As readers may know, Dr. Roy Spencer and I have had a long running disagreement with the group known as “Principia Scientific International” aka the Sky Dragon Slayers after the title of their book. While I think these people mean well, they tend to ignore real world measurements in favor of self-deduced science. They claim on their web page that “the Greenhouse gas effect is bogus” and thus ignore many measurements of IR absorptivity in the atmosphere which show that it is indeed a real effect. Rational climate skeptics acknowledge that the greenhouse effect exists and functions in Earth’s atmosphere, but that an accelerated greenhouse effect due to increased CO2 emissions doesn’t rise to the level of alarm being portrayed. Yes, there’s an effect, but as recent climate sensitivity studies show, it isn’t as problematic as it is made out to be.
I don’t plan to get into that issue in this thread, as this is an hands-on experiment showing one of the thermal premises of the “slayers” in action to prove or disprove it. Most of what that group does is to spin sciencey sounding theories and pal reviewed papers by a mysterious members-only peer review system, and I have yet to any one of them try to do anything at an experimental/empirical measurement level to back up the sort of claims they make.
What started the recent row was an essay by Dr. Spencer titled Time for the Slayers to Put Up or Shut Up, which I followed on with: The Spencer Challenge to Slayers/Principia.
In their response to Dr. Spencer, they made this essay…
…and in that response was this curious graphic from Dr. Alan Siddons:
To be honest, I laughed when I saw this, because for all their claims to be “experts” on thermodynamics while telling the world that “back radiation” has no effect, this is a clear-cut case of them not knowing what they are talking about when it comes to heat -vs- visible light. Clearly, you can indeed reflect/re-emit a portion of the visible and infrared energy back to the light bulb, energy which would have been lost to the dark surroundings. There is no “extra” energy per se, just a spatial redistribution of energy (a greenhouse atmosphere has higher temperatures near the surface, but lower temperatures at high altitudes). They also seem to fail to understand how a mirror actually works, bold mine:
“Does shining a flashlight at a mirror so that all the radiation comes back to the flashlight make the flashlight shine brighter?”
While the emissivity of a glass mirror is high, no mirror reflects 100%, and mirrors of course are not lossless, so it will also absorb some Visible and IR in addition to reflecting/re-emitting some of it back. You can see this loss of energy in the FLIR camera in the video just before the mirror is removed at about 16:30.
I put their claim of “a light bulb facing a mirror does not heat up” to the experimental test.
I did several spot experiments at home over the last couple of weeks to investigate the issue empirically (since talk is cheap), and to make sure it was repeatable, while discussing the design and results with Dr. Spencer. The first two designs of the experiment had weaknesses that I was not happy with, and so it has take time to devise an experiment in a way that was fully comprehensive and uninterrupted from start to finish. For example, in my first iteration, the experiment was shot from the side (similar to the diagram), but required rotating the bulb mount assembly away from the mirror to get the temperature of the bulb surface. This wasn’t always repeatable to get the same spot on the bulb surface and it introduced variances. Another problem was that standard household bulbs had odd temperature gradients across their surface due to the way the filament is placed. The flood lamp was much more repeatable at its center. Repeatability is important, because I want others to be able to replicate this experiment without significant variances due to the equipment and how it is setup.
After ensuring the experiment works, and is repeatable/replicable, and that the control run without a mirror performed as expected, today in this WUWT-TV segment, I present the entire experiment uninterrupted as one long video. It is almost 21 minutes long, but I had no choice, because at least 16 minutes of it were required to be non interrupted to show the experiment in progress. I didn’t want anyone to be able make silly claims that the experiment was faked that there were video edits going on to change the results, such as Al Gore did in his Climate 101 video.
In my case, I did some graphic overlays to illustrate points and data, but there was no discontinuity edits of the video or audio from start to finish.
Here’s the experiment equipment list and procedure.
Equipment:
- FLIR BCAM portable infrared camera
- 65 watt incandescent flood lamp (used due to mostly flat center target surface)
- clamp on ceramic lamp base and metal electrical base/stand
- small glass wall mirror from K-Mart
- video camera to record the event
Procedure:
- Setup equipment in similar fashion to Alan Siddons figure 3 above, using stands and clamps to allow for correct height and continuous recording of FLIR camera image and a timer image.
- Focus FLIR on flat front surface of 65 watt bulb
- Start video camera to record experiment, simultaneously start digital timer
- Apply AC electrical power to 65 watt bulb
- Note FLIR temperature of bulb center surface at intervals, record that data.
- Run until equilibrium temperature is reached, which I defined would be when temperature no longer increases after a period of about 60 seconds, note that temperature, note how long that takes with timer. Record that data.
- Leaving all equipment in place and operating, place mirror perpendicular to 65 watt bulb surface, at about 3 inches away to fit scale of Alan Siddons Figure 3. This will obscure surface of bulb from FLIR camera but is required so that distance/position between bulb and FLIR is not changed, which could result in altered readings.
- Continue experiment.
- Show with video camera how equipment remains in place.
- Wait for the same amount of time as previous equilibrium temperature took to reach.
- Remove mirror, note on the FLIR camera what the surface temperature of the 65 watt light bulb is at that time.
Premise of the experiment:
If the temperature recorded by the FLIR camera is the same after the mirror has been left in place for the amount of time that it took to reach equilibrium temperature, then the Principia/Slayers claim is true.
If the temperature has risen, it falsifies their premise that “a light bulb facing a mirror does not heat up”.
Video of the experiment (with conclusion) :
Note that this is not a big budget production (it was done in the dining room of my home) so I apologize for less than perfect audio quality. BTW, the clothes iron I used as a prop was not turned on, which is plainly evident in the FLIR image. It just so happend that the tabletop ironing board and iron worked out well to position the mirror…. and I had no budget beyond a few dollars for light bulbs and lamp bases. Where’s that big oil check when we need it? /sarc
Plotted temperature data:
[Note: per a suggestion in comments, this graph was updated to show the data after the “mirror added” as dashed line, since only one datapoint (228F) was measured. – Anthony]
Supplemental information:
In a PDF file here: Slayers_lightbulb_experiment
- Temperature data recorded from the experiment to reach equilibrium temperature
- Graph of the data recorded from the experiment showing data including after removal of mirror.
- I also ran a separate control experiment for 2x of the tested equilibrium temperature time to see if bulb can reach same temperature without mirror. I’m satisfied that the experiment is properly functioning.
I have another experiment planned for part 2 that will test another claim that the Principia/Slayers routinely make. I’ll have that in a few days.
UPDATE: In the claim by Joe Postma at Principia where they stated a couple of days ago that we’d “cut and run” (obviously not, just taking our time to be careful) Alan Siddons makes this claim:
As PSI’s Alan Siddons laments:
“All of us on our side have researched and deeply pondered the actual principles of radiative heat transfer. On the other side, however, the “experts” we argue with, like Spencer, Lindzen, Monckton, Watts, just insist that a body’s radiant energy can be doubled by directing that energy back to it — even though the simplest of experiments will shows that this is false.
I’ve never made a doubling claim like that, nor am I aware that any of the others named have claimed a doubling, only that some energy will be returned, as I have just proven in the “simplest” mirror experiment postulated by Siddons.
I have to think these folks aren’t operating with a full understanding of what the physical basis is when I read things like this. This is an excerpt of this comment left in the thread below by Joe Olson where he confuses a microbolometer with doppler radar:
“Remote read IR thermometers are also used to ‘explain’ this back-radiation warming effect. These instruments work be sending out an IR signal and measuring the shift in the returned signal. ” (bold mine -A)
No, sorry, you are 100% wrong. it is a passive sensing device. No active signal is emitted.
FIGURE 1. One pixel in a microbolometer array. An infrared-absorbing surface is elevated above the substrate and thermally isolated from adjacent pixels. Low mass increases the temperature change from heat absorption. Read-out circuits typically are in the base layer, which may be coated with a reflective material to reflect transmitted IR and increase absorption of the pixel. http://www.laserfocusworld.com/articles/print/volume-48/issue-04/features/microbolometer-arrays-enable-uncooled-infrared-camera.html
Gosh, I didn’t think your misunderstanding of an IR bolometer was that distorted. No wonder you guys make the sort of way out claims you do.
A microbolometer is a specific type of bolometer used as a detector in a thermal camera. It is a grid of vanadium oxide or amorphous silicon heat sensors atop a corresponding grid of silicon. Infrared radiation from a specific range of wavelengths strikes the vanadium oxide and changes its electrical resistance. This resistance change is measured and processed into temperatures which can be represented graphically. Source: http://en.wikipedia.org/wiki/Microbolometer
You should really quit while you can Joe, you are making a fool of yourself when you make such claims that are so easily disproved. – Anthony
UPDATE3: The Principia/Slayers group has posted a hilarious rebuttal here:
http://principia-scientific.org/supportnews/latest-news/210-why-did-anthony-watts-pull-a-bait-and-switch.html
Per my suggestion, they have also enabled comments. You can go discuss it all there. – Anthony
Greg not understanding the existence (let alone the intricacies) of EM (Electro-Magnetic) energy in the radiative transfer of what we would term ‘thermal’ (LWIR) energy would explain his continued behavior; his neighbor’s dog doesn’t have any grasp of the EM domain either … sort of a ‘cargo cult’ attitude must exist, one turns a knob, the TV comes on, and a picture appears on the screen – one need not understand the underlying applied science(s) or one IOTA of ElectroMagnetics to buy, operate and enjoy a TV (or radio) set, but it would help a bit if -and when- arguing the finer points of radiative energy transfer …
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David says (May 27, 2013 at 9:16 pm): “An interesting thought experiment is what would happen in an atmosphere with zero GHG.”
http://www.drroyspencer.com/2009/12/what-if-there-was-no-greenhouse-effect/
How does frost form, Morris, when air temperatures might still be hovering around 35 deg F.?
How come that same frost doesn’t form when clouds form (or move in) overhead? Bear in mind the temperature ‘up there’ (in the clouds) can be well below freezing too.
Not saying you’re wrong, just that there is more to consider overall (like radiative energy transfer which occurs in the EM or ElectroMagnetic domain at various wavelengths versus simply ‘vibrating molecules’ -as in a solid- ‘bumping’ into each other at a more or less rapid rate as the temperature changes.)
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[snip – take your ad hom claims of amateurish elsewhere, like over to Principia, where the experiment was designed – mod]
I see lots of insult flying around – don’t think that contributes much to anything.
How about this.
209 degrees F is more than 98 degrees C or 371 Kelvin. The flux emitting from the glass is of the order of 1080 Watts per square metre.
At the end the temperature was 228 degrees F or about 109 degrees C or 382 K. The flux emitting from the glass is of the order of 1208 Watts per square metre.
With the mirror so close to the glass of the bulb the reflection back has to be far in excess of 50%.
If 1079 W/square metre plus say 50% or more can induce a mere 10 K increase in temperature I’d say that goes a long way to proving that it is invalid to sum 2 distinct radiation fluxes and use that sum to calculate a valid temperature.
1079 plus say 50% gives a sum of ~1619 Watts per square metre which should induce a temperature of ~411 K – or ~280 degrees F – almost 30 K or 62 degrees F lower than recorded.
If an object at 209 degrees F, 98 degrees C or 371 Kelvincan only produce 10 K increase what chance … – well I’ll leave that unfinished.
Sorry “lower” should be “higher”.
Joseph A Olson says: “On the availability of ambient IR, first generation night scopes had x1,000 power, second x20,000 and third x50,000 power, yet all still required supplemental IR light, even using the full 700 nm to 1mm IR range, ”
Why do you insist a Night Vision scope requires supplement IR light when Night Vision scope functions primarily in visible light range (aka starlight moonlight).
Why do you keep mixing Night Vision scopes with IR Thermal (FLIR) scopes?
Do you not understand Night Vision and FLIR scopes are functionally different, have different purposes, and provide user with different information?
Gary Hladik says:
May 27, 2013 at 7:26 pm
Exactly. So why haven’t the so-called “slayers” done the definitive experiment that would prove them right and disprove the entire basis of the so-called “greenhouse effect”? They write endlessly, but do nothing. Pretty suspicious, no?
===
They did.
They waited 20 years, and with CO2 levels raging upward, contrary to ALL your predictions,
it cooled.
That is i.m.p.o.s.s.i.b.l.e. with GHE hypothesis.
The bulb was a whole 3 inches from the mirror, so there’s no loss in convection at all. In fact, the surface temp of the bulb is only lowered by the convection that touches the bulb surface.
Further, any reduced space around a curved surface creates a venturi, increasing airspeed and therefore convection.
[snip – take it to the slayers for designing a flawed experiment then – mod]
Rosco says (May 27, 2013 at 10:00 pm): “With the mirror so close to the glass of the bulb the reflection back has to be far in excess of 50%.”
Look at the video again. Before the mirror is added, say at about 6:00, we see the light illuminating part of the desk. This is of course only part of a hemisphere of illumination that won’t be reflected back to the lamp by the flat mirror.
At about 12:30, with the mirror in place, Anthony moves the camera, and at several angles we see light coming directly from the lamp to the camera, and reflected off the mirror to the camera; none of this is reflected to the lamp. Note also that reflected light from the mirror is illuminating the wall behind the apparatus, not the lamp. Moreover, as revealed by the hot spot behind the mirror, much of the lamp’s radiation heats the mirror, which then loses heat by convection and by radiation both toward and away from the lamp.
So it’s not at all obvious that “far in excess of 50%” of the lamp’s radiation is reflected back to itself. If anything, the experiment shows that only a small fraction of the lamp’s radiated energy is returned by the mirror.
To measure the power actually reflected to the lamp, presumably the experimenter could reduce power to the lamp until its temperature with mirror matches its temperature without. The difference should approximate the effective reflected power.
Donald L. Klipstein says
Compared to moist places, the desert’s lack of water vapor maximizes the adiabatic lapse rate. Heat from the surface is lost to space at an increased rate due to the increased vertical temperature gradient of the air, which in turn increases vertical convection, etc. A second possible reason is that the dry desert air feels cooler to a human. Greenhouse effect not required.
Steven R Vada says (May 27, 2013 at 10:20 pm): “They waited 20 years, and with CO2 levels raging upward, contrary to ALL your predictions,
it cooled.
That is i.m.p.o.s.s.i.b.l.e. with GHE hypothesis.”
Wow! What a great laboratory experiment!
So what happened on their control Earth? 🙂 🙂
[snip – Mr. Watts has made no claims of being an expert in radiometery as you assert, he’s simply replicated an experiment to show how it is problematic. If you don’t like the premise of the experiment, complain to the slayers as it is their design, but don’t make false claims about Mr. Watts because you have issues with claims he has not made. – mod]
H2O adds thermal mass because of condensation to a liquid.
CO2 does not alter the mass of any part of the atmosphere.
Gary Hladik says:
May 27, 2013 at 9:21 pm
David says (May 27, 2013 at 9:16 pm): “An interesting thought experiment is what would happen in an atmosphere with zero GHG.”
http://www.drroyspencer.com/2009/12/what-if-there-was-no-greenhouse-effect/
———————————————————————————————————————-
Gary,
Now that Anthony has effectively trashed the arguments of the PSI Assault Clowns, perhaps it is possible to discuss the real critical flaws in the failed radiative GHE hypothesis.
Dr. Spencer has got it wrong. Most of what he writes in the linked post is correct. In particular the critical role of radiative gases in tropospheric convective circulation. Dr. Spencer is also correct in saying that other than a near surface layer with substantial temperature variation, most of a non radiative atmosphere would trend to isothermal. However Dr. Spencer has made two critical mistakes, which combined invalidate the whole hypothesis.
The first mistake is assuming that the earth’s surface would have a substantially lower Tav under a non radiative atmosphere. As Anthony has shown by empirical experiment, reflected LWIR can slow the cooling rate of materials. My empirical experiments several years back at the Talkshop showed the same. However, my empirical experiments also showed that incident LWIR has no significant effect on the cooling rate of water that is free to evaporatively cool. This means that DWLWIR has no significant effect on the cooling rate of 71% of the earth’s surface. Surface Tav would be lower under a non radiative atmosphere, but not 33C lower.
Dr. Spencer’s most critical mistake is in claiming that other than the near surface layer in a non radiative atmosphere that – “The rest of the atmosphere would be at approximately the same temperature as the average surface temperature.” This is wrong, Wrong, WRONG! Simple empirical experiment shows that for a non radiative atmosphere, the temperature of the isothermal portion of the atmosphere would be set by surface Tmax NOT surface Tav. And that is not some general Tmax either. That would be spot Tmax such as desert surfaces and exposed liquid magma.
Dr. Spencer correctly points out that tropospheric convective circulation would stall without radiative gases. However, after the non radiative atmosphere, without strong vertical circulation, has gone isothermal, super-heating would then occur. Gases unable to return from altitude would be still adsorbing small amounts of UV, SW and IR. Because N2 and O2 are poor radiators, this would lead to super-heating just as in the thermosphere. Without radiative gases, our atmosphere would start to boil off into space. There are no planets or moons in our solar system that have managed to retain an atmosphere without radiative gases.
Radiative gases do slow the cooling rate of the land surface and absorb surface IR and heat gases in the lower atmosphere. However the cooling effects of IR radiation to space from the upper atmosphere and convective circulation cooling the day surface are far greater. The net effect of radiative gases in our MOVING atmosphere is cooling at all concentrations above 0.0ppm.
This thread was about an empirical experiment that others can replicate. Here are five other simple empirical experiments you can build and run yourself –
http://wattsupwiththat.com/2013/04/05/a-comparison-of-the-earths-climate-sensitivity-to-changes-in-the-nature-of-the-initial-forcing/#comment-1267231
-Experiment 1 shows that liquid water that is free to evaporativly cool does not respond to LWIR as other materials do, so the surface Tav under a non radiative atmosphere would not be 33C cooler.
– Experiments 2 & 3 are for those who do not understand the role of radiative gases in atmospheric cooling and convective circulation.
– Experiments 4 & 5 demonstrate that Dr. Spencer is wrong in claiming that the isothermal portion of a non radiative atmosphere would have its temperature set by surface Tav.
KevinK says: “The addition of the mirror changes the operating environment for the lamp The reflected energy does heat/warm the lamp filament The warmer filament has a higher resistance
Since you are operating with a constant voltage source (120 VAC), the current flowing through the lamp drops ”
With a drop in current flow, the watts being used has to drop too given constant voltage source.
Drop in watts being consumed by (or supplied too) bulb would cause a drop in bulb’s temperature. As in a 25 watt bulb won’t produce as much heat (85.3 BTUs) as 65 watt bulb (221 BTUs). The temperature didn’t drop with the mirror present, temperature instead went up.
Thus, try again on your claim that addition of mirror increased filament’s resistance.
{ I = W/V or 0.5416A = 65w/120v and R = V/I or 221ohm = 120v/0.5416A}
richard verney says:
May 27, 2013 at 11:54 am
I think I see here the cause of much of the misunderstanding in this thread. NB: photons do not have a temperature. One can talk loosely about the typical temperature at which a certain photon might be radiated (e.g. where the maximum of the black bode emission spectrum is for a particular temperature) but any photon can certainly be emitted by any black body that is higher than that typical temperature. The hotter a body is, the more it radiates at all frequencies even though the peak frequency shifts upwards as temperature increases.
The second important physical principle here is that the laws of radiation are symmetric (as indeed almost every physical law is). That is, whatever can be emitted can be absorbed. So a hot black body object can absorb at all frequencies that can be emitted by a black body of the same or lower temperature. These are the rock solid physical laws that underpin our ability to make radios, lasers, indeed any technology that can emit or receive any kind of radiation.
This means that to doubt about whether a body can absorb a ‘cooler’ photon (meaning one typically but not necessarily emitted by a body at a lower temperature) is to doubt whether our current basic understanding of physics is correct. Now by all means feel free to doubt all that, but recognise that this would be an extraordinary thing if everything we thought we knew since Maxwell were so badly wrong. It is utterly extraordinary, and there would need to be some serious discrepancies in the evidence to entertain it. For that reason, since I have never heard of the slightest scrap of such evidence, as soon as I read what Anthony’s experiment did, I knew what he would find, and indeed he did find exactly that.
We have here a really strange phenomenon: a truly fantastic claim (that our understanding of radiation is dramatically wrong) is being put forward, without any evidence, as the reason why our understanding of something derivative (namely the greenhouse effect) is mistaken. Surely it is obvious why that is so very perverse a process? It differs in no substantive way from, for example, claiming that powered flight is impossible because invisible pink unicorns block the takeoff of aircraft.
I should add here that I am not taking issue with Richard whom I have quoted, although I started out clarifying what seems to be a mistake in his physics, rather I am trying to show why this (apparently common) mistake logically leads to bizarre conclusions. The only reason I can think of why this weird idea is gaining currency is that it seems to be associated with careless, but plausible-sounding, statements of the second law of thermodynamics.
Is not the reason that manufacturers of open top light shades indicate a limit on the wattage of incandescant bulbs because back radiation from the shade causes the bulb to overheat and explode?
Greg House says:
May 27, 2013 at 9:04 pm
Of course it does! Thermodynamics is by its very nature about the behaviour of extended bodies, which makes it at its fundamental level a statistical law. An individual photon can go anywhere it is permitted to travel by the laws of optics and the quantum laws of interaction with atoms etc., so photons can certainly travel from an atom in a cold body to an atom in a warm body; but it is less likely and so the majority flow establishes a heat flow from warmer to colder. The probability of its being violated in a particular case is nonzero, but so small as to never occur to a body of even the size of a pea anywhere in the universe in its entire lifetime. Look up statistical thermodynamics if you want to learn more.
Well, after all that unnecessary word-salad almost completely unrelated to my original post, I’d like to say “boorish” thanks.
Any chance of repeating the experiment with the mirror at 6″ and 12″ etc.?
[waaaaaaayyyy off topic rant. This thread is about the experiment, not communications, not refrigeration, not storms – mod]
Gary Hladik says: that only a small part of the radiation is returned to the mirror.
I say he has no idea how much is returned neither does anyone really but with the mirror so close – 3 inches – a significant proportion is being returned.
At 3 feet there would be almost no temperature increase – inverse square law
And note at 209 degrees F and the mirror 3 inches away the increase is 11 K.
I say again – if 50% is reflected back standard calculations say the temperature should be ~411 Kelvin and not 382 Kelvin – if more than 50% it is even a bigger disparity – and that speaks volumes for what sort of effect one would expect at ambient temperatures and a reflecting distance of even 30 feet – so close to zero as to be unrecordable.
Konrad says (May 27, 2013 at 11:00 pm): “However, my empirical experiments also showed that incident LWIR has no significant effect on the cooling rate of water that is free to evaporatively cool.”
An Earth without the so-called “greenhouse effect” would necessarily be an Earth without water, or with all the water somehow locked away from the atmosphere. You’d also have to do without ozone, either by removing the oxygen, or by destroying ozone (chemically?) as fast as it forms.