Guest post by Reed Coray
The following example illustrates the issues I have with reasoning often used to argue that increasing the amount of CO2 in the Earth’s atmosphere will increase both the Earth’s surface temperature and the Earth’s atmosphere temperature. Immediately following is a direct quote from URL
http://www.school-for-champions.com/science/heat_transfer_earth.htm
“The present situation is that there has been an increase in infrared-absorbing gases in the atmosphere, such as carbon dioxide (CO2) and methane (CH4). Energy that would normally escape into space is absorbed by these molecules, thus heating the atmosphere and spreading through convection currents. The average temperature of the atmosphere has increased 0.25 °C since 1980, mainly attributed to an increase in infrared-absorbing gases in the atmosphere.”
Although the above statement makes no direct reference to Earth surface temperature, I believe it carries the implication that greenhouse gases in the Earth’s atmosphere increase the Earth’s surface temperature.
I make two comments: the first is relevant only if the above implication is valid, the second is relevant independent of the validity of the implication. First, placing matter adjacent to a warm surface such that the matter is capable of absorbing/blocking radiation to space from the warm surface can lead to a decrease in the warm surface’s temperature. Second, increasing the amount of the absorbing/blocking matter can lower the temperature of the absorbing/blocking material.
Take for example an internal combustion engine whose metal surface is exposed to a vacuum. In addition to doing useful work, the engine produces thermal energy (heat). That thermal energy will produce a rise in the temperature of the engine’s surface such that in energy-rate equilibrium the rate energy is radiated to space from the engine’s surface is equal to the rate thermal energy is generated within the engine. By attaching radiating plates to the engine’s surface, some of the energy radiated to space from the engine’s original surface will be absorbed/blocked by the plates; but because thermal energy can be transferred from the engine to the plates via both radiation and conduction, the temperature of the engine’s original surface will be lowered. This is the principle of an air-cooled engine[1]: provide a means other than radiation of transferring heat from an engine to a large surface area from which heat can be removed via a combination of conduction, convection and radiation, and the engine’s surface temperature will be lowered.
If plates at a temperature lower than the original engine surface temperature are attached to the engine, it’s true that the temperature of the plates will increase to establish energy-rate equilibrium. Once energy-rate equilibrium is established, however, increasing the plate radiating area (adding additional matter that blocks more of the energy radiated from the original engine surface) will likely lower the plate temperature.
Thus, blocking the amount of surface radiation escaping to space does not necessarily increase the surface temperature; and increasing the amount of radiation blocking material does not necessarily increase the temperature of that material. In both cases (the Earth/Earth-atmosphere and the internal combustion engine in a vacuum), the heat eventually escapes to space–otherwise the temperature of the Earth’s surface and the engine would continue to rise indefinitely. The difference isn’t that the energy doesn’t eventually escape to space (it does in both cases), the difference is in the path the energy takes to reach space. The amount of generated thermal energy in conjunction with the path the thermal energy takes to get to space determines temperatures along the path; and adding more material may increase or decrease those temperatures. To say that “Energy that would normally escape into space is absorbed by these molecules, thus heating the atmosphere…” by itself is unwarranted; because an equivalent statement for the case of adding extra plate material to the engine would be “Energy that would normally escape to space from an engine with small attached plates is absorbed by additional plate material, thus heating the plates…” For air-cooled engines, this statement is not true—otherwise the plate surface area of air-cooled engines would be as small as possible.
It’s fairly easy to visualize why (a) adding thermally radiating plates to an air-cooled engine might decrease the engine’s surface temperature, and (b) increasing the area of the radiating plates might decrease the plate temperature. It’s not so easy to visualize, and may not be true, why (a) adding greenhouse gases to the Earth’s atmosphere decreases the Earth’s surface temperature; and (b) increasing the amount of atmospheric greenhouse gases lowers the temperature of the Earth’s atmosphere. I now present one possible argument. I do not claim that the argument is valid for greenhouse gases in the Earth’s atmosphere, but I do claim that the argument might be valid, and can only be refuted by an analysis more detailed than simply claiming “Energy that would normally escape into space is absorbed by these molecules, thus heating the atmosphere.”
If we assume that (a) matter cannot leave the Earth/Earth-atmosphere system, and (b) non-greenhouse gases radiate negligible energy to space, then for a non-greenhouse gas atmosphere the only way thermal energy can leave the Earth/Earth-atmosphere system to space is via radiation from the surface of the Earth. The rate radiation leaves the surface is in part a function of both the area and temperature of the surface. For a greenhouse gas atmosphere, energy can leave the Earth/Earth-atmosphere system to space both via radiation from the Earth’s surface and radiation from greenhouse gases in the atmosphere. Suppose it is true that the density of greenhouse gases near the Earth’s surface is such that radiation emitted from low-altitude greenhouse gases does not directly escape to space, but is in part directed towards the Earth’s surface and in part absorbed by other atmospheric greenhouse gases. As the atmospheric greenhouse gas density decreases with increasing altitude, radiation emitted from high-altitude greenhouse gases can directly escape to space.
Now it’s not impossible that since (a) in addition to radiation, heat is transferred from the Earth’s surface to greenhouse gases via conduction, and (b) convection currents (i) circulate the heated greenhouse gases to higher altitudes where energy transfer to space can take place and (ii) return cooler greenhouse gases to the Earth’s surface, that the process of heat transfer away from the Earth’s surface via greenhouse gases is more efficient than simple radiation from the Earth’s surface. Many engines are cooled using this concept. Specifically, a coolant is brought into contact with a heated surface which raises the coolant’s temperature via conduction and radiation, and the coolant is moved to a location where thermal energy transfer away from the coolant to a heat sink is more efficient than direct thermal energy transfer from the heated surface to the heat sink.
One way to realize increased thermal transfer efficiency would be to use a coolant, such as greenhouse gases, that efficiently radiates energy in the IR band (i.e., radiates energy at temperatures around 500 K). Another way would be to spread the heated coolant over a large surface area. Since surface area increases with increasing altitude, thereby providing expanded “area” (in the case of a gas, expanded volume) from which radiation to space can occur, it’s not clear to me (one way or the other) that greenhouse gases won’t act as a “coolant” reducing both the temperatures of the Earth’s atmosphere and the Earth surface.
[1] It’s true that for most air-cooled engines the main transfer of heat from the engine plates is via a combination of (a) conduction of heat to the air near the plates, and (b) convection that replaces the warm air near the plates with cooler air. To aid this process, a fan is often employed, or the engine is located on a moving vehicle and the vehicle’s motion through an atmosphere provides the flow of air across the plates. Although conduction/convection may be the primary means of heat dissipation from the plates, radiative cooling also dissipates heat.
rgbatduke says:
July 22, 2012 at 4:22 pm
I’ve suggested two or three real falsifiable scientific experiments that you can do …But you don’t want to actually perform such an experiment,
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This is very funny, because I just wrote in my previous comment: “it looks rather typical for warmists: when asked for experimental proofs of their claims, they either say it is not necessary because it is so in theory or suggest the opponents do the experiment. Or they give “explanations” of what they have yet to prove. Unbelievable.”
Than you for the confirmation.
So far, I’ve increased my understanding from some of the replies in this thread (however incrementally). So it certainly isn’t “embarrassing” to me in any way, and I’d wager most others, too. Jeesh….
I’ll also add that Anthony is a professional weather scientist in his own right, and author of a book (which I proudly own) that will teach you to predict the weather, within reason, from a knowledge (that he provides) of atmospheric dynamics and physics. Very cool.
Without wishing to speak for him, I believe that he has indicated on countless threads that neither he nor most of the professional scientists who participate in these discussions “deny” that there is a greenhouse effect, that there has been global warming on average (not monotonic) since roughly 1850, or that human emissions of CO_2 may not have contributed some fraction of that warming. Very few scientists (climate or otherwise) or weather professionals would argue with any of this because there is direct evidence that he can read just as well as you or I for the greenhouse effect being “real”, direct thermometric evidence for the warming, and a very plausible argument that humans have contributed some of the increase in atmospheric CO_2 observed over time (although just how much is still the subject of some discussion, since very different — but all physically motivated — models are capable of explaining the increase with very different human inputs) and that this increase can plausibly be responsible for some fraction of the observed warming. I certainly don’t.
On the other hand, that does not automatically mean that I agree that most of the warming from any multidecadal interval in the record is due to CO_2 (and there has only been roughly 1.5 C of warming total across all 150 years with an increase in CO_2 concentration of around 1 decibel). If 100% of that warming were due to the CO_2, it would suggest that we could get a maximum of 3 more degrees C from the next two decibels (to a doubling). If 1 C were due to the CO_2 it would suggest 2 more degrees. If (most reasonably) 0.4-0.6 C were due to CO_2 it would suggest at most around 1 more degree. I think a lot of skeptics would agree that we could observe around 1 C more of total CO_2 induced warming by the time we reach 600 ppm, which IMO is likely to be at or very close to peak CO_2 before it starts to go down because people simply aren’t burning fossil fuels much any more not because of impending catastrophe but because they are too expensive and dangerous to mine and use and suffer from strictly increasing scarcity and risk of recovery (making them fairly predictably more expensive).
David Hoffer has an even smaller estimate, but not even the majority of climate scientists are calling for even 3 C any more (let alone the more egregious of the high-side estimates of Hansen’s papers past). AR5 will pick 2.8C as the median rise predicted by their collective GCMs IIRC, but there are plenty of climate scientists now that think it will be less, and the general trend is very much to lower the prediction. Who knows, skeptics and mainstream climate scientists might even converge in a year or five on 1.5 C or the like — non-catastrophic.
But Anthony does not censor even bad science out of the blog, and only rarely makes direct comments about bad science that shows up. In that I think he is wise. For one thing, to do so he’d have to make personal judgements about what is and isn’t bad science, and it is better to permit some really, really bad science in than to reject some good science by accident or ignorance. The debates usually reveal what is clearly bad, what is clearly good, and what might go either way, what isn’t really known or is up for discussion.
It is also, as you note, very educational even for non-participants in these discussions to hear the issues hammered out. You too have to form your own judgments as to what is and what isn’t a valid argument, who is and who isn’t well enough educated in the basic science involved to be at least approximately trustworthy, but you are better off doing so without Anthony’s peremptory intervention. Two of the other climate blogs that I can think of offhand engage in direct censorship and intervention, and both of them are seriously the worse for it.
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Don Monfort says:
July 22, 2012 at 4:46 pm
So Dr, Spencer is a warmist too.
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This is a purely technical term. Technically it looks like he is, yes, but certainly not a radical one. By the way, being a warmist does not automatically mean being wrong. If they scientifically prove what they claim I will certainly become a warmist, too.
I would appreciate it to no end if Greg House would post links to experiments that prove:
1. The earth is round.
2. That the earth orbits the sun.
TIA
Don Monfort says:
July 22, 2012 at 4:46 pm
Get yourself two radiant heaters from Costco. Turn one on high and the other on low. Stand between them. They both warm you. Right Greg? Remove yourself from between the heaters. Now they are warming each other.
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Can you prove that “now they are warming each other”? Proving it is necessary, just rephrasing the same claim alone does not constitute a scientific proof.
No problem if you can not, until now no warmist has been able to prove it, so you are not alone. The more important aspect is that they can not prove their key assertion. Looks bad for warmism. Scientifically bad, I mean, the propaganda machine is still working.
rgbatduke says:
July 22, 2012 at 4:57 pm
…there is a greenhouse effect, that there has been global warming on average (not monotonic) since roughly 1850, or that human emissions of CO_2 may not have contributed some fraction of that warming. Very few scientists (climate or otherwise) or weather professionals would argue with any of this…
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This is so not true. Even a well known study on “consensus” in fact proves the opposite: http://wattsupwiththat.com/2012/04/30/consensus-argument-proves-climate-science-is-political/#comment-972119 .
The concept of equilibrium between the surface and atmosphere above the surface is also nonsense. GHGes which compose an avg of 0.2% of the atmosphere have no discernable impact on temperature..if anything the effect is negative given the enhancing of the water cycle/general convection.
Well, er, or one could look at the top of atmosphere spectrographs. I would think a quantum physicist could read them, Phil. I’d think they could do a mental integral of the flux of the Poynting vector implicit in the data. I think they’d conclude that GHGs have a discernable impact on temperature. They damn sure have a discernible impact, at a concentration of 0.03% for CO_2 alone, on the TOA power spectrum, one that fits damn near perfectly (as real data goes) with blackbody curves. It’s also wise to look at simultaneous spectrographs taken from TOA looking down and bottom of atmosphere looking up. That way you can see where a measurable fraction of the missing energy goes — right back down to the surface.
With that said, I agree that one need to account for rotation, the heat capacity (especially of the 70% of the Earth that is ocean) and a lot of other things, but bear in mind that none of these things mean that CO_2 isn’t an important factor, especially the initial concentration that is not yet saturated. Right now CO_2 is saturated (the atmosphere is optically thick) so that the effect of varying the concentration of CO_2 is rather open to debate and yes, it may be that the full nonlinear coupling between CO_2 derived variations of temperature and water derived variations of temperature may turn out to cancel as easily as add, but that kind of question is what science is for. Evidence and argument first, conclusion later. It’s better that way.
Also, I wouldn’t assume that all of the GCMs ignore things like rotation, heat capacity, and so on. Rather the contrary. I don’t actually think that any of them are deliberately leaving physics out, even though they may be getting physics wrong (or being mistaken when they neglect something they think is negligible).
I just think it is a hard problem. I also think that we are decades short of having enough reliable data pulled from modern instrumentation that is even approximately global in its coverage. Anthony has discovered rather huge problems with straight up thermometric sampling, even with modern digital electronically recording thermometers. And this is, or should be, our most reliable data out of the entire 150+ year thermometric record. Which speaks sadly for the certainty or reliability of any gross conclusion drawn from the data.
UAH lower troposphere I trust, at least to be what it is, and fairly consistent. I’d even allow that it can be extended a decade or so with soundings. Surface and oceanic temperatures — the latter especially — are dubious even in the present, and doubly so in the past, although the ocean we may finally be sampling reliably if not sufficiently densely. Who knows, by 2030 or 2050, we might understand some things!
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Is that like a “last and final” boarding call at the airport? Redundant much?
Sorry, this thread needed a detour.
You have more patience than I would under the circumstances. Much appreciated.
Thirty years of teaching physics from intro through graduate level stuff, twenty five of that spent as an active theorist and computational physicist. And I have kids. Yes, I do get tired of trying to get Greg House to look at TOA/BOA spectrographs and try to predict them without using the physics of the GHE, and I very quickly got tired of SkyDragon’s inability to look at the pictures at the very top of this very article and note that the Sun emits the vast bulk of the energy the Earth absorbs in or near the visible part of the spectrum, at the very least at wavelengths clearly resolvable from those the Earth emits as it cools, but SkyDragon clearly does not understand (cannot derive) the blackbody radiation curves in the first place any more than Greg can. I can. I have — all physics students have to, usually while they are undergrad majors, as it is where quantum theory was really discovered. SkyDragon thinks that “heat radiation” is all in the IR part of the spectrum. So do a number of other posters. Apparently they never actually look up at the Sun, or look at an incandescent light bulb, or look at hot glowing coals, or…
I have no idea what Greg thinks about anything, since his entire argument seems to be “you can’t make me accept (some unstated proposition that varies from time to time) as proven. Prove the GHE with falsifiable data, he says. Look at the TOA/BOA spectra, I say — falsifiable data galore. No, he says, prove it. Prove that cold CO_2 can warm the ground. I proceed to offer proof after proof, including proofs he can prove at home. No, he wants a double blind, placebo controlled experiment that the actual atmosphere is warming the ground — back to the TOA/BOA spectra. But that’s not a proof, he wants… well, it’s not entirely clear what he wants, and since he has no hypothesis of his own to offer, falsifiable or not, the conversation gets rather circular. At that point I usually give up, but damn, on the next thread I try again. Some people never learn.
I’m talking about me, of course. I should learn not to get drawn in to hopeless cases.
The smart thing to do would be to pretend that he doesn’t exist at all. After all, maybe he doesn’t? Could he provide me with falsifiable experimental evidence of his own existence? That would be funny. He could send me a photograph, and I could say “but this isn’t really evidence of your existence, any more than TOA spectrographs are evidence of the GHE’s existence”. He could try to point to places where he’s had some effect — such as annoying me by pretending that my replies to his requests haven’t occurred, or aren’t “really” evidence — and say that if I really doubt it I could come visit him. I could then say aHA, so you can’t actually provide evidence (that doesn’t involve me doing something like looking). Then he could try again with a photograph, or birth certificate, and we could have a jolly old time.
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As a physicist you should know that far too little solar energy/area hits the surface of the earth for it to be broadly useful – even if conversion was 100% efficient.
Are you shittin’ me? As Samuel Johnson once said:
http://en.wikipedia.org/wiki/File:Solar_land_area.png
“Thus I refute you.”
The problem isn’t that there is far too little solar energy — hundreds of watts per square meter is plenty. The problems are (in order) cost per watt for the cells themselves, storage, and transportation. Of these cost per watt of the cells is paramount — if it is less than $1/watt and one can dump surplus energy back into the grid, the grid effectively stores and transports it, at least locally, and it becomes break even to win a bit to cover your very own house with a solar collector, at least in the US Southwest and much of the South. Other parts of the world it is even simpler as it is even sunnier — Australia, North Africa, Mexico, India, Arabia, all have plenty of sunlight, lots of silicon, and vast empty/desert spaces that nobody would miss if they were covered with solar cells.
But it is pretty simple to do the math. At $1.75/watt, $1750 buys a kilowatt. A kilowatt hour costs between $0.06 and $0.15 in different parts of the US. A rooftop collector can produce roughly 7 or 8 kWh a day — call it $1’s worth of electricity in high rent states, maybe $0.50 in the cheapest states. It takes 3 to 6 years to recover your investment — or would, except that you also have to buy an inverter for several thousand dollars and at least some buffering battery capacity even if you will automagically sell your daytime surplus back into the grid to help subsidize your nighttime consumption. Last time I looked it cost a bit over $11000 to buy 5 kW of rooftop capacity, installed — call it $2.25/watt. I live in a cheap-electricity state, which kicks the number of years to positive ROI on an amortized investment up to maybe 13 to 15, just barely not worth it on a twenty year basis, as $11,000 invested conventionally is probably worth about as much.
Drop the cost of cells alone to $1/watt, and the cost installed drops to $1.50/watt, including labor and inverter and battery. The $11000 drops to maybe $8000 for 5 kW, and I recover my investment even in NC in less than a decade. I then proceed to double it over the next decade. Assuming a 20 year lifetime for the cells and inverter — probably underestimates for both — it is at least as good an investment as anything I could do with my money that is relatively low risk. Even allowing something for maintenance and/or replacing the battery, the gamble of probably getting 30 years, over 20 of them actually making me money every year makes it a good bet, every bit as good as my replacement of my last heater/AC with a high efficiency unit that has halved my energy bills (but will take at least a decade or more to pay for its additional cost nevertheless).
Normal humans can do this math. It does not depend on government subsidy, although with the subsidy I could probably win a bit already even at current cell costs.
Corporate conversion is already at $1/watt per at commercially scaled prices. Power companies have a slightly different cost profile — they have to pay for land and labor where my rooftop is “free” to me — but they also realize a number of economies of scale, and in expensive-power states solar is already an attractive investment with or without subsidy. In all states roughly south of the Mason-Dixon line, dropping the consumer cost to $1/watt and the scaled cost to power companies to $0.50 to $0.75/watt would almost certainly suffice to start a major round of investment in solar conversion both on private rooftops and in corporate farms, not because it is good for the environment, but because it is a good investment. Other economies of scale would have some impact as well, as would other technological advances. Batteries, for example. Cheap enough battery capacity to allow solar to actually replace, rather than augment, conventional power would have a profound effect on the profitability.
As for fission, I just love fission, given sufficient care to avoid its known problems. The problem is that there isn’t enough Uranium/Thorium to last 10,000 years, although Uranium eked out by solar probably could easily last this long or even another 10,000 years. Definitely not a million years, or 50,000 years, though. The Earth is just too damn old, losing Uranium all the time. Still, I totally agree — if the powers that be, including the environmentalists, truly are worried about CO_2 and don’t want to destroy civilization (which is what pulling the plug on fossil fuels would do) in order to “save” it, they could put their money where their mouth is and provide every possible incentive to build nukes, ideally Thorium nukes where are much more bomb-proliferation-proof than Uranium nukes and (in at least some of the designs I’ve seen) nearly meltdown-proof as well.
Still, in the long run — and as noted I mean the truly long run, the steady state human civilization long run — the only fossil fuel that can stay the course is Deuterium. Deuterium is practically inexhaustible. Helium 3 would also be groovy but there isn’t enough of it; tritium too short-lived and dangerous. Without fusion, in 50,000 years the human race will be down to solar, wind, hydroelectric, geothermal — all of those currently despised technologies (although why they attract so much rancor is beyond me — burning stuff for energy is an expensive, dirty, pain in the ass even if CO_2 is so wholesome that we should all be concentrating it and sniffing it as a vitamin — speaking of which I like to whiff my own vitamins of this sort using a decoction of naturally fermented barley, water, and hops, pressurized by yeast in the bottle, and I do indeed have a bottle of very cold homebrew in my fridge that is calling to me, so I’ll cut this short).
This probably won’t be civilization ending, but it will make living in the northern temperate zone difficult, especially given that we’ll almost certainly be in an major glaciation period by then. After all, the Ordovician-Silurian ice age happened in spite of CO_2 at 4000 ppm, ten times what it is today, in the middle of its glaciation (it started when CO_2 was more like 7000 ppm) and nobody has convinced me that the same thing that started that ice age isn’t responsible for the current one, and that it has nothing whatsoever to do with CO_2. Indeed it might be nice to save some of the coal and oil for this era — but we won’t do that. Or rather, we probably will, because burning stuff for energy is an expensive, dirty pain in the ass, whether it is firewood in your fireplace or charcoal in your grill or gasoline in your gas tank or — ok, I’ll make an exception for methane through propane.
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David asks
So my questions are as follows. How much of the non GHG energy is radiated to space via collision with GHG molecues?
Essentially all of the IR radiated to space from the atmosphere is a result of collisional excitation of vibrational modes.
If the GHG molecues were not present, how much longer would this energy stay within the atmosphere if it could only be conducted and convected about, but not radiated to space.
The atmosphere would be much colder because the surface would be colder (somewhat technical argument related to the derivation of the adiabatic lapse rate starting with an average surface temperature). If you allow no ghgs, there would be no water vapor or clouds.
You can get an idea from this figure. Everything below the 320 K line is a result of ghgs re-radiating after collisions.
You raise the interesting question of what the energy of such an atmosphere would be. The temperature at each level would be given by the dry adiabatic lapse rate, the energy per unit volume given by CvT. where Cv is the effective specific heat.
<i.And, as additional GHG molecues speed the escape of conducted Non GHG energy, would not this reduced residence time of conducted non GHG energy have to be subtracted from the increased residence time of IR energy raqdiating from the surface, and backradiating from the GHG molecues? TSI incoming is a consistent flow, so the energy gained or lost by either radiating conducted non ghg energy out, or keeping surface energy within the atmosphere is porportional to the residence time of the energies affected.
This is somewhat backwards. GHGs (and increases in same) SLOW the escape of IR energy from the Earth surface and atmosphere together. Without GHGs the escape of IR energy from the surface is much faster, and if you look at energy balance, the speed up exactly matches the deficit from wiping out the ghgs.
Greg House says:
July 22, 2012 at 5:14 pm
Don Monfort says:
July 22, 2012 at 4:46 pm
Get yourself two radiant heaters from Costco. Turn one on high and the other on low. Stand between them. They both warm you. Right Greg? Remove yourself from between the heaters. Now they are warming each other.
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Can you prove that “now they are warming each other”?
Yes, measure the temperature of each when a) they are directly facing each other and b) when they are facing away from each other. Next.
Don Monfort says: referring to Greg
July 22, 2012 at 8:49 am
Does this clown think that the warmer body is transparent to the radiation from the colder body? Does it pass through without any effect? Or it detours around the warmer body? Bounces off?
Yes, Greg House is a believer in intelligent photon theory
Police Guy says:
The other day I put together a visual of 393 ppm CO2. This number reduces quite nicely to 4 parts per ten thousand. So I bought a plastic bottle with 10,000 bright yellow airsoft BB’s and removed its cardboard central piece to reveal an unobstructed view of all 10,000 BB’s to the viewing world. I then added 4 bright blue airsoft BB’s of the same size.
Add a drop of ink to a liter of water. Better, add 0.4 gm of a strong dye to a liter.
The bunny says: “Greg House is a believer in intelligent photon theory.”
And bun-bun is a believer in intelligent molecule theory: that sneaky CO2 is making the Arctic melt, and leaving the Antarctic alone.
Yes there is a “large raft of scientist” out there who know ever so much about radiation, but can you get one of them to explain to me, and other “disbelievers”, how it is that radio-waves can penetrate a brick wall while IR and other “light-radiation” stays on the outside? – I don’t think so. – Consensus, consensus, con——.
Any physicist — no, any physics major, by their third year, can easily explain this. You too could understand it if you tried, assuming you are moderately competent in calculus through partial differential equations and complex variables and are willing to take a year or two to learn it.
So, are you willing to try?
I’ll even take the time, on list, to reduce the explanation as much as I can to simple things that you can understand without necessarily using calculus, but it is really not that difficult. Some materials are transparent, some are opaque, because of their quantum molecular structure, in some frequencies but not others. Good conductors e.g. metals are usually not only opaque, but typically strongly exclude electromagnetic fields and hence reflect incoming E&M radiation — but still not necessarily in all frequencies. Insulators are much more variable. Brick, microscopically, is a good insulator and hence has a large skin depth for low frequency radiation, but the small sand particles are made of molecules that can absorb and reradiate optical frequencies quite well. Glass, on the other hand, often has a large skin depth in optical frequencies and only slowly attenuates visible radiation. Water is an amazing substance in and of itself — transparent almost precisely in the visible band, but rather opaque all around it, and with a transparency and reflectivity that varies with its state and structure. Sea water is moderately transparent to visible light, but as a good conductor blocks/reflects many frequencies but, curiously enough, not very long wavelength radio waves.
But the main things you’ll need to learn to get a first order understanding of this are skin depth (explained/derived in my online book on Electrodynamics) as a generic response of charged matter to incident radiation, subject to dispersion, and quantum mechanics, which explains the details of the dispersion and predicts the actual interaction between electromagnetic radiation and atoms or molecules of various kinds.
If, on the other hand, you aren’t really interested in trying and are just trying to assert that physicists have no idea why brick walls let radio waves through but not visible light or IR, then as previously noted, you need to stop wasting everybody’s time. The only person’s time you should be spending is your own, studying. You remember studying? It involved getting out textbooks, finding mentors, taking classes, and working your ass off, the same as everyone else who ever learned the material. No shortcuts, no you’re not so intelligent that you can do it without hard work by means of your own sheer brilliance and intellect, and yes every single step along the way is individually confirmable in laboratory experiments.
You stand on the backs of giants, sir, whether or not you wish to acknowledge them, and you couldn’t even type out your responses on this blog on your computer and have them be transmitted over an electronic network and be transformed in due time into light and dark patches on your screen if physicists and engineers could not only answer your questions, but answer them in detail. The evidence is literally at your fingertips as you read this. Do you really want to pretend that this isn’t the case, that we really don’t know how to make electrons sit up and dance?
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Beng says:
Why does the altitude that radiation escapes get higher?
Because absorption is proportional to the number density of the absorbing molecules. When the number density is high enough, essentially direct radiation to space is blocked, the emission from the ghg molecule lower down gets absorbed higher up and does not escape to space.
I very patently asked them to present a link to a real scientific experiment proving that notion, but they failed (http://wattsupwiththat.com/2012/06/22/a-response-to-dr-paul-bains-use-of-denier-in-scientific-literature/). Does not look well for the concept.
And I provided him with a link to a real scientific experiment that produced real spectrographs that proved that notion. His response then, as now, is to pretend that this never happened, or that it doesn’t prove the notion, it isn’t clear which. But don’t take my word for it — follow the links and compare TOA and BOA spectrographs taken at the same location and time, and observe the complimentary greenhouse hole at the top and backscattered radiation in the exact same greenhouse bands at the bottom. If direct measurements of the radiation isn’t evidence, then — to Mr. House — nothing will be, as he isn’t really interested in the evidence, he’s interested in repeating a claim over and over again in spite of the evidence.
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paulinuk says:
July 21, 2012 at 9:01 pm
I’ve another simple question for Joel Shore etc : If ”non- radiative” gasses such as N2 and O2, H2 can’t radiate thermal energy in the IR that they have acquired through conduction then a jet of N2 or O2 at 15c emitted by a spacecraft in a vacuum wouldn’t show up on an IR thermal camera would it (but a jet of C02 at 15c would)? The simple experiment’s been done, hasn’t it?
Couldn’t we then use O2,N2,H2 to store vast amounts of energy so long as they were in deep space and as you say they “can’t radiate” much? Just imagine, we could heat up H2 to a million degrees and hardly no heat would radiate from it.
Clever enough :), but the sun is a plasma, not a gas and in any case you would need some gravity to hold the damn thing together.
Again, I thank everyone for responding to this guest post.
Those who claim this post is embarrassing may be right. But if so, it’s primarily an embarrassment to me and maybe secondarily to Anthony. I can’t speak for Anthony, but I can stand whatever embarrassment you ascribe to this post.
I infer from some of the comments on this thread that some people believe (a) that greenhouse gases have a negligible effect on the rate the Earth/Earth-atmosphere absorbs solar energy, and (b)atmospheric greenhouse gases “slow down” outgoing radiation, and it is this “slow down” that warms both the Earth’s surface and atmosphere. In an earlier comment (July 21, 2012 at 5:15 am) I asked the question “Under what conditions does the presence of greenhouse gases in the Earth’s atmosphere quit slowing-down outgoing radiation?” As far as I can tell I never got an answer to that question. So to those who believe/claim (a) and (b) above, I repeat the question. If the answer is: “As long as there are greenhouse gases in the atmosphere, they never stop ‘slowing down’ outgoing radiation”, then I’d appreciate an answer to the obvious follow-up question: “If (a) the presence of greenhouse gases in the Earth’s atmosphere doesn’t change the rate radiation (energy) is absorbed by the Earth/Earth-atmosphere system, (b) in the absence of greenhouse gases the energy-rate equilibrium temperature is T, and (c) greenhouse gases always ‘slow down’ outgoing radiation which causes the temperature to rise, then why doesn’t the temperature increase without bound (or at least until the greenhouse gases go away or the temperature changes so that the temperature is high enough that radiation from the Earth/Earth-atmosphere is negligible in the greenhouse gas absorption bands)?”
Eli Rabett says:
July 22, 2012 at 7:05 pm
Can you prove that “now they are warming each other”?
Yes, …
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Yes you can! Yes you can! Yes, this is hilarious…
“Can you prove it?” in that context means “Prove it!”, you know, it was not a real question, the question form is rhetorical. And “Prove it!” does not imply your telling me to prove it. You guys should prove your claims, not we.
Now I am looking forward to a link to the scientific falsifiable experiment proving that. What, you have nothing? I thought so.
davidmhoffer says:
July 22, 2012 at 11:44 am
Michael Tremblay;
Create any experiment which will take advantage of GHG’s to create an engine which will run on radiative energy alone.
>>>>>>>>>>>>
Given the number of times in this thread alone that it has been specified that the physics being explained is reliant upon an external energy source, one can only wonder if people like you even bother to read the explanation.
>>>>>>>>>>>>>>
That comment was totally uncalled for.
I have read most of the explanations and I know that they are talking about an external energy source.
You seem to hold a misconception that all engines are run by an internal energy source. This is simply not true – I have sitting on my desk a small working model of a Stirling Heat Engine. It is run by using an external energy source.
My suggestion was that someone could get out of their scientific ivory tower working with theoretical physics and apply them to a practical purpose by making a physical model to quantify the effect.
Add a drop of ink to a liter of water. Better, add 0.4 gm of a strong dye to a liter.
Damn you sir! I wish I’d thought of that. But David’s original answer wasn’t bad either. And food coloring is even readily available!
I wish I could find good IR photographs in the CO_2 band. They should illustrate image attenuation quite dramatically. Do you know of any? I’d think they might convince — no, wait, who am I fooling.
I’m tired, though, and have just written another 10k words or so. Time to drink heavily (that one whole beer I mentioned above, my contribution to the GHE for the day) and either work on a real book or go to bed. Or play poker with my sons. I suppose I could play poker.
rgb
rgbatduke says:
July 22, 2012 at 7:22 pm If direct measurements of the radiation isn’t evidence,
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Of course it is not. You need to prove you key assertion that radiation from a colder body can warm a warmerbody. Radiation is very nice, but you guys apparently can not present any link to a real scientific experiment proving this alleged warming effect, not just radiation.
I hope now after I told you that like for the 999th time (just my feeling) you will understand the point.
No, I didn’t miss anything, but it’s becoming obvious that you missed mine.