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Now that the kiddies are back in school, I’m seeing greatly increased traffic at my Weather Questions website. The most visited page is almost always the one explaining the greenhouse effect. (WARNING: comments posted in response to this article will undoubtedly include a few from people who claim the greenhouse effect is physically impossible, does not exist, etc. )
What amazes me are the number of science education web pages out there which claim to describe experiments that supposedly demonstrate the greenhouse effect using jars or other enclosures.
But these experiments can do no such thing.
There is no simple way to demonstrate the greenhouse effect of a small sample of air experimentally with a jar or any other enclosure because over the scale of inches to feet (or even tens of feet) the effect is so weak it cannot be measured with standard thermometers. (Our friend Anthony Watts tried to replicate one totally bogus experiment promoted by Al Gore and Bill Nye the Science Guy).
Now, the infrared absorption properties of small samples of greenhouse gases can indeed be measured with very expensive spectroscopic equipment in a laboratory, but there is no way I know of to do it with jars or other enclosures and a thermometer.
My favorite atmospheric greenhouse effect experiment that does actually work uses an inexpensive handheld infrared thermometer pointed at the sky. This is the most direct demonstration I know of. The reason it is a “direct demonstration” is that the IR thermometer measures tiny temperature changes within the handheld sensor resulting from changes in the amount of IR energy entering the sensor.
This is exactly what the greenhouse effect does to the surface temperature of the Earth: changes in downwelling IR radiation cause changes in surface temperature. It really is that simple.
(NOTE: Even though handheld IR thermometers are supposedly tuned to work at IR wavelengths where atmospheric greenhouse effects are weak, there is still a residual effect. Besides, even if IR thermometers could completely avoid greenhouse gas effects, they would still be sensitive to the greenhouse effect from clouds. Just point the IR thermometer at the clear sky, and then at a low cloud: the warmer IR thermometer reading from the cloud is due to the greenhouse effect from the cloud. Period. End of argument. QED.)
So, science teachers beware. Those greenhouse effect experiments are junk. Do not try them at home.
Dear Dr. Spencer:
There are more variables to consider in thermocouple experiments that you have used to prove the existence of the greenhouse gas effect. One variable is water vapor condensation when, as you described, a “very” humid air scenario is the case. Water vapor condensation can be infinitesimal, yet it releases a substantial amount of latent heat of condensation that can heat the thermocouple. A second variable is the impact of infrared radiations from buildings and land when the thermocouple direction is lowered to the horizon. In short your experiment is a very “crude” one and conclusions cannot be drawn from the experiment.
Sincerely,
Nabil Swedan
Nabil:
1) I describe in more detail in one of the links provided how one can perform such experiments.
2) Even if condensation were to occur, it would only reduce the effect — not cause a “false positive”
3) Yes, it is a crude demonstration. It demonstrates the existence of the greenhouse effect…not its magnitude.
Dear Dr. Spencer:
Many insects around the world utilize the physics of the thermocouple experiment to “drink” air moisture. The stay still on an angle with their mouths in the lowest point. As the temperature of their hard shell cools below the air dew point, water vapor condenses on their shells. The condensed water then rolls down by gravity to their mouths and they drink. This way they can survive years of drought.
The question that poses itself, if the greenhouse gas effect and back radiations exist then all surfaces warm steadily first then the surrounding air follows. Water vapor would never condense and the insect would have been long dead from thirst. But they are still around, which suggests that there must be another explanation of how surface temperature rises.
Back radiations, in the radiation energy equation between two surfaces, do not exist in practice; they are only for calculation purposes. Radiation travels from the hot surface to the cold surface. This is the law of nature. The same is true for Ohm’s law and Fick’s law. There is no back electrical current from the point having low voltage to that having higher voltage. There is only one current from the high voltage to the lower voltage. Back electrical current is only for calculations and has no physical existence. The same reasoning is valid for the Fick’s law.
Sincerely,
Nabil Swedan
With respect Roy, are you proving that the ‘greenhouse effect’ results in warming of the Earth’s surface temperature by measuring cloud? The net effect of which is cooling. Like in the lab the inability to measure the effects of CO2 thermally from the ground on a clear day with a device that can measure the back radiation from cloud is convenient. My IR thermometer regularly shows -44 to -46 Celsius from blue sky at zenith.
All the so called ‘greenhouse gases’ are active through the near infrared as well as in the long wave. William Herschel discovered infrared prismatically with a thermometer and in doing so proved that ‘heat’ is not light and that light is much less efficient at ‘warming’ matter than visible light. Please explain how interfering with thermal energy coming in and out automatically results in warming. It doesn’t work with cloud.
Also there is the subject of opacity and optical depth. If ‘greenhouse gases’ genuinely absorb rather than scatter why do we not measure an increase in temperature across the optical dept of absorption? Again it will be so small as to be unobservable no doubt. Plus if it absorbs it has to radiate and if optically thick and thermalised it has to reveal itself to an infrared thermometer. Plus if we think that all the other matter in the atmosphere is radiationally inert then the ‘only’ way the atmosphere can lose heat to space is through ‘active’ radiative components like ‘greenhouse gases’.
Correction, please read
In doing so proved that ‘heat’ is not light and that light is much less efficient at ‘heating’ matter than near infrared.
Nabil, I agree. When water vaporises it takes on heat and when it condenses that energy is released. That is well known to become the power of hurricanes and tornadoes when it overcomes the lapse rate. The energy of change of a downgrade of state results in local warming.
I have an IR imaging thermometer, so I’ll replicate your suggestion.
I would be most grateful if you did. The lowest reading you ever measure is the one with the least water condensation. That’s the only variable by scientific consensus. The lowest measurable is the one dominated by the powerful ‘greenhouse gases’.
I have played with such a thermometer for a year, and it is both funny and instructional. Unfortunately it stops below -20C and just shows “low”.
In august here in Denmark we had a week with very warm and moist weather. I heard the cause was situated in Sahara.
Anyway it was the only time i could get a measurement pointing at blue sky, -5 to -15C.
Normally i use the cloud temperature to estimate the hight of the cloudbase via the lapse rate.
An other observation is, that the lawn when a bit green keeps below 25C even in full sun, and concrete slaps get 40C+.
This observation made me think of GW and UHI.
One interpretation is that UHI of cause is part of the Global Temperature, but an eventual effect of CO2 must be judged by the rural temperature. Even if UHI is Man made.
There is actually a relatively simple demonstration of the classic non-convective ‘backradiation’ greenhouse effect, you can do it with a bucket of water.
Water is transparent to visible light, but very, very opaque to thermal IR. (You can check that with a thermal IR camera.) So the black bottom of a sunlit pool of water absorbs energy, re-radiates it, and that radiation is ‘trapped’ by the opaque ‘greenhouse liquid’.
In a normal bucket of water, no warming results, even though there is plenty of backradiation being emitted by the water (as your IR thermometer will show). This is because convection short-circuits the radiative resistance completely. (The convective greenhouse effect is lapse rate times average emission height, both of which are small in a bucket of water.) So to see the classic effect, we have to stop convection.
The ‘solar pond’ is a shallow pool of water with a strong vertical density gradient, created by varying the salinity. Dense salt water is put on the bottom, fresher water on top. It has to be done slowly, so the water will be perfectly still. Then even warm water at the bottom will still be denser than cooler water at the top, and convection is suppressed. (There are probably more efficient ways, but solar ponds actually exist.)
Then with radiation and convection blocked, only conduction is left to allow the heat to escape, and the temperature rises. Solar ponds out in the open can reach around 90 C at the bottom of a couple of metres. It’s an ideal ‘greenhouse’.
The *convective* greenhouse effect is very close to zero in a pond, though, despite the considerable backradiation that exists, and is a lot harder to exhibit in a laboratory. To demonstrate a convective greenhouse effect would require a super-dense, highly compressible, IR-absorbing, sunlight-transparent fluid, to achieve a perceptible lapse rate in a bucket. That’s a lot taller order, and I can’t think of an easy way. But perhaps it will help to correctly define the problem.
If you believe that the effects of adding a few metres of anything as a two dimensional interface with solar radiation can produce a measurable effect then you are correct. If you think you are altering the albido of your local weather environment or that of the planet then you may have to rethink by a few orders of magnitude. You do need a -50thermopile thermometer to measure blue sky.
Nullis in verba. Does that mean ‘nothing to say’ in Latin. Tho whole point of the atmosphere is that it is convective buddy. Convective to a point you obviously don’t appreciate. When opacity upsets it convection sets in. The whole atmosphere is gravitationally bound and gravity ‘dictates’ the energy distribution. Convection sets in when it doesn’t like what’s happening. The fact that your trying to explain the action and reaction of gases to a liquid shows the limits of your understanding. There is no thermal lapse rate in the sea or ocean. Eigenvalues?
Geoff,
I find it slightly disorientating when someone argues with me by agreeing with what I just said, as if I had said the opposite. It gives the strong impression that they’re not really reading what’s written. Or something.
You did get a couple of bits wrong. Gravity doesn’t ‘dictate’ the energy distribution. There is a thermal lapse rate in the ocean: it’s about 0.1 C/km. And no, it doesn’t meant ‘nothing to say’.
I didn’t follow what it was that “doesn’t like” something. Gravity? The energy distribution?
And “your trying to explain the action and reaction of gases to a liquid” seems to better show the ‘limits of your understanding’ of English grammar. That wasn’t what I was doing anyway.
And I have no idea why you added the word “Eigenvalues” to the end of your piece. Was it just some random word you picked, like ‘Calorescence’?
My full apologies in mis-reading your intentions Nullious in Verba. It is very unusual to find someone who agrees to the point that they will comment on anything constructively. I owe and acknowledge the necessary apology.
In the atmosphere the degrees of freedom are all equivalent and that leads to a rationalisation through equipartition that does not exist in a liquid. The energy states in a liquid separate the pressure energy from the thermal energy through differing eigenvalues that maintain separation. Gravitational energy in a sea or a deep ocean is invested in pressure which is energy density not thermal energy. That is why the deepest ocean is never warm. Thermal energy could be added there but would automatically lead to convection through expansion.
Notwithstanding that these experiments are designed to prove the existence of the ‘overall’ Greenhouse Effect, does anyone know of a non-modelled experiment which measures the contribution to the GE from CO2 (and other GHGs)? If so, can you provide a link please?
Arfur,
I don’t know of an experiment, but I think CO2 accounts for approximately 1/3rd of the absorption spectrum; however, when overlap with absorption from clouds that would occur anyway is considered, CO2 accounts for about 10% of the GHE.
Sorry, but I had thought we had educated you out of this faulty thinking. What you measure with a pyrometer pointing at the sky is purely the thermal IR.
The Aarhenius idea of the ‘GHG blanket’ is absurd because it depends on the assumption that the IR from the Earth’s surface is the same as an isolated black body in a vacuum. Any process engineer like me says that’s plain stoopid because convection and radiation are coupled: http://www.thermopedia.com/content/204/
The real GHE is from the reduction of surface emissivity by that thermal IR annihilating the IR from the surface, standard Poynting Theorem physics forgotten by too many and, so it seems, not taught nowadays in the pseudo-sciences.
The 23 W/m^2 [2009 energy budget] absorbed by the atmosphere is water vapour side-bands not in self absorption. All these facts are self-evident to a professional physicist.
Apologies: there will be 11.5 W/m^2 pseudo-scattered water sideband IR, a sort of mini ‘GHG blanket’. To claim 333 W/m^2, black body emission for 3.7 deg C, is ludicrous because it’s a radiometer artefact – the shielding means it detects the vector sum of the Poynting vectors in the viewing angle.
You prove this very simply – have two radiometers back to back in zero temperature gradient and the net signal is zero. Take one away and you measure the temperature signal.
This incredible mistake by meteorologists originally, now climate science, has led to the modelling being essentially nonsense, full of fudging, the same relationship to proper science as painting by numbers is to fine art. Sorry, but this failed science has to be put out of its misery!
Nullius in Verba says:
“Then with radiation and convection blocked, only conduction is left to allow the heat to escape, and the temperature rises. Solar ponds out in the open can reach around 90 C at the bottom of a couple of metres. It’s an ideal ‘greenhouse’.”
Not entirely convinced.
Solar radiation at equator in ‘perfect’ surface absorption conditions can reach theoretical 123C.
So 90C would perhaps sometimes represent cooling.
Test inside away from the Sun or at night.
Heat surface plate with thermostatically controlled and energy measured electrical supply.
Temperature of plate held constant at 90C
Test One with water above plate.
Strong IR absorption so maximum back radiation.
Test Two same procedure as test one but with;
Potassium Permanganate solution replacing water
Reduced IR absorption and smaller back radiation.
Compare the energy supplied to the plates in test one and two.
If ‘greenhouse theory’ is correct there should be significantly more energy supplied to plate in Test Two
dear dr. spencer,
respectfully, again, can you put a ‘print’ feature on you posts. i hear you on rush from time to time. patrick j. michaels of cato has his able to print. you two are the most accurate that i follow.
The point is that the presence of greenhouse gases in the atmosphere reduces the heat flow to space (which is what Roy Spencer showed in his box experiment).
If you reduce heat flow from a body which is gaining thermal energy at a constant rate (the surface from solar radiation), that body will heat.
Gerlich and Tscheusner had a great example of this, which is, as far as Eli can see, the simplest experiment which captures this key element of the greenhouse effect, put an empty pot on the stove and then put a pot with water on the stove. Turn the burner (electric or gas) on. What is the difference in temperature between the two pots.
Thermal blankets are another simple example. Restrict net heat flow from the surface, it warms.
Another point which is often lost in the half up half down argument is that migration of heat from the surface to space by radiation is effectively blocked by the short average path length of absorption in the atmosphere of the IR within the absorption band of the greenhouse gas molecules.
I don’t think anybody can argue about a theoretical greenhouse effect.
The real question though is what are all the effects of IR active gases in the atmosphere in total.
If the atmosphere were pure oxygen and nitrogen and IR inactive the atmosphere would be a lot warmer than it is.
The ground probably would not be but we don’t measure that.
As they say there is more than one way to cook a goose.
bill hunter: ‘I don’t think anybody can argue about a theoretical greenhouse effect’
Oh yes I can! There can be very little GHG-AGW by a ‘GHG blanket’ because GHG thermal emission from the atmosphere annihilates most of that band emission from the surface.
The physics is simple and is taught to all process engineers in decent engineering schools: e.g. MIT, Imperial, Cambridge.
The most basic axiom from Maxwell’s Equations is that the net IR energy flow at any point is the vector sum of the Poynting vectors arriving at that point in space.
Engineers calculate it as the difference between the theoretical S-B emission for the isolated bodies in radiative equilibrium.
Because IR surface IR emission is much reduced, the Aarhenius GHG blanket is not possible and anyone who believes in it betrays lack of basic physics’ knowledge.
The real GHE is mostly the rise in temperature needed to overcome reduced surface emissivity.
Climate science blundered into a blind alley by assuming the Earth emits IR as an isolated black body in a vacuum by abusing the ‘back radiation’ concept, an imaginary signal which only appears because of the shield behind the detector.
Adding it to net UP IR recreates the UP PV, most of which can do no work. The Schwarzchild approximation in Houghton’s treatise fails at boundaries because there the errors can’t cancel out.
In time, us engineering professionals expect a heartfelt apology from those in climate science and other disciplines who persist in their calamitous heat transfer and generation mistakes, born out of ignorance.
Sure you can argue, but you make absolutely no sense at all! Actually you are not arguing, you are ranting, because an argument needs two people.
As for your supposed science, I have never read such an unmitigated load of bollocks in my entire life. Infra red emissions “annihilating” each other?!? WTF?
There are big problems with the whole catastrophic AGW hypothesis, but the existence or otherwise of back-radiation at IR frequencies from CO2 in the atmosphere is not one of them. It exists and, although a small effect (compared to back radiation from water vapour in the atmosphere, which is mainly what Roy is seeing), it is measurable. Flat-Earthers like you are a laughing stock and bring the whole “true” sceptical argument into disrepute.
TLM: do you really think I wrote this without thinking out the issues? And have you passed these ideas to a competent physicist before pronouncing they are wrong?
I trained in process engineering long before computers took over thinking and worked in metallurgical plants, including developing the first non contact two-colour pyrometers for non grey body materials, so my experience is vast.
Climate science dismisses reality. So annoyed was I with this mulish behaviour, I set out to establish the real physics. It’s the Poynting vector argument.
At the Earth’s surface, at any wavelength, net radiative energy flux is the vector sum of all Poynting vectors, see the Wikipedia article. There is subtle additional physics but climate science’s ‘black body’ claim can’t be true.
Sorry, but this is heat transfer reality. Most heat transfer in the atmosphere is convective. You would have to heat a 0.85 emissivity solid to ~100 deg. C before IR radiation exceeds natural convection – and I have measured this.
PS: this Thermopedia article is a good primer for coupled convection and radiation: http://www.thermopedia.com/content/204/
If only climate science had looked at the process engineering literature, it wouldn’t have led us on an expensive wild goose chase and the humiliation of its predictions being overturned by empirical observation.
Step 1 to recovery will be to accept that the pyrgeometers measure the vector sum of the Poynting vectors in the view angle, not real energy flux.
There is no doubt that the greenhouse effect is real and there is no doubt that Al Gore’s experiment is a fatally flawed method of trying to demonstrate it. I think that the myth-busters did something similar. It is not clear what these experiments are seeking to prove. That CO2 has lower specific heat than air and so will warm up quicker? It has, so it should, but you could look that up in engineering tables. It proves nothing about radiative transfer because, as Anthony Watts points out, normal glass jars are opaque to infrared at 15 microns – so nullifying the whole point of the experiment which must be to show that CO2 is absorbing radiation at this frequency and so warming up faster.
However, trying to use a normal infrared thermometer to measure ‘back radiation’ seems equally inept. These devices are specifically designed to operate in the IR window, between 8 and 12 microns, and so not see atmospheric radiation. Trying to draw conclusions or ‘proofs’ from residual noise readings with an instrument that is known to be beyond its calibration limits is simply bad science. Furthermore, it is not necessary since professional measurements of downwelling radiation can and have been made with Fourier transform radiometers. These results are widely available on the internet and constitute all the proof you need of back radiation.
TLM: I agree fully with what you say but I fear you are wasting your breath.
Spartacusisfree, Poynting vectors and Maxwell’s equations relate to the behaviour of electromagnetic fields. This is a red herring argument, suitably complex in order to befuddle the reader. Nothing to do with infra-red radiation in the atmosphere at all.
I am afraid “trained in process engineering” does not cut it. When dealing with climate and weather I am more likely to believe somebody with a Ph.D. in meteorology thanks.
TLM: the average Poynting vector for a plane wave is epsilon0.c.E0^2/2 W/m^2 and is in the direction of propagation. The net IR radiative energy at the Earth’s surface is the vector sum of all IR PVs arriving at that point.
This is elementary physics derived from Maxwell’s Equations which apply to all electromagnetic phenomena, of which light is but one manifestation.
Meteorologists are taught incorrect physics: there is no ‘downwelling LW’ energy; it’s the vector sum of the PVs in the viewing angle of the detector and if from a lower temperature atmosphere can do no thermodynamic work because it is completely annihilated at the surface.
This is well known to the pyrgeometer manufacturers who specify you need two, back to back,to measure net radiative energy flux: http://www.kippzonen.com/?product/16132/CGR+3.aspx
This failure by Meteorology and Climate Science is probably the biggest scientific cock up in History, a fact not opinion. And my PhD is in Applied Physics.
MikeB: the spectrometric data showing the atmosphere emits thermal IR in GHG bands is real. However, because the measurement is of the vector sum of the Poynting Vectors in the viewing angle, it is no measurement of real energy flux.
If the atmosphere is at a lower temperature than the Earth’s surface, all that ‘downwelling energy’ is annihilated at the Earth’s surface by its IR emission, the net result being reduced surface emissivity in those bands.
This is self-evident to any competent physicist or engineer. The fact that it has been misinterpreted is not proof of incorrect physics. Ask any objective professional physicist to comment on this argument, and they will agree there has been an awfully big cock up.
As an aside, read up the reports by professional physicists on climate issues and they are full of caveats to distance the authors from the incorrect physics.
A good example is here, an official APS publication: http://www.aps.org/units/fps/newsletters/200807/hafemeister.cfm
In Eq 14 they analyse the lower atmosphere emissivity needed to make an energy balance with the Earth’s surface emissivity = 1. This is a fudge because there is no analytical solution because the Earth’s emissivity can also fall and there is an infinite set of solutions.
The reality is that the atmosphere model based on ‘back radiation’ doing work and DOWN TOA emissivity = 1 is false and has to be corrected.
Dear MikeB:
No one has ever modeled mathematically the greenhouse gas effect and back radiations, including the great Fourier. If it cannot be modeled mathematically, then it does not exist. A real effect can be measured, mathematically modeled, and experimentally replicated. None of these has been possible with the greenhouse gas effect because it is fiction.
Sincerely,
Nabil Swedan
Nabil: it takes someone who has measured real IR radiative energy transport, temperature radiation fields and simultaneous convection to do the job.
Back radiation can do no work. The real GHE is the rise in surface temperature to overcome reduced emissivity and convective heat transfer coefficient, so is also very difficult to model.
These issues have been completely ignored by academia for 30 years in favour of organised deception.
@Spartacus and Dr Spencer
Spartacus, am glad you understand your reference as I don’t find it a comfortable pre dinner read. In support of your conclusions I put forward a crude but simple experiment that anyone can try.
The 333 W/m2 back radiation has disturbed me for some time. So a quick crude test is to use the front (more sensitive) of the wrist to test for heat difference.
Test one: place the wrist to face the sky. Apply large polystyrene sheet (PS) over it say 30cm above and note the difference. Friends and I can never detect a difference with or without the PS barrier.
Test two: Same wrist but place a 60W incandescent globe so that the filament is 12 cm above the wrist (this gives a max 333 W/m2 to the wrist). Keep the polystyrene above at 30 cm.
The results are that invariably with blindfold, switching on and off , at various times during the day we can detect when the light is on or off (i.e thru the heat we feel).
The results are very clearly noticeably different from Test one and would suggest back radiation can’t be that high.
My location is Perth, Australia which is 32 deg south so quite moderate ambient temperatures in early Oct and represent a reasonable back-radiation average. Tests are done in the open in the shadow of a building (i.e. no direct sunlight).
Sure it is crude but it does lead me to the question has anyone conducted more controlled experiments to actually measure this back radiation average that is put forward in climatology – other than using prgeometers.
TonyM: I have tried the same, placing 3 ft x 3 ft aluminium foil on a lawn at night, no wind. Put you hand 6 inches above the foil; and you can’t feel any warmth on the back of your hand.
And my measure of 333 W/m^2 is 4 feet from my mother’s old Beeston kitchen boiler!
The Meteorologists have for 50 years misinterpreted pyrgeometer readings just because they are calibrated in W/m^2 and measure the Poynting vector as a proxy for temperature convolved with emissivity.
This is systematic failure to think properly through their experiments.
I would say the GHE is really one of radiative resistance to cooling and not so-called ‘back radiation’ (i.e. downward LW from the atmosphere to the surface). That is, the absorption of upwelling radiation from the Earth’s surface acting to cool that is absorbed and subsequently re-radiated back downward. To overcome this resistance to radiative cooling, the atmosphere and ultimately the surface are warmer than they would otherwise be in the absence of GHG absorption of surface radiation.
In the simplest of terms, on Earth at 288K it takes about 390 W/m^2 of surface radiative power to allow 240 W/m^2 of radiative power to leave at TOA. The difference of about 150 W/m^2 is that which has its ultimate origin in radiative resistance to cooling.
Convection is primarily just a process that accelerates radiative cooling by moving energy non-radiatively higher up in the atmosphere where when radiated it has a greater chance of passing through into space. Thus convection offsets energy that would otherwise have to be radiated from a warmer surface in order to achieve equilibrium with space.
RW: a 15 deg C Earth cannot emit IR as a black body because at that temperature, well less than half can be radiated, the rest leaving by convection [assumed to be natural]. Forced convection will leave much less to be radiated.
See this reference for the Thermopedia analysis of coupled convection and radiation: http://www.thermopedia.com/content/204/
Professional engineers have been using this maths for 50 years. Climate Science came in 30 years ago cl;aiming it knew better when all it was doing was fooling itself and the rest of the World. It’s time it was told to concentrate on real physics not the phantasy stuff it has convinced itself is reality.
“RW: a 15 deg C Earth cannot emit IR as a black body because at that temperature, well less than half can be radiated, the rest leaving by convection [assumed to be natural]. Forced convection will leave much less to be radiated.”
I’m not sure I understand what you’re objecting to. All convected power from the surface is in addition to that directly radiated from the surface.
At 288K, the 390 W/m^2 radiated from the surface includes the effects convection has on the energy balance. Of course, the surface is not truly black-body – just very close to one. Liquid water has an emissivity of like 0.99, so maybe about 386 W/m^2 radiated is closer to reality?
RW: convection and radiation are coupled so at equilibrium sum to the input energy. This is because the same sites transfer internal kinetic energy to adsorbed gas molecules or EM energy, and vice versa. There are 6 rate equations and emissivity and absorptivity, also the convective heat transfer coefficient are determined by statistics.
The reason why the temperature is higher than you’d expect for the combined energy emission is because the reduction of the number of those sites increases the impedance to heat emission, the real GHE.
You cannot use the S-B equation for a black body when there is also coupled convection. This is because the heat transfer coefficient is an empirical parameter with the de facto emissivity falling as convection increases.
I realise this is a hard concept to swallow for people whose sole teaching is to look at S-B in the textbook. However, heat transfer is far more complex than climate science imagines because the GHGs turn off surface emission sites.
I suspect I’m ploughing virgin turf here but someone has to be the pioneer and you can never create energy by magick!
Of course convection and radiation are coupled together. I don’t see how this refutes anything I’ve said. The surface radiates into the atmosphere about 390 W/m^2 because this is also the net flow of energy in at the surface that sustains the surface temperature of about 288K. Or are you disputing that temperature is slaved to power by the S-B law?
Also,
You seem to be describing how the atmosphere manifests the net flow of energy in at the surface, which of course is the net combined result of both radiative and non-radiative processes in the atmosphere. However, this does not describe the fundamental mechanism of the GHE, but rather describes and involves why the surface temperature and/or surface energy balance is what it is.
Maybe I should revise my statement to say:
“Effectively, on Earth at 288K it takes about 390 W/m^2 of surface radiative power to allow 240 W/m^2 of radiative power to leave at TOA. The difference of about 150 W/m^2 is that which has its ultimate origin in radiative resistance to cooling (i.e. surface emitted radiation upwelling acting to cool that is absorbed and subsequently re-radiated back downward).
“The reason why the temperature is higher than you’d expect for the combined energy emission is because the reduction of the number of those sites increases the impedance to heat emission, the real GHE.”
Is what you’re describing here (i.e. “impedance to heat emission”) NOT that of radiative resistance to cooling?
I believe considerably warmer nighttime temperatures with a cloudy sky compared to clear sky conditions prove IR down welling does increase temperature of the surface. at night you only have IR emission and to produce warmer nights some of that radiation is returning.
Hi Sparatcusisfree, good to see someone who understands & has experience with heat transfer make a comment. I have had experience with heat transfer. I have designed burners for different fuels (coal, gas, oil & waste materials) and made measurements in different furnaces to determine efficiency. I have been meaning to add a post on my blog about radiation heat transfer and the lack of understanding of the Stefan-Boltzmann equation which as you say in its original form only applies to black bodies in a vacuum. Engineers (chemical, process and some mechanical) often need to determine heat loss from equipment. Convection, natural or forced, is by far the most important at low temperatures (ie close to atmospheric) for heat loss eg a “radiator” grill on a car. It is shaped to have an high surface area. It does not radiate significantly but uses forced convection aided by a fan at low (or zero) speed of the car.
Climate scientists do not grasp the basics of heat transfer.
It seems none of them have read the work of Prof Hoyt Hottel (Prof. of chemical engineering at MIT and author of a book on radiative transfer, and co-author of the section on heat &mass transfer in Perry’s Chemical Engineering Handbook)
Reply to RW:
The energy heating the Earth’s surface is 160 W/m^2.
At equilibrium, the same leaves with 63 W/m^2 radiation and the rest convection and evapo-transpration.
The emissivity is 63/396 = 0.16.
To try and claim you get black body radiation in an atmosphere is plain wrong. It only occurs for an isolated body in a vacuum, and that body will have to be a cavity.
All real materials behave differently.
All I’m saying is at 288K with an emissivity near 1, the surface must be supplied with a net flow of energy in of about 390 W/m^2, which is also then the amount the surface radiates into the atmsosphere. I’m making no contention there isn’t a significant amount of non-radiative energy moved from the surface into the atmsophere via evapotranspiration and convection. There most certainly is.
The emissivity of the planet is about 0.62 (240/390 = 0.62). This means of the 390 W/m^2 radiated from the surface, only 240 W/m^2 is allowed to leave at the TOA.
“The energy heating the Earth’s surface is 160 W/m^2.”
The direct solar power that reaches the surface is about 160 W/m^2, but the total solar power entering the system is about 240 W/m^2, yet the surface is supplied with 390 W/m^2. The post albedo energy from the Sun is the only significant source of energy entering the system, so really the full 240 W/m^2 is acting to ultimately heat the Earth’s surface, albeit not all directly as SW radiation.
cementafriend: I knew Hottell. I agree that the climate scientists should read Perry’s!
I have also made car radiators by vacuum brazing, now superseded by gluing.
RW: “390 W/m^2 radiated from the surface”. Is this true? Seems to me that lower tropospheric temperature is a measure of the kinetic energy of all the gases in the atmosphere at a particular altitude, principally O2 and N2, and is not entirely reliant on radiation from the surface, although surface heating contributes by radiation and convection.
Am I wrong?
Spartacus/AlecM: I would also value your comments. Thanks.
This does not demonstrate the greenhouse effect in any way. For example if you point the device at anything that reflects back infra-red radiation such as a reflector from afar it will also give a false positive for this theory. The reason being extra thermal energy is being reflected back into the sensor. Exactly like shining mirrored light into someones face causing more energy to be focused in one place. This is amplification of energy, which is like saying a transistor operates because there is a greenhouse effect!
Do we even know if the Stefan-Boltzmann Law even applies to this debate. What makes anyone think Trenberth et al Energy Budget is right. These are all numbers averaged and estimated; nothing is beyond question in science. The earth is in a vacuum, space, however because of our atmosphere and its surface, it is not a black body. The maximum temperature of the earth would be hotter not colder without an atmosphere. From this I conclude the atmosphere acts to filter the Suns energy and keep the earth cooler during the day than it would otherwise be. The surface of the moon is 123oC so what do you think our temperature would be without an atmosphere.
Increasing the molecules that are opaque to SW/LW radiation will probably alter how the atmosphere responds however whether this will increase or decrease the temperature is still unknown. Nothing is proven.
The Greenhouse theory relies on molecules that are opaque to radiation and as these molecules exist in our atmosphere it seems logical that some radiation is sent back down to the surface however, where does 333w/m2 come from; someones vivid imagination. As far as I know, Perpetual motion machines of any kind are still impossible. The notion that the energy entering the system is increased by Greenhouse gases is impossible but if I’m wrong, the energy crisis is over. Trenberth obviously doesn’t know how radiation works and what entropy is.
Dr Roy is right about these ridiculous attempts to reproduce the GH effect in a jar but what is really worrying is that many people see these experiments e.g. Mythbusters and believe it. I read this statement somewhere and I’ve always liked it ‘the earth is an open chaotic system of unpredictability’. Science is about finding the answers but some commonsense would come in handy.
Askwhyisitso: Common sense is not too common in the climate science. If there were backradiations of greenhouse gases, infrared astronomy would not have existed and it would be a waste of time and money. Infrared radiations from the universe, that are captured by infrared telescopes, are merely a tiny fraction of the alleged backradiations. In an infrared world, the backradiations will certainly overshadow the infrared signals coming from the universe-It is like trying to see Jupiter at noon looking straight up in the direction of the Sun, which is impossible. Either the infrared astronomy is false or the back radiations of greenhouse gases are false, they cannot coexist at the same time.
>>>”…changes in downwelling IR radiation cause changes in surface temperature. It really is that simple”.
Have you confirmed that, Roy, or is that another one of your thought experiments?
Down-dwelling IR from GHGs that represent 1% of atmospheric gases raises several concerns:
1)it would require removing 99 panes of glass from a 100 pane greenhouse to model the atmosphere.
2)since the GHGs are theoretically warmed from a warmer surface, which is warmed by solar energy, the back-radiation would have to add to solar energy and all losses from the surface would have to be ignored.
Since the GHG heating came from the surface, a lick of common sense tells us that same heat cannot be recycled and added to solar energy. The heat acquired in GHGs came at a loss of IR at the surface, and coupled with the tremendous losses that bypass GHGs, there is no way to make up that lost energy via the positive feedback you suggest.
The maddening thing for me is that you argue against that positive feedback in models yet you are defending it here.
in other words:
3)the 2nd law of thermodynamics forbids HEAT being transferred from a cooler atmosphere to a warmer surface THAT WARMED IT. Clausius made it clear that IR can be transferred between surfaces of differing temperatures but that HEAT can only be transferred from hot to cold, under ordinary means.
Roy
I am confused.
Does not the following experiment demonstrate the heat absorption property of CO2?
http://www.youtube.com/watch?v=Ge0jhYDcazY
Girma
Girma: Temperature rise is too high in the experiments. I suspect that the heat of reaction has to do with it. Carbon dioxide absorbs the light more than some gases. But it does not trap radiations as suggested in the climate models. There is no practical evidence of radiation trapping of any gas.
Roy, you said: “The reason it is a “direct demonstration” is that the IR thermometer measures tiny temperature changes within the handheld sensor resulting from changes in the amount of IR energy entering the sensor.”
Now, remembering the alleged “greenhouse warming”, where the small part of IR radiation from -18C cold surface sent back by the “greenhouse gases” should produce a 33C warming, my question: why do you call the alleged temperature changes on the sensor TINY?
The sensor must get really very very hot, because it gets almost all the IR, not just a small part of it. I guess a few hundreds degrees C sensor warming is possible, right? You must be very careful with those measurements in order to not get your hand burned.
Or maybe you have some reasonable doubts now?
Roy, I am not an expert on IR thermometers, but is it possible that the sensor just detects IR radiation from the remote object and then the temperature of the remote object is calculated by means of measuring the changes in the electrical current the radiation causes in the sensor? That’s probably why you can not do it with a usual thermometer.
And the sensor is not just anything, but is made out of special material, although there are a lot of things that absorb IR radiation and can get warmer.
On the other hand, causing changes in the electrical current is not equal to making warmer, isn’t it?
Still sure IR thermometers prove the “greenhouse effect”?
@Greg
for your information IR thermometers use a thermopile which is an array of thermocouples.
http://en.wikipedia.org/wiki/Thermopile
They measure the difference of temperature on the two sides of the sensor. So pointing such radiometer to a colder surface and measuring its temperature doesn’t prove that the colder body is heating the sensor. In fact the temperature sensor embedded into that thermometers is used to establish at which temperature the thermopile produces 0 Volts. Above and under that temperature of the sensor the thermopile produces different polarity because the side exposed to the input slit is heated or cooled respect to the other side, depending on the temperature of the target.
Massimo, you are surely familiar with the 33C “greenhose effect” narrative.
So, if it is -18C outside and the sensor is -18C cold and you point it to the sky, it must get +15C because of the back radiation of the “greenhose gases”, right?
Now, you turn the thermometer and point it to the ground thus getting the whole ground radiation, not just a small portion of “back radiation”. The sensor must get really hot now! As I said, the difference must be huge, if the “greenhose effect” narrative is correct.
Does it happen in reality?
Hi Greg,
I don’t agree with Dr.Spencer’s theory about the IR thermometers which should prove that there is any back radiation.
Anyways I think that it’s not so simple as you suppose. In fact the IR thermometers are “proxy instruments”. That is, they measure the temperature by heating/cooling one side of their inner sensor via the incoming/outgoing IR net radiation which passes through their input slit.
They are just calibrated to show the temperature correlated to the specific IR net flux at their very own temperature of the moment and nothing more.
As I already told some month ago in this blog, in my opinion no way the temperature reported from the IR thermometers pointed to the sky is representative of the average temperature of the atmosphere. It’s just the result of the net flux of the IR energy which passes through the input slit.
Note that I write “net flux” and not incoming or outgoing flux.
That is, I can’t tell you if there is any flux from the colder sky which enter the slit and heat the sensor indeed, but at the same time I can’t deny its existence.
I’m still waiting for a physics proof of the GHG theory, which should never come from any statistical homogenization or any other arbitrary adjustment.
By the way, I’m not a scientist, I’m just an engineer and the above are just my own modest opinions.
Massimo PORZIO says: “By the way, I’m not a scientist, I’m just an engineer and the above are just my own modest opinions.”
=============================================
To me, it absolutely does not matter who you are. Besides, the term “climate scientist” is highly discredited, since many of them engage in speculations selling it as science.
Massimo PORZIO says:
“Anyways I think that it’s not so simple as you suppose. In fact the IR thermometers are “proxy instruments”. That is, they measure the temperature by heating/cooling one side of their inner sensor via the incoming/outgoing IR net radiation which passes through their input slit.”
===============================================
The question is whether the radiation of a colder body produces changes in the sensor’s temperature or just changes in electrical current without changing temperature. Another question would be, even if there were some changes in the sensor’s temperature, did the radiation from a colder body produced it or something else?
At least all the possibilities should be scientifically explored. This is unfortunately not what Dr.Spenser has been doing. In other words, what he has presented does not prove his assertion, that’s the point.
And, of course, the apparent contradictions of the “greenhouse effect” concept (as presented by the IPCC) to the reality I pointed out to in my previous postings still remain.
Greg:
“The question is whether the radiation of a colder body produces changes in the sensor’s temperature”.
I answer yes, because the sensor is a thermopile and that kind of sensor works that way, but I can’t tell you whether it does it because the incoming IR flux really heat that side of the sensor or just because it reduces it’s capability of dissipate its own heat trough the input slit.
” or just changes in electrical current without changing temperature.”
No I’ve no doubt on that, a thermopile needs a temperature difference between its two sides to generate a voltage, the link at Wikipedia that I posted before explain it clearly.
“Another question would be, even if there were some changes in the sensor’s temperature, did the radiation from a colder body produced it or something else?”
The problem for me is: did anybody out of here ever demonstrate that an IR flux at a lower frequency than those emitted by the solid on which the same radiation impinges enter the solid or limit in some manner the solid heat radiation?
One day I did an experiment with a light bulb having two filament and I believed to having measured the cold to hot energy tranfer, but looking at the IR spectrum of the two filaments in that setup, I discovered later that their two black-bodies-like emissions where highly superimposed. That is, there was some IR energy from the colder filament which was at higher frequency than some IR energy which was emitted from the hotter one.
I still miss that proof.
Massimo PORZIO says:
“Greg:
“The question is whether the radiation of a colder body produces changes in the sensor’s temperature”.
I answer yes, because the sensor is a thermopile and that kind of sensor works that way,”
=================================================
OK, assuming that and that the sensor must be reasonably made out of a very sensible to IR material (and apart from that they amplify the incoming IR), let us come back to my example:
“So, if it is -18C outside and the sensor is -18C cold and you point it to the sky, it must get +15C because of the back radiation of the “greenhose gases”, right? Now, you turn the thermometer and point it to the ground thus getting the whole ground radiation, not just a small portion of “back radiation”. The sensor must get really hot now! As I said, the difference must be huge, if the “greenhose effect” narrative is correct. Does it happen in reality?”
Does not look realistic to me. Apparently it does not go both ways, so something wrong must be with the “greenhouse effect”. The first guess would be: if it exists, it must be extremely weak. This can explain, why no warmist have come up with a real scientific experiment proving the alleged “33C greenhouse warming” or just like 7C warming from CO2 alone. No experiment, Ladies and Gentlemen.
On the other hand, the experiment by professor Wood from 1909 is well known. Even very much (compared to CO2) back radiation from glass did not produce any significant difference in temperature. The hypothesis died successfully and warmists from those times accepted it.
Dr.Spenser, why not admit the obvious?
Massimo PORZIO says “Note that I write “net flux” and not incoming or outgoing flux.That is, I can’t tell you if there is any flux from the colder sky which enter the slit and heat the sensor indeed, but at the same time I can’t deny its existence.”
———————————————————–
Masimo,Your analysis is correct. Infrared astronomy tells us that there are no backradiations from the atmosphere. In fact there can be no radiations of any sort between the atmosphere and the surface because the two masses are in intimate contact. Only conduction and convection heat transfer is expected from two masses in contact with each other.
Hi Greg,
you wrote:
— So, if it is -18C outside and the sensor is -18C cold and you point it to the sky, it must get +15C because of
the back radiation of the “greenhouse gases”, right? Now, you turn the thermometer and point it to the ground thus getting the whole ground radiation, not just a small portion of “back radiation”. The sensor must get really hot now! As I said, the difference must be huge, if the “greenhouse effect” narrative is correct. Does it happen in reality?—
I’m not sure I got your point (I’m Italian and maybe I misunderstood what you wrote).
If you are talking about the energy density (spatial density, due to the very tiny CO2 concentration and even spectral
density, due to the CO2 very thin absorption pit at about 15um) I agree with you that the green house should be a
negligible effect.
Note that the spectral issue should be better investigated, because I read the “AGW crew” at RealClimate asserting that the 3W/m2 reduction flux at TOA for the CO2 doubling is an incontrovertible “fact”. If that assumption is true then it doesn’t matter how the density is distributed along the spectrum, but in my opinion they missed that the instruments they use to measure (or better to simulate, indeed) doesn’t measure the whole outgoing radiation, but only the one exiting the TOA into a narrow angle around the nadir. There is an Italian research, done few years ago with a spectrometer on a balloon in Brazil, which in a figure shows that there is a lot of outgoing flux which must be taken in account for angles outside the ones seen by the satellites. Note that the energy is exactly outgoing only at the very same wavelength of the CO2 absorption (at the tested 34km average altitude).
You wrote again:
— …The sensor must get really hot now! As I said, the difference must be huge, if the “greenhouse effect” narrative is correct. Does it happen in reality?” —
No it doesn’t, but we can tell nothing about the existence or not of the back radiation with that. That’s because the very same way as do the satellites, the IR thermometer uses a very little energy flux to infer the temperature of its target. Just for example: when you want to evaluate the efficiency of a 100W lamp bulb it’s not necessary that you put all its power on the optical power meter sensor to measure it. Typically the lamp bulb is placed into an integrating sphere to make the flux homogeneous on the outgoing slit of the sphere and after having calibrated the sphere to a know reference light source, very few mW are enough to infer the bulb power.
The same way, the IR thermometer sensor may change its temperature of very little fractions of °C to range hundreds of °C at its input.
About the Wood experiment I read that Nasif S. Nahle (a Mexican researcher) repeated that experiment last year using polyethylene sheets instead of the mineral salt of the “no IR greenhouse” box and got the very same results you refer to.
See the link below:
http://www.biocab.org/Experiment_on_Greenhouses__Effect.pdf
As you can see there, he checked other kind of IR shields too and it was meticulous in his experiment.
I believe that that’s the way science is meant to be, not the silly Youtube BBC plastic bottle experiment I seen linked before.
Have a nice day.
Massimo
@Nabil Swedan,
I partially agree with your “Only conduction and convection heat transfer is expected from two masses in contact with each other.”
That is I believe that radiation should have a minor impact on everyday temperature, but the Pictet’s experiment clearly shows us that radiation exist even in the atmosphere.
www2.ups.edu/faculty/jcevans/Pictet’s%20experiment.pdf
About the IR astronomy, I believed that it was done at the so called “near infrared” and “middle infrared” bands, that is with wavelengths comprised from 750 to 1500nm and 1500 to 5600nm, not in the “far infrared” band which the “long wave” thermal IR is present.
I admit that I don’t know much about that.
Have a nice day.
Massimo
Massimo PORZIO says: “About the Wood experiment I read that Nasif S. Nahle (a Mexican researcher) repeated that experiment last year using polyethylene sheets instead of the mineral salt of the “no IR greenhouse” box and got the very same results you refer to.
See the link below:
http://www.biocab.org/Experiment_on_Greenhouses__Effect.pdf
As you can see there, he checked other kind of IR shields too and it was meticulous in his experiment.”
===================================================
Thanks for the link, Massimo. I knew about it, but I prefer to reference to the Wood’s experiment also because of the date: 1909. PRIOR to the first IPCC report, Kioto protocol and even the James Hansen’s birthday.
But I am afraid Dr.Spencer likes his IR Thermometer much more than the Wood’s boxes. It must be so much more fun to just point that wonderful device to the sky and voilà!
Massimo PORZIO says: “Greg:
“The question is whether the radiation of a colder body produces changes in the sensor’s temperature”.
I answer yes, because the sensor is a thermopile and that kind of sensor works that way,”
=================================================
Well, I think there is still another possibility.
The fact is, that IR from the object produces some electrical changes in the detector and these changes are measured, not the ones in detector’s temperature.
It is possible that while IR from a warmer object causes changes in detector’s both temperature and voltage, IR from a colder object causes changes only in voltage and not in temperature. And since IR from a colder object causes changes in detector’s voltage, the temperature of the object can be calculated.
For practical purposes of remote temperature measurements it is not important, what exactly happens with the detector, it works and this is wonderful. But those who claim there are changes in detector’s temperature should prove it.
Of course, it is not primarily about IR detectors, so generally, to prove that a warmer body’s temperature is affected by IR from colder bodies an experiment is necessary. Maybe in vacuum, in order to exclude conduction and convection.
If there is none, the key assertion of the modern warmism remains unproven and is not essentially different from a fiction.
Hi Greg,
—If there is none, the key assertion of the modern warmism remains unproven and is not essentially different from a fiction.—
I absolutely agree with you about that. That’s what the real science is meant to be.
About the fact that —It is possible that while IR from a warmer object causes changes in detector’s both temperature and voltage, IR from a colder object causes changes only in voltage and not in temperature.—
No, this is proven wrong. The Pictet’s experiment that I linked before in a former post addressed to Nabil Swedan, demonstrates that a colder body reduces the warmer one by radiation because the point where the warmer body is more cooled by the setup of the experiment is exactly in the focus of the parabolic reflector. That clearly demonstrates that radiation works the two ways by radiation.
Have a nice day.
Massimo
Hoops! In the message that I sent before I wrote — That clearly demonstrates that radiation works the two ways by radiation.—
Please read: — That clearly demonstrates that heat transfer works the two ways by radiation.—
Dear Massimo PORZIO:
I looked at the Pictet’s experiment, and the experiment does not qualify to conclude that cold can be radiated to warmer objects, absolutely not. Had this really what happened in the experiment, then the mass of ice located at focus C would increase as a result of “cold radiations.” We know that this did not happen and the mass of ice melted instead. The thermometer at focus D was located at a point of heat sink and it lost heat by radiation to the cold iced water and that is why its temperature decreased and that is why the ice melts.
Furthermore, if cold can really be radiated, it would have a lot of practical and useful applications. Show me one! On the other hand, there are a lot of heat radiation applications on the market.
Nabil
@Nanil Swedan.
No, I never meant that. If I lead you to think that, I apologize for that.
What Pictet showed there, is that a warmer body if placed nearby a colder body can reduce the heat which escapes from the warmer body, that compared to the warmer body alone in an environment colder than the colder body itself.
IMO that’s what happen in the IR thermometer when aimed to the sky.
Cold can never “radiate” of course.
Have a nice day.
Massimo
Massimo PORZIO says: “What Pictet showed there, is that a warmer body if placed nearby a colder body can reduce the heat which escapes from the warmer body,”
================================================
Thanks for the link, Massimo.
I am sorry to possibly disappoint you, but no, the Pictet’s experiment does not show that. It only shows that if a colder body actually works like a shield when put in a warmer environment thus, decreasing radiation the thermometer receives from that warm environment, which causes a decrease in the thermometer’s temperature.
You can do the same with an IR heating device by putting something between you and the device. Then you will feel less warm immediately.
Funny that the initial interpretation of the Pictet’s experiment was like “discovery of a cold emanations” or “radiation inducing cold”. I can the same way “discover” dark emanations by putting something opaque between a light bulb and my eyes.
Pictet’s experiment does not demonstrate at all that IR radiation of a colder body reduces cooling of a warmer body.
Hence the main assertion of warmists’ remains unproven.
P.S. This is the essential quote from the description of the Pictet’s experiment:
“Two metallic mirrors A and B, each 15 in. in diameter, with focal lengths of 15 in., were placed opposite one another at a distance of 16 ft (see Fig. 1). A sensitive air thermometer was placed at the focus D of one mirror. When a cold object (in this case, a glass bulb ?lled with water and pounded ice) was placed at the other focus C, the thermometer at D began immediately to descend.”
Hi Greg.
yes, you are right, I wrote my reply to Nabil without reading what I wrote.
The right statement was:
“What Pictet showed there, is that a colder body if placed nearby a warmer body can reduce the heat which escapes from the warmer body, that compared to the warmer body alone in an environment colder than the colder body itself.”
I apologize, I did a little confusion, but when I wrote that post I was leaving the office to return home and I did it too hurriedly, I just swapped the first occurrence of “warmer” and “colder” 🙂
You wrote:
—You can do the same with an IR heating device by putting something between you and the device. Then you will feel less warm immediately.—
No is not the very same case of the Pictet’s experiment, since in that case you don’t know if you receive less or more heat by radiation or convection/conduction. The Pictet’s experiment showed the presence of radiation because the distance between the two body, where they exchanged more heat was not the shorter but exactly the distance between the focuses of the parabolic reflectors.
So it demonstrates that even in an atmospheric environment there is radiation not only convection or conduction.
(Note that I’m not arguing what really Pictet believed to have discovered, it doesn’t matter to this context).
Returning to your assertion that the IR sensor into the thermometer could generate voltage without changes at its temperature on the side exposed to the input slit: it’s wrong, because it is exactly the same as Pictet’s experiment showed, only that instead of the parabolic reflector the IR thermometer has a polyethylene Fresnel lens as focusing device.
Just to explain how it works, make that Tenv is the temperature of the environment, Tt the temperature of the target at which the IR thermometer is aimed. Make that the IR thermometer is stabilized at the very same temperature of the environment Tenv.
Case 1) Tenv<Tt :
the exposed side of the sensor inside the IR thermometer is heated by the target so the delta temperature produced at the opposite sides of the sensor is (just for instance)+10mV, then the internal signal conditioner computes the temperature adding the equivalent temperature for +10mV to the inner temperature sensor which reads Tenv. So the result showed by the thermometer is Tenv+T10mV, that is Tt.
Case 2) Tenv<Tt :
the exposed side of the sensor inside the IR thermometer is cooled by increased radiation of the sensor on the side exposed to the target so the delta temperature produced at the opposite sides of the sensor is (again just for instance)-10mV (the exposed side has cooled because the lens seen a cooler target instead of the warmer environment), then the signal conditioner computes the temperature subtracting the equivalent temperature for -10mV to the inner temperature sensor which reads again Tenv, so the result showed by the thermometer is Tenv-T10mV, that is again Tt.
The only case in which the temperature of the exposed side of the thermopile sensor is not changed is when Tenv=Tt in that case the thermometer shows only the temperature reported by the inner sensor because the thermopile is a perfect shortcircuit (0V.
That doesn't means that aiming the sky with the IR thermometer one can demonstrate the presence of any back radiation, on that I always agreed with you from the beginning. Because there is no evidence that any radiation come into the IR thermometer, it just cools its sensor exposed side lesser than if it was aimed to the outer space directly.
You were just wrong claiming that — IR from a colder object causes changes only in voltage and not in temperature— No that's proven wrong by Pictet's experiment, the temperature on the exposed side is cooled in that case.
Have a nice day.
Massimo
Massimo PORZIO says:”I apologize, I did a little confusion, but when I wrote that post I was leaving the office to return home and I did it too hurriedly, … 🙂 …The Pictet’s experiment showed the presence of radiation because the distance between the two body, where they exchanged more heat was not the shorter but exactly the distance between the focuses of the parabolic reflectors.
So it demonstrates that even in an atmospheric environment there is radiation not only convection or conduction.”
=================================================
I guess you were in a hurry again… (sorry, I could not resist that :))
Let us remember what the cardinal issue is: whether IR radiation of a colder body reduces cooling of a warmer body. It is not just about “presence of radiation”. Radiation is present indeed in this is wonderful.
Has the Pictet’s experiment proved that IR radiation of a colder body reduces cooling of a warmer body? No.
A colder body in this experiment was just an obstacle for IR from the warm environment and therefore the temperature of the thermometer decreased (shield, remember?), that is all. You can not squeeze more from it.
Massimo PORZIO says: “Returning to your assertion that the IR sensor into the thermometer could generate voltage without changes at its temperature on the side exposed to the input slit: it’s wrong, because it is exactly the same as Pictet’s experiment showed, … Case 1) Tenv<Tt …Case 2) Tenv<Tt :
the exposed side of the sensor inside the IR thermometer is cooled by increased radiation of the sensor on the side exposed to the target…"
===============================================
No problem, I understand what you mean :).
Well, again, the Pictet’s experiment has not shown that IR radiation of a colder body changes temperature of a warmer body.
To the sensor, yes, it works, because as a result of changes in the received IR there are some electrical changes, and they are measured.
But this alone does not prove that there are also changes in temperature the IR receiving part of the sensor, if the targets are colder than the IR receiving part of the sensor.
@Greg,
—Well, again, the Pictet’s experiment has not shown that IR radiation of a colder body changes temperature of a warmer body.—
Uhmm… I suspect this have became just a wording problem. That is, ok if you consider the absolute radiation it CAN’T cool the warmer body of course, but if consider the net flux compared to the one which interested the warmer body when it was alone, it’s clear that the (reduced) radiation of the colder body is the cause of the increased net radiation of the warmer one. I always refer to net fluxes not the absolute fluxes coming from the bodies. I believe that I’ve been clear that I don’t agree with the Pictet’s belief in cooling radiation. In my opinion Pictet just removed any doubt about other thermodynamic heat exchanges involved in the setup because the simple fact that the maximum exchange of heat happens in the focus of the parabolic reflectors excludes convection and conduction. That’s for me is the great of Pictet’s experiment.
Returning to the your —But this alone does not prove that there are also changes in temperature the IR receiving part of the sensor, if the targets are colder than the IR receiving part of the sensor.— I don’t know how to tell you in other words, but you are wrong here because when the input slit is aimed to a target colder than the IR thermometer itself the exposed face of the sensor MUST be cooled by the (reduced) radiation outgoing net flux of the input slit.
Being the thermopile an array of thermocouples in series having one metal on one side (say iron) and an another on the other side of its body (say constantan = copper-nickel alloy), the only way you have to make it producing any voltage is to induce a differential temperature on those two opposed sides. This is the basic physics of thermocouples you can’t argue against this, so the sensor of the IR thermometer MUST, I repeat MUST, be cooled on its exposed side to the target.
Have a nice day.
Massimo
Hoops! “when the input slit is aimed to a target colder than the IR thermometer itself the exposed face of the sensor MUST be cooled by the (reduced) radiation outgoing net flux of the input slit.”
Read incoming instead of outgoing.
My God Greg! I did it again, take account that I wrote my message here during the office break times, so I sometime I write erroneous statement.
When I referred to the iron on one side and the copper-nickel on the other side I was referring to the single thermocouple side, not the whole thermopile side.
Massimo, I think there is some misunderstanding in our discussion. Maybe we are talking about different points.
My main point is that there is apparently no experimental proof of the central warmists’ assertion about colder body reducing cooling of a warmer body by it’s IR radiation. The second point is that even if it is possible, it can be negligible and there is no proof that it is not negligible. This is relevant for the existence of the “greenhouse effect”.
Now, the question is whether the fact that IR thermometer can derive the temperature of a colder body from the colder body’s IR proves that this IR changes temperature of the receiving part of the sensor. I mean: no, it is not.
This is a logical issue in the first place. Look, we know that the sensor reacts to the radiation of colder (and warmer as well) bodies. We also know that IR from warmer bodies also increases temperature of the receiving part of the sensor. But from this alone we can not conclude that the IR from colder bodies changes the temperature of the receiving part of the sensor. It is still possible that 1) a warmer body sends it’s IR to the sensor AND changes it’s temperature and 2) a colder sends it’s IR to the sensor but DOES NOT change it’s temperature.
I mean, in both cases remote temperature measurement is possible, because of changes of electric current in the sensor but this effect can not be automatically attributed to changes in temperature if the target is COLDER.
Your argumentation is essentially “But it works this way!”. Sorry, I do not see it proven.
The Pictet’s experiment does not prove influence of a colder body’s IR on a warmer body either and is therefore irrelevant.
Dear Massimo PORZIO,
Let us consider the hypothetical scenario, as you and the climate models suggest, that there are back-radiations from the atmosphere to the warmer surface. What is the nature of the external energy or work that is required to drive the back-radiations from the colder atmosphere to the warmer surface? Sincerely, Nabil.
Hi Greg,
—My main point is that there is apparently no experimental proof of the central warmists’ assertion about colder body reducing cooling of a warmer body by it’s IR radiation.—
Uhmmm… Or you did my very same mistake or it could be I misunderstood what you said (maybe I’m Italian and my English is not so good). Did you mean “the central warmists’ assertion about colder body INCREASING cooling of a warmer body by it’s IR radiation.”? In Pictet’s experiment is a colder body that INCREASE the cooling of a warmer one by substituting the environment heat sinking, because this last is supposed warmer.
You say —Your argumentation is essentially “But it works this way!”. Sorry, I do not see it proven.—
No, I used many times thermocouples in some my designs in the past and probably I’ll use them again in the future. I’m not the one who say “But it works this way!”. The thermocoupes are the very core of the thermopile sensor inside an IR thermometer. I’ve two IR thermometers, if you have at least one, I suggest you to open it and you’ll find nearby the thermopile a small drop-shaped component which is a thermistor. That is a resistor which changes it’s value in temperature following a specific curve. Then ask yourself why the manufacturer put that sensor there (note that if your IR-thermometer is very precise, maybe that thermistor is a platinum base one, so it could be shaped as a rectangular white alumina plate).
The thermocouple works this way, as this very simple essay states what I told you before:
http://www.sterntech.com/pdfs/thermocouples.pdf
There is no way for a thermocouple to report any voltage other then the temperature at the measuring point must be different from the one at the so called “cold junction” (which is not necessarily colder than the measuring point, it has named this way just by convention because usually a thermocouple is used for measure places hotter than the environment).
I can accept that my explanation that I did in a previous post could be not precise. That is, it could be that in the reality the temperature of the side of the sensor which is exposed to the input slit could be kept higher than the other side at the environmental temperature. That’s because having the polyethylene fresnel lens a temperature its own, maybe that the exposed side of the sensor will never reach the opposite side temperature, except in case the IR thermometer is aimed to a zero Kelvin target (which is impossible of course).
But when you put a target colder than the environment in front of the IR thermometer slit you cool that side, because the outgoing net flux is increased respect the case of aiming the environment.
Have a nice weekend
Massimo
Hi Nabil,
“Let us consider the hypothetical scenario, as you and the climate models suggest, that there are back-radiations from the atmosphere to the warmer surface.”
I don’t suggest that (I’m no way a warmist), I never talked about “back”, but just radiation.
I believe that I’ve been clear, I admit that pointing the IR thermometer doesn’t mean that it’s a proof of any back-radiation. That is I believe it’s just a radiation coming from a mass of gases which have their own temperature. I never supported the idea that the gases radiation is all coming from the ground.
“What is the nature of the external energy or work that is required to drive the back-radiations from the colder atmosphere to the warmer surface?”
In my own opinion I believe (yes it’s just a believing, I always stated that, I’m still looking for any “proof”) that the part of IR radiation which really heat the IR thermometer sensor, could be the one which entered the atmosphere by direct sunlight conversion (see water vapor absorption in the so called short wave band).
Maybe that condensation of WV at higher altitudes plays a role in that IR emission.
But, I’m just an electronic engineer. My job is design electronic board, this is just a game for me. My be I missed a very important detail which void my statements.
Have a nice weekend.
Massimo
Massimo PORZIO says: “There is no way for a thermocouple to report any voltage other then the temperature at the measuring point must be different from the one at the so called “cold junction”…
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This misses the point a little bit. Again, it is about what effect COLDER bodies produce. And I do not mean replacement of a WARMER target with a colder one, but replacement of a COLDER target with a colder one.
If change in temperature causes change in voltage, it does not necessarily mean that ONLY change in temperature causes change in voltage. This “ONLY” needs to be proven. Like by direct experimental temperature measurements and comparisons, for example, when targets are colder. Maybe colder bodies just sent different amounts of IR to the sensor without making differences in temperature of the receiving part and these differences in IR cause difference in voltage.
Are such experiments known to you? Because no warmist on different blogs I talked to was able to present something real.
Hi Greg,
—If change in temperature causes change in voltage, it does not necessarily mean that ONLY change in temperature causes change in voltage.—
if you were right, then all the measurements done till today in the industrial control were not effective.
I mean: if it was true that something else than temperature (say IR not thermal radiation) changes significantly the voltage across the junction then the junction could not be used to measure the temperature at all.
In fact most temperature related industrial controls use thermocouples instead of thermistors. That’s because despite they are less precise they are cheaper and in most cases their precision is more then enough for the industrial goals. But in that use thermocouples always had been (and are) effective in measuring colder targets as warmer ones.
This should lead you to understand that even colder targets changes the temperature at the junction.
Have a nice Sunday
Massimo
Massimo PORZIO says: “Hi Greg,
—If change in temperature causes change in voltage, it does not necessarily mean that ONLY change in temperature causes change in voltage.—
if you were right, then all the measurements done till today in the industrial control were not effective.
I mean: if it was true that something else than temperature (say IR not thermal radiation) changes significantly the voltage across the junction then the junction could not be used to measure the temperature at all.”
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Temperature is not measured by IR thermometers, it is voltage that is measured. Then the temperature of the remote target is calculated, derived from the voltage measurements. So, your argumentation is based on something what needs to be proven.
Radiation from colder targets causes changes in voltage? Apparently, no problem with that. But the second point of yours “radiation from colder targets causes changes in temperature as well” needs to be proven.
And you can not prove that just by assuming “it does”.
@Greg,
Just to explain better my thought about.
Imagine to have a thermocouple attached to a first body. That body has its own temperature that we know thanks to that thermocouple. Say that the temperature of that body is caused by the incoming energy of an electric heater and by its dissipation of the body in the surrounding environment which is colder than this first body. Now imagine to place a second colder body nearby the the first one which is colder than the surrounding environment. The second body is kept coder than the environment by the work done by a thermal pump.
If your assumption about thermocouples was true, we should expect a reduced temperature reading by the thermocouple, while the first body shouldn’t cool at all, because following your argumentation if the thermocouple is not cooled also the first body shouldn’t, are they both made of solid matter, and are they both exposed at the same IR fluxes, or not?
If it was that case then the thermocouple failed to reports the temperature.
The direct experience of everyday demonstrates that’s not.
Again have a nice Sunday.
Massimo
Massimo PORZIO says: “@Greg,
Just to explain better my thought about.
Imagine … a first body…the temperature of that body is caused by the incoming energy of an electric heater…a second colder body …is kept coder than the environment by the work done by a thermal pump. … …”
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Massimo, with electric heating and electric cooling you can achieve whatever effect you want.
To your “imagine”. Interestingly, warmists who I asked to present an experimental proof for their key assertion presented nothing and did not admit there was nothing, but instead they advised me to do experiments myself or gave me so called “thought experiments” where I should have imagined things.
Sorry, this is not really scientific.
Hi Greg,
—To your “imagine”. Interestingly, warmists who I asked to present an experimental proof for their key assertion presented nothing and did not admit there was nothing, but instead they advised me to do experiments myself or gave me so called “thought experiments” where I should have imagined things.—
I don’t know who you are, anyways here is a professional having 23 years of experience in industrial controls designs who switched last year to industrial redundant safety radio remote controls designs.
About my “imagine”: that’s the real world, I often had to work with thermocouple based control systems even of high power, which involves some thermodynamic computations to keep safe the power electronics. The “imagine” was for you, because I don’t know what’s your background, for me (believe it or not) it was and it’s still real experience.
You are the one ho suggested the possibility that a thermocouple can produce a change in voltage across its junction without any changes of its temperature, not me. Since the one I always supported in this discussion is the very basic behavior of a thermocouple, so you are the one who should demonstrate your statement, not me negate it.
I don’t know what to say more, it seems that you don’t see the difference from the real world and your “supposed to work world”, so is much better we end this here.
Just to tell, I’m not the one who want to know everything. Few years ago on this very same blog, one pointed out to me an error about the possibility that a predominant positive feedback based can’t be stable, I went to the books of the time of school and after I read that I was wrong, I returned here and I thank him to having corrected me, and I said him “yes you are right and I was wrong”, but I assure you that this is not the case.
Have a nice day.
Massimo
Massimo PORZIO says: “here is a professional … You are the one ho suggested the possibility that a thermocouple can produce a change in voltage across its junction without any changes of its temperature, not me. Since the one I always supported in this discussion is the very basic behavior of a thermocouple, so you are the one who should demonstrate your statement, not me negate it.”
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This is not quite correct.
My point is that there are 2 possibilities, and you maintain there is only one but can not prove it. So, the second possibility is, you know, possible, and therefore your thesis remains unproven.
Sorry, but arguments like “I know for sure” or “I am a professional” are absolutely invalid in a scientific debate.
Until now no one I talked to on various blogs has been able to present a link to a real experiment proving that same key assertion of the warmists’.
—My point is that there are 2 possibilities, and you maintain there is only one but can not prove it.
So, the second possibility is, you know, possible, and therefore your thesis remains unproven.—
No you invented a possibility and you must show me that it really exist.
I already explained you that if your “second way a thermocouple junction produces voltage change without any temperature change” (which is just your own believing, there is no scientific documentation that proves your statement), the thermocouple should never be useful to measure temperatures at all because its voltage was a function of two different and independent variables. Since we use the thermocouples to measure the temperature you are WRONG.
If I would follow your very personal believing about how the science works, I could tell you: no there are three ways the thermocouple produces voltages across its junction… No wait, there are infinite ways indeed… Now is you that must demonstrate me that are only two instead!
Obviously science don’t works this way, because science is the pursuit of the truth of how the things works in nature.
Warmist are wrong when they use statistical methods to proves or disproves as they prefer the existence of a theory which has never been observed in nature and if exist is so minimal that it has been ignored for a long time.
Thermocouples instead measure the temperature because they produces a voltage only because their junction voltage is proportional to its temperature and only it. This is proven by a couple centuries of their use in temperature measurements. It’s not a simple theoretical illation, like “they produce voltage just by IR non thermal exposure if the target is colder” which means absolutely nothing. Because a junction of two different conductors produces a voltage (even minimal or infinitesimal), just few tenth of degrees above the absolute zero, and its voltage start to rise as its temperature rise even a little above -273.2°C.
Have a nice day.
Massimo
Massimo PORZIO says: “I already explained you that if your “second way a thermocouple junction produces voltage change without any temperature change” (which is just your own believing, there is no scientific documentation that proves your statement), the thermocouple should never be useful to measure temperatures at all because its voltage was a function of two different and independent variables. Since we use the thermocouples to measure the temperature you are WRONG.”
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First, my statement is that you has not proven YOUR statement and since no one else (probably) has, the key assertion of warmists’ remains unproven. You are not trying to reverse the burden of proof, are you?
Second, again, IR thermometers do not literally measure temperature of remote objects, they CALCULATE it. IR thermometer receives IR from the target, the IR causes changes in voltage, those changes in voltage are measured and then the temperature of the target is CALCULATED.
If you mean that IR from a colder targets causes changes in temperature in the warmer sensor (apart from by replacing a warmer target), then prove it. So simple is that. Just repeating “only” is not a proof, you know.
Prove it scientifically. You only need to present a link to a real scientific experiment proving that.
@Greg
—First, my statement is that you has not proven YOUR statement and since no one else (probably) has, the key assertion of warmists’ remains unproven.—
I still haven’t understood which should be my statement you are referring to, because no one here have ever told that colder bodies warmed by a warmer one, can warm back more this one.
—Second, again, IR thermometers do not literally measure temperature of remote objects, they CALCULATE it. IR thermometer receives IR from the target, the IR causes changes in voltage, those changes in voltage are measured and then the temperature of the target is CALCULATED.—
It’s like I wrote all my previous posts for nothing. The very last words I’ve to tell you is: instruct yourself by searching how an IR thermometer works. I have many other important things to do than teach you that, since it seems that you are not interest to understand the very simple physics at the core of that devices.
—If you mean that IR from a colder targets causes changes in temperature in the warmer sensor (apart from by replacing a warmer target)—
yes it is exactly this last “exception”, dear Greg, that you seem to don’t understand.
We live in a matter made environment, so when you point to a colder target you move from the warmer matter of the surrounding environment to the colder body, so yes IR from a colder targets causes changes in temperature in the warmer sensor (it reduces). So the only, ONLY, variable that induces a change in the voltage across the junction of a thermocouple is… The temperature change.
No other comments.
Open your mind,
Have a nice day
Massimo
P.s. I never been a warmist, I still haven’t found any proof of self heating back radiation, but it could be that one day someone give me that proof.
Who can tell? Maybe I’m wrong.
Massimo PORZIO says: “—If you mean that IR from a colder targets causes changes in temperature in the warmer sensor (apart from by replacing a warmer target)—
yes it is exactly this last “exception”, dear Greg, that you seem to don’t understand.
We live in a matter made environment, so when you point to a colder target you move from the warmer matter of the surrounding environment to the colder body, so yes IR from a colder targets causes changes in temperature in the warmer sensor (it reduces).”
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A have to apologise for possibly causing some misunderstanding. By “warmer target” I meant “warmer than the sensor” and by “colder targets” I meant “colder than the sensor”. Meaning the receiving part of the sensor.
A “warmer than the sensor” target warms the sensor indeed, so here you are right, if you replaced a “warmer than the sensor” target by a “colder than the sensor” one, the temperature of the sensor would decrease. This is what the Pictet’s experiment is about, no problem with that.
Now, if we consider only “colder than the sensor” targets and replace one with a even colder one, then the sensor will receive less IR, this is clear. By equal emissivity, of course. The question is whether the temperature of the sensor would decrease as well or not. Note, both targets are colder than the sensor.
And now my point again: we know that such a replacement causes change in voltage, no problem with that either. But I do not see as proven that that such a replacement causes CHANGE IN TEMPERATURE of the sensor as well. That is the point. It is not that I think it does not, not at all, it is about “proven-unproven”.
If you mean “yes, it does”, you are welcome to prove it experimentally. Just provide a relevant link, that is all. Again, arguments like “this is the only way” or “I know for sure, I am a professional” are nor really scientifically valid, you need to understand that. And, of course, it is not about explaining the thesis or “teaching” anybody. It is about PROVING.
Hi Greg,
what depress me is having failed to make you understand that if a thermocouple changes his voltage across its junction because of a so called “not thermal IR radiation”, it became useless for measuring the temperature.
Any thermocouple type has its own trans-characteristic curve T/V which is not linear but it is well known and unique for any particular type.
See this Analog Device datasheet about two signal conditioner for K and J thermocouples:
http://www.me.psu.edu/rahn/me462/AD594_5_c.pdf
As you can see there, on page 3, you can find the V/T table specified @25°C. Note that the table ranges from -200°C to 1250°C for the K type and a little less for the J one (750°C).
Just to say, note also that they did a mistake and swapped the input voltages with the output voltages columns!!!
It’s the signal conditioner output that returns 0V at 0°C of course not the thermocouple 🙂
So, as you can see there, any voltage has it own correspondent temperature. It doesn’t matter of any other “IR non thermal radiation”. If it was true that that sensors was affected by such kind of radiation, they had to specify in that table at which radiation level the very same table was compiled, and they had to specify how that table changed as function of the non thermal IR radiation. The simple fact that those specifications are omitted should make you understand that the IR non thermal radiation doesn’t change the voltage across the junction.
Have a nice day.
Massimo
Massimo PORZIO says: “Hi Greg,
what depress me is having failed to make you understand that if a thermocouple changes his voltage across its junction because of a so called “not thermal IR radiation”, it became useless for measuring the temperature. … See this Analog Device datasheet about two signal conditioner for K and J thermocouples:
http://www.me.psu.edu/rahn/me462/AD594_5_c.pdf
So, as you can see there, any voltage has it own correspondent temperature.”
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Yeah, change of temperature causes change of voltage. Did I dispute that? No, I did not. But no problem, you may repeat it as long as you like.
Thank you for the “device datasheet”. This is the second irrelevant link you gave, the first one was about Pictet’s experiment.
I do not know what “not thermal IR radiation” is. I question, however, the alleged effect of the IR radiation from colder bodies on temperature of warmer bodies. Because I have not seen a real scientific experimental proof. Your “thermocouple becoming useless” argument is in fact a variation on the same unproven thesis, therefore it does not contribute to proving that thesis.
You need to come up with something real and relevant, if possible.
P.S. I am glad you have come back after your “No other comments”-promise.
Roy is pleased that his page on the Greenhouse effect gets the most hits – thus misleading more school children and adults of the future.
Roy would do well to read Joe Postma’s October 2012 paper from which I quote (p. 49) …
“Greenhouses do not create heat; they simply trap heated air…air which is heated through contact with objects that are heated by sunlight. The atmosphere does not trap heated air because it isn’t a physically rigid barrier – it is a gas and so it naturally flows and cools heated objects. Greenhouses do the opposite of what the open atmosphere does. The atmosphere does not cause heating via its back-radiation because there is no evidence that this occurs, and this is not how a real physical greenhouse functions in any case. If a real physical greenhouse cannot heat by backradiation,then neither can the atmosphere. Trapped radiation cannot heat itself up and increase its own spectral temperature; radiation with a spectral temperature of -180C will always be radiation of a -180C spectral temperature, and this radiation cannot induce heating above its own spectral temperature nor can it interact with itself to increase its own “Wein-peak” frequency. This is probably related to a fundamental restriction from the Laws of Thermodynamics. Radiation cannot increase its own temperature, nor the temperature of its own source.”
Hi Greg,
Still here:
—Yeah, change of temperature causes change of voltage. Did I dispute that? No, I did not. But no problem, you may repeat it as long as you like.—
No, it’s not that the point, it’s that ONLY change of temperature causes change of voltage in thermocouples, so your hypothesis is wrong, that’s the point.
Even if it was true that “there must be some other cause that produces a voltage”, that must be negligible, otherwise they had never been used for temperature measurements.
About: —I do not know what “not thermal IR radiation” is.—
You wrote: —The fact is, that IR from the object produces some electrical changes in the detector and these changes are measured, not the ones in detector’s temperature.—
In my opinion, for an IR thermometer this means an IR radiation which doesn’t change the temperature of the thermopile.
—P.S. I am glad you have come back after your “No other comments”-promise.—
I’m a little busy indeed in these days, and I’ve not so many time to write here.
Have a nice day.
Massimo
Massimo PORZIO says: “it’s that ONLY change of temperature causes change of voltage in thermocouples, …otherwise they had never been used for temperature measurements.”
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We have had this unproven “only” a few times, repeating it does not make a valid argument.
As for the unproven”otherwise”-argument, this is essentially the same unproven thesis put in a different way. Well, you are welcome to prove it in this form, why not. But without a real proof it remains, you know, unproven.
Greg,
—Well, you are welcome to prove it in this form, why not. But without a real proof it remains, you know, unproven.—
I already told you that you suggested that new behavior of the thermocouple, so are you the one who should demonstrate it is true, not me it is false.
Just to know, how does “your IR thermometer” discriminate the real temperature from the other source of voltage across the
thermocouple junction?
Two sources of voltage, one heat the junction, but the other not… What is useful for that voltage?
Massimo PORZIO says:
“Greg,
—Well, you are welcome to prove it in this form, why not. But without a real proof it remains, you know, unproven.—
I already told you that you suggested that new behavior of the thermocouple, so are you the one who should demonstrate it is true, not me it is false.”
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I do not know anything about any “new” behavior. I simply do not see your version or your explanation as proven.
Your arguments are essentially “only” and “otherwise”, but you failed to prove both of them. You can not really prove anything by simply referring to other unproven assertions, you really need to understand that.
It is not that your version is apparently unreasonable, so I can understand that you like it and your confusion, but, as I said, it is unproven.
Hi Greg,
you behave like a very famous comic actor of the 60s named Totò, his very name was Antonio De Curtis indeed and make many movies.
He was specialized in funny gags where he started saying a silly thing and after a couple of cues with his stooge he reverted the responsibility of his own statement to the stooge himself, blaming him for his stupidity saying that silly thing.
Ok, I submit to your very special interpretation of what science it is.
Be sure: next time, that I’ll need to design some board which involves a temperature measurement via thermocouples I would remember of you.
I’ll do that ignoring any possible other way a thermocouple produces any voltage not correlated with its own temperature, and I’m sure that that board will work great anyways as always did my boards 😉
Have a nice day.
Massimo
Massimo PORZIO says:
“Hi Greg,
you behave like a very famous comic actor of the 60s named Totò, his very name was Antonio De Curtis indeed and make many movies.”
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Come on, Massimo, all what you have presented are 2 irrelevant links and a lot of “explanations”. This might be enough for you to believe whatever you want, but a scientific debate is something different. Maybe you do not fully understand the difference between a fact and a fiction.
In real science an unproven thesis is not considered to be a proven fact.
Massimo PORZIO says:
“Be sure: next time, that I’ll need to design some board which involves a temperature measurement via thermocouples I would remember of you.
I’ll do that ignoring any possible other way a thermocouple produces any voltage not correlated with its own temperature, and I’m sure that that board will work great anyways as always did my boards ;)”
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A patient reader might have noticed that in the course of this debate you have been conspicuously silent on how exactly the IR radiation of colder targets (colder than the receiving part of the sensor) increases the sensor’s temperature if one switches to less colder (but still colder than the receiving part of the sensor) target. By equal emissivity, of course.
I suggest you come up with something real or admit that there is nothing to come up with. Another possibility would be, of course, that there is some change in temperature, but it is so absolutely negligible that it would blow up the whole “greenhouse gasses warming” immediately.
You see, I am still open to any outcome, but you need to present something tangible, verifiable, you know, something scientific.
Greg,
—This might be enough for you to believe whatever you want, but a scientific debate is something different. Maybe you do not fully understand the difference between a fact and a fiction.—
Facts are the temperature measurements we did, do and will do in future using a thermocouple. Facts which imply that except for the Seeback effect, there are no other cause for the voltage across the thermocouple junction than the absolute temperature of the junction itself.
The day you’ll demonstrate that there is another cause to have that voltage, some students probably will read the name Gregory House (or what ever is your real name) nearby Thomas Johann Seebeck in their textbooks of physics. For the moment it’s your assumption that is just “fiction”.
—A patient reader might have noticed that in the course of this debate you have been conspicuously silent on how exactly the IR radiation of colder targets (colder than the receiving part of the sensor) increases the sensor’s temperature if one switches to less colder (but still colder than the receiving part of the sensor) target. By equal emissivity, of course.—
Easy: since the environment where the sensor is placed it’s warmer of the sensor and the target. The temperature of the exposed side will rise a little because of the thermal resistance of the sensor thickness due to the reduced flow of energy in it, which is induced by the minor delta T from the target and the environment.
To make an everyday example, place a differential thermometer with one sensor on the inner surface of the glass of one window and the other sensor on the outer surface of the same glass. When the inner temperature of the room is taken at a constant value, say 20°C, guess what the inner and outer sensor read when the outer colder temperature changes from 0°C to 10°C.
The answer is: the delta T reduces.
That delta T, it’s the thermal resistance of the glass multiplied by the power flux which is outgoing from the room.
Just, physics.
And it is exactly what happen in a thermopile array of thermocouples in an IR thermometer in the case you suggest to be impossible. The only difference is that in the IR thermometer the radiation perform better because one side of the sensor is placed in the optical path of the lens. For this the Pictet’s experiment is relevant, despite what you believe.
Do you get it now?
—I suggest you come up with something real or admit that there is nothing to come up with. Another possibility would be, of course, that there is some change in temperature, but it is so absolutely negligible that it would blow up the whole “greenhouse gasses warming” immediately.—
Still nothing to come up from me, I NEVER said I believe in any “greenhouse gasses warming” (for the moment).
Have a nice day
Massimo
Massimo PORZIO says: “Greg,
—A patient reader might have noticed that in the course of this debate you have been conspicuously silent on how exactly the IR radiation of colder targets (colder than the receiving part of the sensor) increases the sensor’s temperature if one switches to less colder (but still colder than the receiving part of the sensor) target. By equal emissivity, of course.—
Easy: since the environment where the sensor is placed it’s warmer of the sensor and the target. The temperature of the exposed side will rise a little because of the thermal resistance of the sensor thickness due to the reduced flow of energy in it, which is induced by the minor delta T from the target and the environment.”
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Well, I understand that English is not your first language, so no problem, but I have to guess what you meant.
I guess, by your “Easy: since the environment where the sensor is placed it’s warmer of the sensor and the target” you meant “”Easy: since the environment where the sensor is placed IS warmer THAN the sensor and the target”. If my guess is correct, you completely missed the point.
Look, I specifically addressed a case, where you have 2 targets and both of them are colder, than the sensor, and you switch between them.
So, please, read it again: “A patient reader might have noticed that in the course of this debate you have been conspicuously silent on how exactly the IR radiation of colder targets (colder than the receiving part of the sensor) increases the sensor’s temperature if one switches to less colder (but still colder than the receiving part of the sensor) target. By equal emissivity, of course.”
The emphasis lies on “HOW EXACTLY”. I mean by that REAL EXPERIMENTAL DATA demonstrating this ALLEGED INCREASE IN THE SENSOR’S TEMPERATURE. It is all about science, Massimo, and not about impressions, beliefs and “explanations”.
Please, do not bother to refer to Pictet’s experiment again, because it is about a different (and irrelevant) case.
My guess is that nobody, including you and our dear host, will come up with the real data. And a possible explanation might be that this temperature increase is either ZERO or ABSOLUTELY NEGLIGIBLE, and in both cases the “greenhouse effect”-concept will be blown up immediately and apparently for every layman.
I Greg,
I don’t play no more.
Just have nice days.
Massimo
I’m smarter then all of you!