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
@Arno Arrak –
The problem is that while the claimed feedback loop that results in excessive heating is so much junk. The skydragon folk are rejecting the GHG effect entirely. Simply because the AGW folk misused the theory and use a broken add on to it. By demonstrating that the feedback loop doesn’t function the way the AGW folk claim the skydragon crowd then claim that the entire theory is no good. The problem is that this is just as bad as the AGW folk embracing Greenhouse Gas and then using a failed model of feedback loops to do their predicting. Climate is a very complex system and you can not rip parts of it out and do a good job of figuring out what is going on. Just look at the mess that the AGW people are in now that they have spent 20+ years chasing down a wrong path and suppressing any other thought. The skydragon crowd are very much in danger of doing the exact same thing.
On the skydragon’s folks, [Note: I use skydragon because I don’t want to keep looking up Principia all the time to spell it. 😛 ], website they essentially challenge Anthony and Dr. Spencer by proposing this experiment. So if this experiment is so bad why in the world did they propose it and set it up this way.
The only correct way to counter experimental research is with experimental research. Pure theory is just that and pretty much pure fantasy until you have real world research backing it up. This isn’t to say that there isn’t a place for pure theory but if the theory doesn’t match what we can find there might just be a problem with the theory.
Anthony said: “I have just gotten word from the VP of an electronics company lab that they are doing this experiment as you and RGB describe, including measuring resistance.
I’ll have a detailed writeup later this week. We don’t need anyone to burn their house down to refute the slayer silliness.”
I have a feeling no matter what the results are, the slackers will likely say you did not understand, did it wrong again, something to move the goalposts again…
@ur momisugly Charles. “Let’s all try to find another, more apposite term for the complex system of: insulation, absorption, reflection, conduction, convection, condensation, flow, freeze and thaw… which comprise the Earth’s amazing temperature regulation system.”
I’ll second and third and … as “n” tends to a very large number.
The words Greenhouse, and blanket do not belong in any rational discussion of the atmosphere.
Charles Gerard Nelson says:
May 27, 2013 at 3:01 pm
The radiation physics of CO2 are so that you need a column of 70 km of air with the double concentration from 280 to 560 ppmv to increase the temperature at the surface with ~1°C.
Most solar panels are not that thick, and even pure CO2 would loss its heat to the environment faster that what is extra captured…
There is only one atmospheric constituent that effectively changes the mass of any particular part of the atmosphere. ! dihydrogen monoxide.
Charles Gerard Nelson says:
May 27, 2013 at 3:01 pm
The mirror is simply acting as an insulator, though inefficient and at a distance from the heat source.
In the case of wrapping the bulb in aluminum foil, aluminum is a better conductor for heat than glass, thus hardly act as an insulator. Still the bulb gets much hotter…
the word greenhouse itself is offensive,
Greenhouse- warm air trapped in a glass house, hotter at the top than the bottom.
earth’s atmosphere. Do i need to continue.
Help wanted & needed.
Consider two volumes of air each containing 10,000 molecules at, let’s say, 1000 m above msl on a NH equinox, ignoring lesser trace gases & rounded to nearest whole molecule:
A) a cold, smaller, denser, drier volume in the arctic with 7803 molecules of N2, 2100 of O2, 93 of Argon, three of CO2 & one of water vapor, and
B) a warm, larger, less dense, wetter volume in the tropics with 7494 molecules of N2, 2016 of O2, 87 of Argon, three of CO2 & 400 of water vapor.
Now leave all conditions, eg insolation, albedo, pressure and initial temperature, the same, but double the concentration of CO2, making each volume a little more massive:
Aa) 7801 molecules of N2, 2099 of O2, 93 of Argon, six of CO2 & one of water vapor, and
Bb) 7492 molecules of N2, 2015 of O2, 87 of Argon, six of CO2 & 400 of water vapor.
I say that the extra CO2 & its feedback effects will cause the arctic volume to warm slightly & the tropic volume to cool, if not remain the same within measurement margin of error. IMO, the tropic level of water vapor swamps out, for want of a better term, any effect from the extra CO2 molecules absorbing IR. In the arctic case, the excited CO2 molecule will jostle its neighbors, as they all huddle together to stay warm. As it were.
At the new equilibrium state, an extra H2O molecule might join the arctic mix, humidifying the chilly scene, with its own feedback effects.
What have I failed to consider?
Please state if I am right, wrong or nuts. Thanks.
The experiment is well done, except that I don’t like the introduction of an un-powered heating device (iron). I would think PSI could make a claim about convection at this point also, although it would be very weak and would only result in an improvement in setup.
In my opinion, PSI needed to be rebutted because of they defocus the true climate discussion. Their existence detracts from the seriousness of the main-stream and well considered climate disagreement. The boys at RC are likely celebrating the distraction (because of their own version of advocacy) but the net will be to those of us who point out the problems on both ends of the activist spectrum and report the reasoned result of science which seems to point toward the middle of the road rather than planet-ending doom.
… but where are the mirrors in the sky? The clouds? Yes, it’s warmer on a cloudy night in winter. On a clear night, there is obviously no mirror because it gets bitterly cold. But then, is the GHE about clouds or is it more about a few CO2 molecules acting like the Earth’s thermostat, and a few more causing disaster?
The experiment proves the point at hand, but I also think Richard Verney and Bathes made some good points upthread. People are getting a bit too upset about all this, I suspect. Think I’ll have a Cognac and a sigar, while the warmists chew their popcorn.
Very nice and simple experiment to do Anthony. And while it isn’t perfect, I don’t wish to quibble with the imperfections since it is good enough to show the effect in a valid manner.
But I do want to take issue with the word “emissivity” as used in this sentence.
“While the emissivity of a glass mirror is high . . .”
Here you used the wrong word. The correct word would be “reflectivity”. In fact a mirror surface (particularly a highly reflective wideband reflecting surface) has a very LOW value of emissivity. And it MUST have a low value of emissivity in order to be an effective reflector.
On another note towards improving the experiment for others who wish to expend effort in this area I would recommend the following minor improvements:
1. Do not use a glass (second surface) reflector. Use a highly polished first surface metallic reflector or deposited metal film reflector. This will have a bandwidth that is not reduced by the characteristics of the glass. Most glass is quite poor in the thermal infrared region (8 to 14 microns). Good low loss material for windows and lenses in the thermal IR region is typically Germanium and quite expensive.
2. If possible use a surface shaped to scatter as little of the light bulb’s energy away from the bulb as possible. This could be something like a spun aluminum reflector for photographic lighting. And it would allow you to see the bulb’s surface through a central hole in the reflecting surface while the mirror was in place. An array of small flat mirrors could be used to do the same thing but it would be a lot of effort to support them.
3. Run the experiment twice starting from the bulb surface temperature at equilibrium at room temperature and running through Time=5 times the equilibrium time to elevated temperature. Once with the mirror and once without it. This would give two nice curves that could be plotted against each other.
and mass, the mirror must be as near massless as possible.
Question for my fellow posters here: is it possible that Joe Bastardi is right, or partly right – or right for the wrong reasons? I’m asking because I don’t know.
I do find the Oregon Petition statement about the nugatory effects of CO2 most compelling, however, as previously noted, and I haven’t read anything here that changes my mind on that.
I have watched the video and my conclusions are: a) the experiment does not prove the “greenhouse effect” as presented by the IPCC (back radiation warming effect) and b) it does not refute the statement “a light bulb facing a mirror does not heat up or shine brighter from its own radiation coming back“.
To prove the points requires not only demonstrating that the temperature changes, but also that the reason for the change is back radiation and not anything else. The experiment failed to demonstrate the latter.
The explanation is very simple. A mirror put so close to an object much hotter then the air in the room reduces convective cooling of the object by air. As a result, if there is no internal source of energy, the object will be cooled by the air at a lower rate. If there is an internal source of energy, the reduced cooling by the air will lead to a higher temperature. This is what reduced convection does.
Since reduced convection has a warming effect, and there was reduced convection in the experiment, the warming effect in the experiment can not be attributed to back radiation just like that. Of course, the alleged back radiation warming effect is not refuted by this experiment either, so the experiment simply failed to demonstrate what was intended to be demonstrated.
Going to those extremes shouldn’t be necessary. There’s data available showing that CO2 was many higher in the past with:
1. no runaway greenhouse
2. deep ice ages
Isn’t that enough? You appear to be on the side of proper science but you’re splitting hairs about smoke and mirrors. It’s pointless and churlish.
rgbatduke says: “They will claim that the iron was turned on so that the mirror was really hotter than 230 F.”
Jeff Condon says: “The experiment is well done, except that I don’t like the introduction of an un-powered heating device (iron).”
I concur, they can claim you pre-heated the iron. They an also claim you changed the ambient room temperature. You should of included a room temperature thermometer.
Robert Brown,
I like the way that you summarize many of your complicated and often subtle analyses as straight forward or even trivial. Are you by any chance related to Laplace? That said your analogies are quite ingenuous, and your reasoning is impeccable, but maybe only to another Physicist.
Also, you should of let the bulb fall back down to 208 before ending the video as they will claim it was actually heating up some of that temperature rise the rest of the time on it’ own.
johnsullivan says (May 27, 2013 at 8:39 am): “… anyone can post comments on the Principia Scientific International Forum – its freely available to to those who can be bothered to sign up for a free account.”
==========================================================
John, your forum requires registration just to read. This is not OK. And it does not replaces comments below the articles. I think it is time you make comments possible.
When one wants to survive in a snow storm, does one sometimes not form a small cave like chamber in order to keep warm? Have not the Inuit people used igloos in the same manner for millenia?
How’s that work anyway?
Greg House says: May 27, 2013 at 3:56 pm
To prove the points requires not only demonstrating that the temperature changes, but also that the reason for the change is back radiation and not anything else. The experiment failed to demonstrate the latter.
——–
Perhaps you would like to comment on a setup I have developed to measure cool providing energy to hot object so hot with same power input gets hotter?
meant to give a link to current proposed setup for measuring “back radiation”
http://climateandstuff.blogspot.co.uk/2013/05/proposed-back-radiation-test-setup.html
When I was in engineering school, we called this stuff “Kitchen Physics”. The experiment was simple, and was designed to specifically test a suggested effect. Apparently, somebody’s hypothesis was falsified, and they are not happy. Now, the ball is in their court (Slayer’s) to execute an experiment that includes all their after-the-fact points, and prove their case with empirical evidence.
By the way, when has anyone suggested that the GHE in and of itself generates energy?
SImple test to see if energy is bounced by a mirror or not – take a Crookes Radiometer , shine a light on it, record the RPM with an appropriate gauge (electronic RPM gauge tools are readily available), then add a mirror so the light bounces back through the radiometer directly at the light source.
Does the radiometer speed up? I’m assuming it will, but this is an easy and quite visible test of the claim:
“Does shining a flashlight at a mirror so that all the radiation comes back to the flashlight make the flashlight shine brighter?”