intepretations of thermodynamics, in which case there is no problem with backradiation warming the surface (relative to the temperature it would assume in the absence of backradiation). It is a pity that he refused to give direct answers to direct questions (without being obstructive). If he had, we would already have resolved this by now. His loss entirely.
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Tom Curtis at 00:36 AM on 18 July 2014Joseph E. Postma and the Greenhouse Effect
MA Rodger @124, when light is reflected of an object, it is not absorbed and then rapidly re-emitted. Rather it is not absorbed at all, merely reflected, and hence contains practically zero information about the temperature of the reflecting object. Nor has Postma said that no photons will travel from the colder to the warmer object. Rather, he has said that any photons emitted by the colder object will carry less energy to the warmer object than the photons emitted by the warm object will carry to the cold object.
He might have said it clearer, but that is what he has said.
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Dikran Marsupial at 00:22 AM on 18 July 2014Joseph E. Postma and the Greenhouse Effect
MA Roger, I agree, however wrapping a satellite in multiple layer insulation might be though.
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MA Rodger at 00:11 AM on 18 July 2014Joseph E. Postma and the Greenhouse Effect
I have been assuming that when, for instance, the early morning sun illuminates a distant icy peak, the radiation by which I see it is reflected from its frosted summit - that is absorbed but then re-emitted before it has a chance to boost the thermal content of the ice. Thus in allowing my eye to detect the mountain, it is not in any way resultant from the temperature of the cold mountain top (relative to the temperature inside my eyeball). Contrary to comment @ 110 & @109/123, I therefore do not consider seeing cold objects as adding to the evidence that JPostma (?or devon) is wrong.
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One Planet Only Forever at 23:55 PM on 17 July 2014Rupert Murdoch doesn't understand climate change basics, and that's a problem
John @34,
When you consider the following:
- there are many other damaging impacts, and risks of significant damage, from all the activities related to the burning of fossil fuels, not just the creation of excess CO2
- fossil fuels will only be less and less available for everyone to benefit from because they are a finite resource. The easiest to get has already been used up.
- There has been violent conflict as powerful people have others people fight for their opportunity to win more of the opportunity to benefit. There will be even more violent conflict as the resource dwindles and more people want more of the benefit.
It would seem irrational for anyone to disagree with curtailing the opportunity for anyone, especially an already wealthy person, to benefit from such a damaging unsustainable activity.
And yet there is fierce opposition to such a rational development toward a sustainable better future for all.
That can be best explained by the developed nations developing in a way that created a strong motivation for people to care more about getting the best present they can for themselves any way they can get away with, rather than striving to develop a sustainable better future for all life on this amazing planet. People with that attitude only support something they personally expect to benefit from. Some will try to claim it is basic human nature, but altruism and desiring to help others are also basic human nature. And those people will be very biased in the information gathering and learning. They will only accept what is in their interest.
The persistent arguments against protecting the future from disrupted climate change due to callous unacceptable human activity proves how damaging and dangerous and ultimately unsustainable the developed system has become. It is clear that the system developed in the developed nations promotes callousness and discourages altruism. It is that system, promoted by the likes of Murdoch (who fight for more people to demand the freedom to do whatever damaging unhelpful thing they please), that must change. Then, and only then, will there be real action to stop the unacceptable pursuits of those among us who only care about themselves.
Some people will never change their mind. And the popularity of unacceptable things can be prolonged, but cannot be indefinitely sustained. The future of humanity requires development of societies that do not allow selfish people to feel justified and emboldened. It requires societies where such people constantly fail quickly and are endlessly disappointed, even if it makes them angry, even if it means they are being "kept from having the freedom to do as they please". The only freedom for such people needs to be the freedom to change their mind.
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CBDunkerson at 22:58 PM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
devon wrote: "I beleive that J Postma HAS made a valid point here and more than adequately addressed the question."
Yep. That's why the Earth is shrouded in perpetual darkness. After all, photons can't possibly travel from space, which is cold, to the Earth's atmosphere, which is warmer. There is no sunlight. It does not warm the Earth. Can't happen.
Either that or what you believe to be "a valid point" is instead, obviously wrong.
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chriskoz at 22:39 PM on 17 July 2014Atlas of Mortality and Economic Losses from Weather, Climate and Water Extremes
The most important detail in that atlas worth special attention (not mentioned in this article) is the statistcs of the number of events reported broken up to 4 decades of the timespan considered, then further broken up into continents.
Although related casualty $ damage statistics vary wildly (e.g. in Africa, interestingly, the $ dropped to near *zero* in last two decades), the event number statistics are unmistakeable: steadily rising each decade both globaly and in each continent. In most continents the rise seams linear but in Afrika it's exponentisially doubling every decade!
How much of this remarkable rise can be explained by better reporting and increased population density since 1970? Certainly not all, although it's not easy to say exactly. However such ubiquitous rise, including in areas where population didn't change significantly (Europe), indicates strongly that AGW factor (increased energy in weather systems) is at play here.
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John Michael Carter at 19:33 PM on 17 July 2014Rupert Murdoch doesn't understand climate change basics, and that's a problem
I don't think that most people know the basics of climate change.
I saw a few comments that implied it was inexcusable, but I think the readership here (Ive already linked over a few times now because I know the quality is always solid) is far more knowledgeable. I also think making it mainly about specific future temperature changes, which is semi speculation, makes it easy for people to think that it "wont come to pass," and also doesnt really convey any sense of what is REALLY really going on, and when people know what is really going on, then they are far more connected to the issue (and understand it far better,something drastically lacking today,and desperately needed for desperately needed improved assessment. I mean most politicians in America don't even really understand the issue well.)
I really don't see the basics of the issue expressed much at all. I tried to give what I think is "really the problem," and the basics, regardless of modeling. I do know that when I've actually conversed with people, almost no one knows this basic stuff, and unless they are super extreme politically, they are usually surprised, more concerned,and usually shift their view on CC a little bit. (In person anyway, online its wildly polarized and polarizing, and all the condescension, and even unnecessary if mild misreprsentation or, more often, dismssal on some of the "have the issue correct" sites, of the "have the issue incorrect" sites and people who are misled on them, etc, doesn't help make the basic near incontrovertible case, and immediatley loses the one audiecne that is needed to actually increase knowledge rather than just self reinforce. It makes people very defensive and then even more blindly adherent to proving theyre right no matter what. (extreme examples of such adherence being wuttsupwthat, where the intense level of hifalutin prose, mangled context and equations along with clearly genuine belief in their special "smarter than everybody else" insider knowledge that climate scientists are quacks, is inversely proportional to their actual knowledge on the basics of the issue)
I also strongly think that calling this issue climate change - regardless of possibly setting up fuel for more far right gimmickery that "the AGW crowd" is "changing the name because the facts aren't working" - has really added to major confusion on and misunderstanding of the issue. (Remember, most of America for example, and Australia does not have the knowledge of a lot of readers of this site.) It causes people to conflate what is observable right now as climate with the actual problem, when it's not remotely. ) I try to explain here why the CC moniker does that. I think it's a pretty coherent case.
Re Murdoch's tragedy of the commons argument, it's a decent one and genuinely made all over the place, yet flawed, but rarely affectively addressed. Here, anyway. For the majority of mankind's modern cc gg emissions period, the U.S. dominated the world in total emissions, at one point responsble for an entire quarter of global emissions? (Or something.) The U.S. is still the global power/world leader. Between that fact and that the U.S. has been the huge world leader on causing the problem in the first place, sensible U.S. action and leadership on the issue by both example and simultaneous and ongoing advocation to other countries will make it very easy for other countries to follow. Not as strong an argument for Australia, but given the level of misino their I can't see why Australia couldnt workin concert with the U.S on this, and make the above case even stronger. (If Australia gets us in, suddenly that argument that doing something in Australia is not worth it, flies out the window.)
I have a concise remediation plan (for the actual climate problem, not the misinformation problem keeping us for even effectively assessing the climate problem), that maximizes results, minimizes costs, maximizes efficiency, minimizes government, meets or beats many ideologically driven impediments to open mindedness on the issue. And, it also mentions the key leadership role of the U.S., so that it's not immediately assumed doing something in the U.S at least won't have much of an affect worldwide. I'd link to it as well but have enough links in this post; its on my blog, posted today.
Moderator Response:[JH] Words written in "all caps" constitute shouting and are therefore prohibited by the SkS Comments Policy. Please read the Comments Policy and adhere to it.
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Dikran Marsupial at 19:23 PM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
Devon, I supplied the example you requested; I am willing to go through the physics with you, provided you are willing to adopt the "Socratic method" (i.e. being willing to promptly give direct answers to direct questons).
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Dikran Marsupial at 19:19 PM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
Tom, The misunderstanding that you suggest Postma was labering under is not reasonable as the initial question clearly stated that the iron had equilibriated wuth the furnace prior to the furnace being switched off.
Time passes and the iron is soaked in the furnace and the furnace is then switched off, now quickly becoming cooler than the hot iron. [emphasis mine]
I also addressed this possible misunderstanding as soon as there was clear evidence that it might be the problem, i.e. in the very first reply to the post you mention
you say "somehow" as if to suggest this is an unlikely scenario. It clearly isn't. The iron in the furnace (as we are discussing radiative transfer) is likely to be insulated (if only by a vacuum) from the body of the furnace, so if the body of the furnace is cooled after the iron has equilibriated with it, then of course the iron will cool more slowly.
Tom writes:
There is a bit more argy bargy, but by his post @88, I think Postma has clearly answered your question. Specifically, he writes:
"'A' emits photons in all directions...."
The problem with this answer is that it does not mention object B and hence is open to equivocation later in a way that the answer "yes" is not. "YES" is only three characters, so why would Postma go to the extra effort writing 34, if not to be deliberately obstructive? BTW, if you notice post 88 was quite a long way into the discussion of that very basic question, and I had already lost patience with his continual obfuscation, as demonstrated by my reply. Giving what you think is an unambiguous answer, after so much obfuscation, in no way excuses JPostma's behaviour, or warrants me continuing the discussion.
Giving "yes" and "no" answers is also hardly "parroting terms"!
As to the effectiveness of Socratic methods. Firstly when your interloqutor is being deliberately obfuscatory (as is the case here e.g. "the lump of iron radiates what is required of it"), it is not at all unreasonable to require that questions be given a "yes" or "no" answer if they are deliberately framed to elicit an answer of that form, and the good reasons for doing so clearly explained.
Secondly, Socratic method is an excellent method for seeking scientific truth, provided that is what both parties are actually seeking. Its use here has provided a definite indication that Postma is not seeking scientific truth, which suggests any form of scientific dialogue is likely to prove unfruitful.
It is a shame that Postma was not willing to engage in a Socratic dialogue, as it would have provided him with the most direct route to proving that I am wrong (should such a route exist, being a scientists myself, I do not deny the existence of such a route a-priori, and actively want to be shown it should it exist).
JPostma has gone some way in showing that his views are not quite as bizarre as those of some who cite the second law of thermodynamics as an objection to the EGHE, in that he suggested that cooler objects do emit photons that strike warmer ones. However getting to that point was like getting blood out of a stone, and it left me without the enthusiasm required to get him to clearly state the answer to the next question. Life is too short, someone either is interested in communicating their scientific ideas and having them scrutinised, or they are not. JPostma is in the latter category.
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chriskoz at 19:10 PM on 17 July 2014Rupert Murdoch doesn't understand climate change basics, and that's a problem
mrkt@32,
I think your observation is not explained by Non-Scientist@1 perception but by the fact older people (espacially over 70 as in your sample) who are selfish/childless and don't care about ruining the environment for future generations; they don't bother pursuing the scientific news about an issue which almost certainly won't afect their lifetime. On the other hand, people of the same profile (i.e. selfish/childless) but young (say 20-30s, who look forward to living well into the second half of this century), do know that the issue is predicted to affect them, therefore they have strong incentive pursueing the science explaining it.
So, IMO, the failure by our civilisation to develop responsible intergenerational ethics can be the cause behind the fact that older people are more likely to deny the seriousness of AGW. The new information absorbsion is not an issue, because siad information is very simple: it follows from basic physics from primary school and I don't believe even people of Rupert's age can forget such basics. And even if some do forget, they can still try to relearn if they have right attitude - e.g. responsible intergenerational ethics are enrooted in their principles - but if their principles are opposite, the easiest attitude is to recede into denial.
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devon at 18:48 PM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
I beleive that J Postma HAS has made a valid point here and more than adequately addressed the question.
Moderator Response:[JH] Words written in "all caps" constitute shouting and are therefore prohibited by the SkS Comments Policy. Please read the Comments Policy and adhere to it.
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MA Rodger at 18:46 PM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
As JPostma appears more comfortable with mathematical formulae, would it be worth restating Robert Murphy's question @107 in the manner below. The statement of JPostma @67 strongly suggests that he is happy wiith the final equation derived below. Thus the question is whether he agrees with its derevation as presented here.
Net energy flow from black body A with temperature TA to black body B with temperature TB = Energy flow from A to B minus Energy flow from B to A.
Energy flow from A to B = XσTA4
Energy flow from B to A = XσTB4Where
X = a system constant.
σ = Stefan-Boltzmann constantTherefore:
Net Energy flow from A to B = Xσ(TA4 - TB4) -
Tom Curtis at 18:02 PM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
Dikran, referring back to MA Rodger's original question @52, Postma appears to have interpreted the scenario claiming that, at the time when the furnace was turned of, the temperature of the Furnace was T(F) and that of the iron was T(i), such that T(i) < T(F), then at some later stage the iron will heat the furnace such that the furnace rises to a temperature greater than T(F), which he correctly claims is impossible, but which entirely misses the point.
Having a look through the exchange, by his post @64, he finely states his response in a way that makes it clear that is what he is denying (ie, that the temperatur of the furnace is ever raised above the point it had at the time of switching of), and clearly acknowledges that the iron will slow down the cooling of the furnace.
@67, he is clearly evasive when he writes:
"The question as to "when" the iron starts to radiate was what was precisely set up as the strawman. If you truly require me to answer "when" the iron starts to radiate, it is troublesome. But the answer is obvious, it has been stated, and the answer is specified directly in the heat flow equation here, and also by the simple understanding of heat flow and the ability to attain equilibrium."
It is clearly not troublesome as to when the iron will begin to radiate, for it always radiates (as does any object warmer than 0 degrees K). Thus the iron begins to radiate when it first got seperated from the ore. Postma provides an equivalent answer @70, saying,
"... it is precisely clear when the iron radiates. It couldn't be any more clear. I am sorry if it is not clear to you. The answer is "as soon as the iron has a temperature"."
There is a bit more argy bargy, but by his post @88, I think Postma has clearly answered your question. Specifically, he writes:
"'A' emits photons in all directions. However, emission from 'A' does not heat a warmer object, as the heat flow equation shows that heating only occurs from hot to cold."
That of course is correct, because it is the balance of energy transfer that determines the flow of heat, ie, net energy transfer, a point Postma had conceded still earlier. In the Socratic method, you cannot expect your opposite to simply parrot your terms, and at that point you shoud have IMO moved on to the next point.
To be honest, I do not think there is anything to be gained by Socratic method with Postma in any event. He has already demonstrated a willingness to state flatly contradictory views and rely obscurity to cloak himself with a semblence of reason in lieu of the actuality. Therefore an attempted Socratic method will be a strictly circular excercise.
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Tom Curtis at 17:16 PM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
A small, but important correction to my comment @114. Where I say, "Where it combines the light from two distinct black bodies, the entropy will be the energy weighted average of the entropies of the two black bodies", the entropies should be summed, rather than the average taken.
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Dikran Marsupial at 16:24 PM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
Devon wrote "Could anyone give a real life example of cold heating hot, or energy being created from nothing as the K&T energy budgets suggest."
The K&T energy budgets do not reuire energy being created from nothing, nor do they involve cold heating hot. If you think they do, then you are labouring under a misapprehension. I'd be happy to walk through the physics with you, provided you are willing (unlike JPostma) to give direct answers to direct questions, unambiguously signalling your agreement or otherwise with each step. Are you willing to do this, yes or no?
As for a cool object causing a warm object to become warmer, consider a satellite with a thorium reactor providing an internal heat source. Being in a vacuum, it can only loose heat radiatively and will reach an equilibrium temperature where radiative losses balance the heat generated by the reactor. Call this equilibrium temperature T. Now enclose the satellite in a black plastic sphere, that touches the satellite nowhere. Some of the heat radiated by the satellite will warm the sphere, which will in turn radiate some of it back towards the satellite, which will then warm to a new equilibrium temperature that is higher than T. This is true, even though the plastic sphere will be cooler than the satellite.
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WRyan at 13:09 PM on 17 July 2014El Niño in 2014: Still On the Way?
@OPOF
Thank you for the reply but I was already aware of the basics. The question I have is, "how does the warm ocean water transfer thermal energy to the air above it?"
I believe that the main method of thermal energy transfer is via Method 4 as described in my first post - "increased evaporation leads to increased humidity, which leads to increased cloud formaton, with the extra warming due to latent energy liberated from the phase transition as gaseous water vapour condenses to form liquid water droplets in clouds." But I don't know if that is actually true.
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Tom Curtis at 11:57 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
JPostma @51 writes in response to my post @50:
" "sufficient to emit greater energy at source than is recieve by incident radiation on the device"
That violates the first law of thermodynamics, and though I've refrained from engaging in the type of ad-hominem attack continually thrown my way, a statement like this really does expose scientific incompetency and a clutching of straws. I do apologize for having to make that remark, but alas, it couldn't be passed over in kindness, this time. Those preeminent experimentalists did not indeed interpret that their apparatus was magically producing more energy than received, ostensibly finding an exception to the 1st Law of thermodynamics. They would have laughed at that. What they found is that they could get sunlight to induce its maximum temperature on a plane, a temperature which is well above +100C. It is not an unexpected result."
(Initial quote italicized for clarity.)
I will concede that my thought was poorly expressed so that it could be misunderstood. Allow me to clarrify.
The de Saussure hot box consisted of an insulated box painted black in the interior, above which were mounted two or more glass panels to allow in sunlight but trap heat (both convective or radiant):
It should be noted that the addition of more than one glass panel in no way improves the traping of heat escape by convection. One panel is sufficient to stop the mixing of the gasses from inside and outside the box, and hence to stop the convective transfer of heat from inside to outside the box. It does, however, improve the traping of heat both by radiant transfer and by conduction through the glass. In doing so, it brings the hotbox model closer to a model of the atmospheric greenhouse effect, in that no energy escapes to space by either conduction or convection.
Using de Saussure hot boxes, de Saussure measured temperatures as high as 383 K, and John Herschel measured temperatures as high as 388.5 K, in the interior most comparment of the device. The did so in regions where (due to latitude) peak surface insolation was almost certainly less than 1100 W/m^2, and probably less than 1000 W/m^2. However, the black body radiation for 383 K radiates 1220 W/m^2, while at 388.5 K it radiates 1291.7 W/m^2. That is, at the "source" (ie, the interior of the innermost compartment of the device), the energy radiated by black body radiation was at least 100 W/m^2 (9%) greater than the "incident radiation on the device" (ie, the solar energy falling on uppermost panel of glass).
Postma does not like the result, so he disputes the written record (and in de Saussure's case, publicly demonstrated in London and Paris) of two of the foremost experimental scientists of their day as "anecdotal". Consequently I refer to a recent test of a single panel hot box (solar cooker) in Jordan:
The "black coated, fixed" cooker is the one most analogous to a de Saussure hot box. As can be seen, the average peak temperature over three days measurements achieved in the water in the black kettle within the box was 341.4 K. The equivalent black body radiation was 770.2 W/m^2. In contrast, the peak insolation recorded on any day during the experiment was was 717.4 W/m^2, and the insolation at the 14th hour (ie, the time of peak temperature) was just 364.5 W/m^2, less than half of the black body energy of the water. Without water to act as thermal ballast, the interior temperature of the hot box would have peaked earlier and time, and been greater than that recorded.
The obvious conclusion is that the interior temperatures in de Saussure hot boxes can easily be high enough that the interior black body emission from the inner most compartment exceeds in energy that of the incident sunlight. Postma says that this is impossible. Indeed, it is essential to his claims that this is impossible. It cannot be explained by the prevention of convection, and nor (given the high thermal conductivity of glass) can it be explained by insulation against conduction through the glass. That means any explanation of the increased temperature must include a greenhouse effect.
To illustrate this point, consider two hot box designs:
The first hot box is sealed by a panel that is transparent to both visible and IR light, but impermiable to air. Because it is impermiable to air, it prevents any mixing of external with internal air, and hence any escape of heat by convection. Because it is transparent to IR light, it neither absorbs nor radiates IR light. Therefore any IR radiation leaving the box must come from the floor of the box, as illustrated in (1) above.
The second hot box is sealed by a panel that is transparent to visible light, but absorbs IR light perfectly (emissivity = 1 for IR). Because it absorbs all IR radiation that falls on it, any IR radiaton from the floor of the box is absorbed by it. Because absorptivity equals emissivity, that means that energy is then reradiated, with half of it going up, and half of it going down, back into the box, as illustrated in (2) above.
Now enter the laws of thermodynamics. In particular, in this context the first law states that for any horizontal line drawn through a "box" above (horizontal plane for actual 3 D boxes), the energy going up equals the energy going down. That is, 1U = 1D, 2u = 2D, 2u = 2d, and 2U = 2D + 2d = 2 x 2D. (Note: 1U is energy flux U for box 1, etc. It is not 1 x U.)
Further, the second law of thermodynamics states that for each such horizontal line, the entropy of the energy going up will not be less than the entropy of the energy going down. Entropy, however, is the energy divided by the temperature. The temperature of the light for black body radiation is just the temperature of the black body that emitted it. Where it combines the light from two distinct black bodies, the entropy will be the energy weighted average of the entropies of the two black bodies.
So, let's assume that 1D = 2D equals 1100 W/m^2. Let us also assume the boxes are cubes with dimensions of 1 meter per side. Then the temperature of the base of box 1 equals 373.2 K (~100 C), and the entropy of 1U = 1100/373.2 = 2.95 J/K. In constrast, the black body emitting 1D was the Sun, with a surface temperature of approximately 5,750 K. Consequently the entropy of 1D is 0.2 J/K, and as required the entropy of all downward energy at a given distance above the bottom of the box is less than the entropy of all upward energy at the same distance. Indeed, the temperature of the bottom of the box would have to reach 5,750 K for that to not be the case - something it cannot do because of the first law of thermodynamics.
In the second box, the temperature of the panel is also 373.2 K, and hence the entropy of 2u is 2.95 J/K. The temperature of the base of box 2, however, rises to 443.8 K (~170 C). The upward power from that base (2U) equals 2200 W/m^2. The entropy of that energy is, therefore, 4.96 J/K. That is comfortably greater than that of both 2D and 2d(=2u), and certainly greater than their combined entropy of 1.57 J/K. Therefore the 2nd law of thermodynamics cannot forbid a situation such as illustrated in box 2, and the first law requires that the temperature of the floor of the box be 1.19 times greater than the temperature of the panel.
(Postma, and others of similar belief, appear to confuse themselves by using imprecise statements of the 2nd law, to the effect that no body can be gain heat from a cooler body. Heat, however, is net energy transfer. In box 2, the floor of the box (443.8 K) gains heat from the Sun (5,750 K). It then transfers heat to the panel (373.2 K). There is energy flow from the panel to the floor, but the energy flow from the floor to the panel, so the net energy flow (heat flow) is from the floor to the panel. This means that the floor is heated by the Sun, not the panel; but the floor is heated more by the Sun than it would be without the panel. There are no entropy considerations preventing this unless the floor approaches temperatures near to that of the Sun's surface.)
The important thing to note, however, is that mere prevention of convection cannot heat the floor more than sufficient to have a black body radiation equal in power to the incident radiation. Neither can prevention of conduction where radiant heat can escape, as in the examples above, conduction is considered to be zero in both boxes. Adding conduction can cool the floor temperature, but it cannot increase it in either case. Therefore floor temperatures greater than the black body temperature for the power of incident solar radiation is proof that a greenhouse effect is in operation. And just such temperatures have been observed historically by de Saussure and John Herschel, and more recently in testing of solar ovens.
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One Planet Only Forever at 11:21 AM on 17 July 2014El Niño in 2014: Still On the Way?
The basics of how El Nino temporarily increases the global average and La Nina temporarily reduces the global average is the air circulation above the water surface is warmed above warmer water and cooled above cooler water:
- when the ENSO is neutral, between the two, the global average could be said to not be influenced by the ENSO condition.
- when the ENSO has shifterd toward El Nino there is a larger area of warmer surface waters which results in warmer air above it that winds can carry to other regions beyond the area of warmer water.
- when the ENSO has shifterd toward La Nina there is a larger area of cooler surface waters which results in cooler air above it that winds can carry to other regions beyond the area of cooler water.
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Leto at 11:14 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
The posts by Postma and Devon raise the extraordinary image of a photon looking ahead along its path, measuring the temperature (or perhaps heat content) of the object it would strike, and then deciding retrospectively not to be emitted.
I can see why Postma might not want to make his views too explicit.
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mrkt at 10:14 AM on 17 July 2014Rupert Murdoch doesn't understand climate change basics, and that's a problem
Just a brief comment on the age question. I was interested in who were the signers of the OISM petition in my state (Arkansas, USA) and did a brief search on a few. Found ages for 50 (of 147 in the state). The average age was 73. Non-Scientist (@1) perception has some basis. On the other hand the average age at my Sierra club meeting last night was not much lower and these are not among the deniers.
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mancan18 at 09:50 AM on 17 July 2014Rupert Murdoch doesn't understand climate change basics, and that's a problem
Australia is about to repeal the carbon tax and stop the introduction of an ETS and, instead, is preparing to introduce a process called "direct" action, a marketing exercise designed to placate voters concerned about climate change by pretending that you can act on climate change by burning more coal. Australia doing this makes it the first "developed" nation to undo the market mechanism that has been widely advised by economists as the most efficient method to transform an economy from a high emissions economy to a low emissions economy.
In Australia, the main reason this has happened is the Murdoch press, which reaches about 83% of the reading public, taking a politically conservative editorial position and prominent anti-global warming stance. The other reason, I believe, is Australia's love of sport and its pub (going to a public bar in a hotel) culture. Many Australians, like everyone else, spend most of their time working and prefer to relax with their families, follow sport and socialise at a pub or club. They spend little of their relaxation time, which is valuable to them and rightly so, reading well researched articles about climate change, and get most of their climate change information from their most convenient source, a Murdoch controlled newspaper. Because many Australians read Murdoch newspapers for the sports reporting rather than the political commentary, the only political commentary many Australians get is from Murdoch newspapers. Because they feature three of Australia's most prominent conservative political commentators Andrew Bolt, Piers Ackerman and Miranda Devine, your average Australian gets a constant stream of climate change and global warming denial, which is reinforced by conservative shock-jocks on radio like Alan Jones and Ray Hadley. This narrative then drives the climate change debate in Australia's pub/club culture. This means the climate change narrative for most Australians is one of denial. Below the surface, there are many Australians who are concerned about climate change and do spend time researching the issue properly.
Whether, this will be enough, to overcome the political hiatus, remains to be seen. It seems even events like record temperatures for record times over wide areas, disastrious bushfires in October and an unprecedented flood washing cars down the main street of a rural country town, doesn't seem to register with people as, perhaps, something to do with climate change. It is just seen as more of the historical "bushfires and flooding rains" nature of Australia. -
pschopf at 08:58 AM on 17 July 2014Atlas of Mortality and Economic Losses from Weather, Climate and Water Extremes
Small point: The WMO is the World Meteorological Organization - not Association.
Moderator Response:[JH] My bad. Fixed. Thank you.
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DSL at 08:35 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
And again, Devon, the question Postma refused to answer: is the energy being radiated from Object A (at 10C) absorbed by Object B (at 50C)?
As soon as we start talking about "heat," the discussion gets silly. The term "heat" needs to be described in terms of energy exchange. The term "net" needs to be incorporated. The rhetorical ploy is to try to push the "argument" into terms that the general public understands: "cold things don't warm hot things." The reality is that all things absorb/emit radiation. That is, "all things exchange energy." Thus, cold things do indeed supply energy to warm things, but the warm things get rid of more energy than they absorb.
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DSL at 08:29 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
Devon, do all things above absolute zero radiate?
If so, then all such things are both emitting and absorbing radiated energy. "Cold" things emit less energy than "hot" things, but all things are relative, and all things absorb energy.
A block of ice is radiating energy (else you wouldn't be able to see it). A block of red hot iron is radiating. Put the two in the same room. Now put an identical block of red hot iron in an identical room but without the ice. Which block of iron cools down more rapidly?
It's not that the room is heating the iron above its initial temperature. Rather, it is decreasing the cooling efficiency of the iron relative to the situation with the block of ice.
In the same way, the atmosphere is absorbing energy radiated by the surface. Some of that radiation is then radiated downward, back to the surface. The surface is not a static energy source (well, the geothermal component is, but it's relatively small). It is continually (except at night) warmed by the sun. Energy once emitted by the surface returns to the surface and brings it to a temperature greater than solar energy alone would produce. Keep in mind that downwelling radiation has been measured from the surface directly for about twenty years. It's real. The atmosphere is radiating toward the surface. -
devon at 07:31 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
Could anyone give a real life example of cold heating hot, or energy being created from nothing as the K&T energy budgets suggest.
So, if cold could in fact heat the already hot, then this would have been established as a theory and a universal fact of physics. I would invite someone here to give a real life example! -
KR at 05:20 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
Energy can't flow from a cold source to a warmer object? But most of the world around me is cooler than my body temperature, and that means Aaaahhh, I'm blind!
Utter nonsense, Postma, utter nonsense.
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CBDunkerson at 05:04 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
Of course energy can't flow from a cold source to a warmer source... I mean, that's why when you open a freezer the light from the bulb in the back can't travel from the cold area at the back of the freezer to the warmer area of your eyes. :]
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Dikran Marsupial at 03:54 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
"It can be misinterpreted by inferring that a cold source can heat a warmer source. "
This essentially explains why JPostma wouldn't give a direct answer to my question, but it isn't the one he thinks it is. If some proposition X can be used to derive some conclusion Y, then if one accepts X then one must also accept Y, unless they can find an error in the chain of reasoning that links X to Y. However, the possibility that there may be a specious chain of reasoning that links X to Y is not a good reason to refuse to explicitly state that you accept X if you actually do. Refusal to do so is basically cowardice, not being confident that you will be able to demonstrate an error in the later chain of reasoning.
Unfortunately I suspect JPostma knows at some level that if he maes a genuine attempt to engage in the thought experiment, he might not be able to spot a flaw in the chain of reasoning, but is unwilling to accept that his understanding of Y might be incorrect.
This is why I often try to ask skeptics a series of carefully posed questions that are designed to define their position as clearly and unambiguously as possible, so that if they are right, we can all see if, and if they are wrong, then that will also be obvious. However in my experience, this is generally met by evasion. JPostma has provided a particularly clear example of this.
Moderator Response:[TD] I believe Robert Murphy has asked the next question that Dikran would have asked. JPostma, please give a simple yes or no answer to that question, and only then give any explanation that you'd like to give.
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John Hartz at 03:50 AM on 17 July 2014Rupert Murdoch doesn't understand climate change basics, and that's a problem
Also see:
Scientists Take Issue With Rupert Murdoch’s Remarks on Climate Change by Eric Roston, The Grid/Bloomberg News, July 16, 2014
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Robert Murphy at 03:47 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
Mr. Postma, when the photon from the cooler source hits the warmer source (which you acknowledge does happen), does the warmer source gain energy? Does the photon have any effect on the warmer body?
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Rob Honeycutt at 03:45 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
"It is unfortunate that so much time has to be wasted on BS like this."
Unfortunate, but also illuminating to watch cognitive dissonance on steroids.
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Dikran Marsupial at 03:42 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
"It can be misinterpreted by inferring that a cold source can heat a warmer source. "
O.K., give me an example of how that can be done.
BTW, the net flow of heat energy is always from the warmer object to the cooler, so it is pretty irrelevant anyway.
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JPostma at 03:39 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
"give me an example of how it could be misinterpreted"
It can be misinterpreted by inferring that a cold source can heat a warmer source. Of course, this is why the heat flow equation must be referenced with the answer, so that such misinferrence doesn't arise.
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KR at 03:39 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
Postma provides a great demonstration of denial here, in particular of the first law of thermodynamics, conservation of energy.
At equilibrium, which may include averaged short term variations around that equilbrium, the energy leaving a mass (surface, atmosphere, red-faced denier) equals the energy entering that mass (photons, convection, junk food). Input = output, in other words. If there is an imbalance, as with the current climate and radiative imbalance, internal energy will change and with it temperature.
The lowest radiative input to a mass, the lowest contribution to that masses temperature, would be the mass surrounded by absolute zero, with the 3K universal background radiation of deep space a close second.
Any object warmer than absolute zero, regardless of whether it is warmer or cooler than that mass, radiates photons according to its emissivity, and any of those photons absorbed by the mass in question increase it's energy. That added energy makes the mass warmer, until (via radiation, convection, conduction) the increased temperature causes the mass to lose energy at the same rate it gains it.
Radiation from anything above absolute zero will warm an object compared to its absence - and the warmer the radiating object the warmer the receiving object will become, no matter what their relative temperatures are. The starting point is zero, and even a relatively cool radiator provides a non-zero addition to nearby masses energies. Cool objects do, indeed, cause nearby warm objects to rise in temperature.
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Basic physics. Which Postma denies. His arguments are meaningless, Q.E.D. Not surprisingly, even many of the pseudo-skeptics disavow Postma and the 'Slayers', finding their imaginary physics an embarrassment...
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PhilippeChantreau at 03:37 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
It is unfortunate that so much time has to be wasted on BS like this.
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JPostma at 03:36 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
"give me an example of how it could be misinterpreted"
It will be misterpreted precisely by avoiding the heat flow equation, and thus thinking that perhaps the cooler object heats the warmer object because the cooler emission "hit" it. But of course, this is why it is important to reference the heat flow equation.
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JPostma at 03:34 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
More than avoid ambiguity, which is what would occur with a simple "yes or no" answer, I have provided the heat flow equation and some discussion of it to help clarify the fact that opposing emission is what determines equilibrium, and that the warmer object will not be heated, i.e., raise in temperature, due to the cooler object. I am sorry that I can not provide ambiguous answers, and that my explanation of the answer seems like ambiguity to you. But it is simple: cold does not heat hot, opposing emission determines equilibrium, etc.
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Dikran Marsupial at 03:31 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
JPostma writes "The problem is that answering only with a "yes or no" leaves the door open to misterpretation and sophist obfuscation of the physics"
Sorry, but that is hilarious. An answer of "yes" to the question "Does A emit any photons that strike B, "yes" or "no"?" leaves the door open to misunterpretation? Give me a break! Better still, give me an example of how it could be misinterpreted!
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JPostma at 03:29 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
"So, Mr Postma, for the last time, in the thought experiment described above, does object A emit any photon that strikes object B? Anything else than yes or no will be considered obfuscation by me."
The problem is that answering only with a "yes or no" leaves the door open to misterpretation and sophist obfuscation of the physics, because without the heat flow equation the meaning of the answer can be interpreted arbitrarily. Thus, I include the heat flow equation to help make it clear what the result of the physics is: heat not flowing from cold to hot, which means the warmer source does not increase in temperature.
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PhilippeChantreau at 03:26 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
I see the answer cam while I was writing my post. That yes has numerous consequences, which essentially negate your argument. "Following it up with Physics" is a fancy name for obfuscation. The condescending tone is rather amusing. I'm done here, that yes was all I needed to measure the depth of Mr Postma's need to receive Physics education, not give it
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Dikran Marsupial at 03:25 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
JPostma, I had repeatedly asked you just to reply "yes" or "no" to avoid all ambiguity, you chose not to, even when doing so would be a tacit admission that you were being deliberately obstructive. I am always happy to discuss science, and be proven wrong if that is what I am, however I don't have endless enthusiasm for obfuscation, and I don't think it unreasonable for people to give a direct "yes" or "no" answer when explicitly asked for it.
You have missed your chance to clearly explain your position. My thought experiment was designed to very clearly distinguish between two possible explanations of your position, but you chose not to co-operate.
Being willing to give direct answers to direct questions should be taken for granted in a scientific discussion, where the aim is to determine the truth. The fact that you needed input from the moderator should tell you that your behaviour was unproductive. Note the moderator did not delete your post, just gave advice.
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JPostma at 03:25 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
Q = sigma*(Th^4 - Tc^4) shows quite precisely that emission from a cold source does not heat up a warmer source. The emission from the cold source is what balances with the emission from the warm source in order to determine equilibrium - the emissions cancel out, leaving equilibrium, whether or not we wish to discuss whether the photons from the cold source "strike" the hot source...there is a greater physics occuring than that, as found in the heat equation, which shows how emission actually balances or cancels out at equilbrium.
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PhilippeChantreau at 03:22 AM on 17 July 2014Joseph E. Postma and the Greenhouse Effect
This is clear indeed, and rather boring. This is just a repeat of G&T nonsense and playing on words to spread confusion. We've talked at length about this years ago. Net heat transfer is different from energy transfer. Energy, under the form of photons, can be transferred from any object to any other object, regardless of temperature, as long as it is above absolute zero. Net heat, which in Thermodynamics is usually referred to as just "heat" can only go from hot to cold.
Postma's condescending tone does not match his unability to answer the very simple question posed by Dikran. Thers is no need to give additional information or "drown the fish" in a sea of words. The thought experiment described by Dikran is simple. The question is does A emit photons that strike B, not does A heat B or does A emit photons. The answer from Postma should be yes or no.
So, Mr Postma, for the last time, in the thought experiment described above, does object A emit any photon that strikes object B? Anything else than yes or no will be considered obfuscation by me.
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