Guest Post By Willis Eschenbach [See two Updates at the end]
Here’s an oddity. Some very clever folks have invented a plastic film that cools surfaces by as much as 10°C. From Science magazine:
Cheap plastic film cools whatever it touches up to 10°C
Here’s the innovative part, according to the article. The tiny glass spheres act as resonators for the infrared emitted by the underlying surface. By choosing the right size spheres, the frequency of the resonators is tuned to be that of the so-called “atmospheric window”. This is the band of frequencies that is not significantly absorbed by any of the greenhouse gases. Infrared (IR) at that frequency pretty much slides right past the water vapor, the carbon dioxide, the methane, the ozone, it misses everyone and goes straight out to space.
In other words, it dodges the greenhouse effect …
Now, I’m left with some questions.
First, is it possible-to frequency-shift infrared radiation in this manner?
Next, what does the emission curve for this material look like? As an example, here’s a typical curve from MODTRAN showing the absorption of upwelling longwave radiation:
The smooth colored lines in the upper right panel show the Planck blackbody emission curves for various temperatures. The uppermost green curve is the warmest, 300 kelvin. The lowest yellow curve is 22oK. The “atmospheric window” is the area from wavenumber 750 to 1250, interrupted in the middle by the ozone absorption band just above wavenumber 1000.
As you can see, the warmer it is, the more the peak of the Planck curves (smooth colored lines) is shifted to the right. Now, with the resonator the peak radiation is supposed to be shifted by the resonators to a wavenumber of around 1000. That’s just below the ozone absorption band.
So I’m very curious about the shape of that curve. If the peak shifts towards the right it would have the characteristics of a warmer surface … can you mess with the Planck curve like that, shift the peak? Not saying it’s impossible, metamaterials have bizarre properties, I’m just out of my wheelhouse here.
Finally, what can this be used for? Well, I had a scheme a while ago for solar distillation of water. This would have been very useful to cool the condensing side of the still.
More directly it seems like it could cool buildings. A coating that could cool a large building by even one degree would translate into big savings in air conditioning. Ten degrees would be marvelous.
Anyhow, that’s what I’m calling a reverse greenhouse effect … it concentrates the radiation on the band where there is minimum atmospheric absorption by greenhouse gases.
Best to all,
w.
My Usual Request: If you comment please QUOTE THE EXACT WORDS YOU ARE DISCUSSING. That way we can all understand your subject.
[UPDATE] Thanks to a tip from the commenter Johanus, the underlying paper is here. It has what I asked for above, the actual emissivity curve in the thermal IR range. Fascinating. Here’s a preview, a graph of the temperatures throughout the day:
Now, that is a beautiful thing for a couple of reasons.
One is that I love real data. It is so much more interesting that a computer model of the same thing. Facts. Observations. If I stick to the facts I know I can’t go far wrong.
Next, look at the photonic radiative cooler. Throughout the day it is running cooler than the ambient air temperature by something on the order of 5°C … so for all the folks who said it was impossible, there’s an old Soviet joke about a Political Commissar berating someone and saying “Yes, yes, Comrade, you’ve proven that it works in practice … but it will never work in theory!” …
[UPDATE 2] After many helpful comments I’m finally understanding what’s happening. It’s not so much related to the selective emission of longwave radiation (thermal infrared). Instead, Kirchoff’s law says that frequency by frequency, emissivity equals absorptivity. So selective emission in a narrow band also means selective absorption in the same band.
The selective absorption is important because the “atmospheric window” also means that there is very little downwelling radiation in that window. Here’ MODTRAN again, showing the downwelling radiation from the viewpoint of the surface looking up:
Now, we can see that as expected, we have a lot of downwelling radiation. With the given parameters shown at the left, it’s shown at the top right as “Iout”, about 260 W/m2.
But notice … almost none of that is in the atmospheric window. The photonic material selectively absorbs mainly in that window … but there’s almost nothing in that window to absorb.
This is how they get the large temperature differences shown in the underlying papers. The material simply absorbs poorly where the incoming longwave radiation is, and absorbs well in the window where there’s little radiation.
At least that’s my current understanding …
w.
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Hmmm … Sounds like a cousin of Maxwell’s Demon. Are they limbering up to mess with the Second Law of Thermodynamics?
I think this is a cousin of neon pigments. I wonder if you could make it a paint.
Lets flotsam out in the PNW on the Next Blob and test it out.
It would have been valuable if Eschenbach had explained why it does not violate the laws of thermodynamics.
How does the material, as described, violate the laws of thermodynamics?
The energy isn’t disappearing – it is simply photonic energy being redirected out as photonic energy rather than vibrational (heat).
ticketstopper:
You are talking about the first law of thermodynamics, which concerns energy. But this invention seemingly raises issues about the 2nd law of thermodynamics, which concerns entropy.
Killer Marmot February 13, 2017 at 10:35 am
Huh? I put it up there to discuss how it works and to ask questions, not to issue explanations.
In any case, it’s been tested and it works, so obviously it doesn’t violate thermodynamical laws.
w.
@Willis
The bumblebee of coated films!
And here I thought “discussing how it works” was issuing explanations.
My point is that anyone familiar with thermodynamics is going to immediately wonder why this invention does not violate the 2nd law of thermodynamics. It’s an obvious and foreseeable question.
A journalist should attempt to identify what questions are likely to arise among the readership, and try to address them in the story.
How does reradiation of photons violate entropy?
After all, this happens in nature all the time as via fluorescence, among other phenomena.
If it works it doesn’t violate the 2nd law or the 2nd law is wrong.
I think the first is the case as the 2nd law refers to a closed system
https://en.wikipedia.org/wiki/Second_law_of_thermodynamics
Does it cool or is it just a good thermal insulator that stops the sun from heating the surface.
Acrid test. Put a sheet of this wunderfilm on a table down in the basement of a house in the dark, so no sunlight can shine on it. Then let’s see it cool the table to 10 deg. C below the basement temperature.
I’m not saying this stuff might not be a good thermal insulator.
But stopping something from getting hotter due to natural causes, is not the same as cooling something that is not being heated by natural causes.
G
It is technically neither. Heat from light is photons hitting the surface and causing atoms in the surface to vibrate – which is heat. The material absorbs the light energy then re-radiates it out as light.
It isn’t cooling so much as it is preventing the heating from starting. For materials that are already being “heated” by light, it cuts off the ongoing energy flow.
It works at night too, so it is not just an insulator.
Let’s wrap the earth with it!
Voila – no more CAGW.
“””””…… Already, the new material, when combined with a mirror like silver film, has been shown to cool whatever it sits on by as much as 10°C. …..””””””
There’s no such thing as a cheap silver film.
Silver does have very high reflectance at visible wavelengths, but there is no assurance that it does at thermal wavelengths.
And no johny come lately can just slap a cheap silver film on top of a solar panel and suddenly find extra light that decades of careful research hasn’t been able to capture to raise the conversion efficiency.
Tell them to come back when they have their inexpensive silver enhanced solar panels available for immediate installation.
G
You use gold for IR wavelengths.
Why they use it on space stuff(plus even though it’s really heavy, it spreads very thin).
george e. smith February 13, 2017 at 12:17 pm
“””””…… Already, the new material, when combined with a mirror like silver film, has been shown to cool whatever it sits on by as much as 10°C. …..””””””
There’s no such thing as a cheap silver film.
Silver does have very high reflectance at visible wavelengths, but there is no assurance that it does at thermal wavelengths.
That’s just the point George, they want something that reflects visible but not IR.
george smith writes “There’s no such thing as a cheap silver film”. If you would read the pdf, you would find that they use an Aluminized Mylar film under their Photonic radiative cooler. Aluminized mylar is basically what we call space blankets. The actual radiative cooler consists of “seven layers of HfO2 and SiO2, whose thicknesses are defined by extensive
numerical optimization (see Methods), on top of 200nm of Ag, a 20-nm-thick
Ti adhesion layer, and a 750-mm-thick, 200-mm-diameter Si wafer substrate.”
I note that the pdf is copyright 2014, so there should have been plenty of time for this to have been developed. Makes one wonder.
The Ozone absorption peak is at 9.6 microns wavelength so it is right in the middle of the so-called atmospheric window. According to Trenberth only 4% of the total surface emitted LWIR EM radiation escapes to spacen that atmospheric window.
G
george e. smith February 13, 2017 at 2:16 pm
Thanks, george. You’re right, 9.6 microns wavelength is wavenumber 1042 (wavenumber = 10000 / wavelength). As I said in the head post,
However, I’m not sure about your claim that Trenberth said only 4% escapes through that window.
This graphic from Trenberth’s 2008 puts the number at just over 10% …
w.
From a typical average surface at about 15C (288K) the atmospheric window cover about 25% of the heat, But with a typical cloud cover of 60%, only about 10% goes directly to space, Trenberth shows 40 Wm-2 out of about 390, close to 10%. But in any event, this only effects what the atmosphere absorbs. It does not effect the surface heat loss. It is about 390 Wm-2 at 15C. Some other mechanism must cause the “cooling” if any.
Richard, I think but I am by no means sure, that the other mechanism is that the higher radiation from the glass beads, cools them faster than the surrounding material so heat is conducted from the film material to the beads and from the underlying surface to the film. Without the beads the radiation would be distributed differently across the spectrum and absorbed by the near air and would therefore be radiated or conducted back into the film. With the beads the absorption by the air is very much less and heat conducted from the surface into the film is still radiated by the beads so the temperature of the surface drops until a new equilibrium is reached when conduction from the top of the film through the film to the surface material balances conduction out from the surface material. That temperature will be lower than if the film were not in place. The silver foil greatly reduces any radiation from the air (and sun) impinging on the surface material. The limit is reached when the resonance of the beads is insufficient to radiate more energy then the net flows by other mechanisms, including from the ambient air through the film to the surface to be cooled.
So it should work in the dark as well as in sunlight. Its effectiveness would be reduced if there is anything, solid, gas or liquid, nearby that absorbs the radiation at the resonant wavelength of the beads and has a radiative, conducting or convection path back to the film or the surface to be cooled. Basically, the beads, by changing the energy density distribution of the radiated energy short circuit the other energy paths through air.
Well I got the wrong 4. He says 40 w/m^2 escapes through the atmospheric window.
G
Conduction of heat from surface to gas or vice versa is slow. I thought that emission at any wavelength would be sufficient if there was convection of air. I think that strong emission at a few discrete frequencies, even if random, would give the same effect if the air above the surface was moving.
I think this could work, at a casual first glance. Frequency shifting is no big deal – any absorber that re-emits does that.
Forget greenhouse gases: this thing also needs to punch through clouds.
My physics is too rusty to get to grips with this completely, but I’d say that for now it’s one to watch.
I’ll just say that I’ll have to see this in operation to believe it.
It will never work in the AGW/CAGW crowd though. To function there you are required to be Shiftless
Just wait for the first seagull to wash up with a load of micro glass beads in its gizzard.
It seems that the principal effect is not one of shifting wavelength but of converting thermal energy into radiated energy. It is apparently used in contact with the object to be cooled.
Day-Glo paints I believe downshifts UV to visible.
Thermal energy (heat noun) is readily converted to radiated energy, and at a rate that is bounded by the Planck radiation formula, which depends only on the Temperature.
G
Sure frequency shifting is no big deal; well so long as it only shifts to longer wavelengths.
That is the whole reason why the Beer’s law thing doesn’t apply.
Beer’s law only applies to the absorption versus path length or absorbing species amount, provided the absorbed photons stay dead.
They don’t; any absorbed energy will raise the Temperature, and eventually that absorbed energy will be radiated away as thermal radiation (at a lower frequency).
So the “transmitted” portion of the energy entering an absorbing medium, DOES NOT follow any logarithmic law.
Sharp cut optical filter glasses that can attenuate by four or five orders of magnitude at quite close to the cutoff wavelength, might still transmit 75% of the incident energy; just at a different wavelength.
You really have to go out of your way to stop materials from transmitting energy.
G
Suppose someone was suffering heat prostration or heat stroke. Wrap in them in one of these blankets ASAP, every ambulance should carry a few in summertime. I’m also thinking of NASCAR drivers, some of this on the outside of their Nomex, but what would be the flammability of this material? Probably pretty nasty, but perhaps just the opposite? Intriguing.
Absorbs almost no visible light can be used to cool solar panels ? Ohh underneath the panels ?
in the article they say that in the solar application the silver layer that reflects light is removed.
And without the silver backing, he adds, the plastic film could also increase the power generation from solar cells, which operate more efficiently at lower temperatures.
At what cost? Solar panels are already cost more than they are can produce, a small increase in efficiency at big cost does not help.
the material is plastic and glass beads. At volume that is pennies per panel.
” Solar panels are already cost more than they are can produce”
How do you manage to get to that conclusion?
Steven Mosher February 13, 2017 at 8:49 am
Steve, just because the materials are cheap does not mean actual production will be.
Tiny glass beads, lots of them. They will get into the air. Workers will have to wear protective clothes.
Cogs (cost of goods sold) -the materials are often the smallest percentage, pun intended.
michael
Sure, the plastic film could increase the power generation from solar cells, but it probably wouldn’t.
The film must “suck” heat from the solar panel through conduction first, and then through convection and emission to the surrounding environment. Plastic and glass are poor conductors of heat. A regular solar panel emits heat directly via convection and emission without having to conduct its heat through an insulating blanket first. I’m not buying the glass sphere snake oil. There’s a reason why the only boast about the film by itself without the mirror is based on the weasel word “could”. Nothing but smoke and mirrors.
The reflective layer by itself is probably what accounts for the boasted 10°C of cooling. I’ll be cooler under a mirror on the beach than my mirror-less neighbour.
Steven,even a small cost, assuming it is as small as you wish, is still a problem.
Greg, I get that by adding up all the costs and determining how much electricity a cell can produce over it’s expected lifetime.
Basic math, try it some time.
PS, assuming these plastic sheets go on the top of the solar cells (They couldn’t radiate heat to space if they were on the bottom), they are going to cut down the total amount of visible light that gets to the cells. Nothing is 100% transparent.
Beyond that, if they are plastic, they are going to weather over time, which will further reduce the amount of light reaching the solar cells.
Indeed – if the material can take photons at wavelengths not presently well converted by PV gates, then it would increase efficiency of solar PV dramatically – assuming the re-radiation is in the right direction.
The concern I would have is just how durable a plastic based material can be for such an application.
I think everyone is missing the point here, they aren’t saying there is some magical transmission of energy to space that is causing cooling, they are saying because few things absorb energy at the wavelength they are radiating at there will be little local environmental heating (small e). meaning the surrounding air, structures or body of the object it is applied to, a typical heat sink would warm everything around it thus making it self and the device it is cooling less efficient the warmer it gets, this won’t.
MarkW said:
“Steven,even a small cost, assuming it is as small as you wish, is still a problem.
Greg, I get that by adding up all the costs and determining how much electricity a cell can produce over it’s expected lifetime.
Basic math, try it some time.”
OK, if you’ve actually got the necessary information and done these calculations, could you share them with us? I’ve asked time after time when people make these claims, for them to show their work, because I’d like to know if it is true or not. So, please do share you calculations and results with us.
Steve, usually when they say something like “the plastic film could also increase the power generation from solar cells” the word “could” means something like “in a perfect World where flying Unicorns fart rainbows”; but I’m sure this is different, so we’ll just jump into our hydrogen fusion powered flying car and cruise down to the local hardware store and pick up a roll next week.
It would have to be on the top. But with regard to solar cells, it might be better to make cells that convert a wider band of photon energies into electricity by creating a layer that converts out of band photons into photons that the solar cells are sensitive to.
Nice idea!
Go for it.
The current record for doing that is something like 43% conversion efficiency, according to NREL and that is with knowledgeable experts doing everything they damn well know how to achieve that result.
Nothing is left lying around for some 4-H club project to find some extra that has been missed.
And that was done irregardless of how much it might cost to make.
When you only have one KW/m^2 to work with, the only thing that matters is efficiency.
Non-imaging capture optics is much cheaper than exotic PV structures.
So knock yourself out trying to improve the efficiency.
G
Don’t need the solar panels or other “green energy” anymore. Just solve the AGW problem by putting out square miles of this stuff.
“can you mess with the Planck curve like that” A lot of the non-black bodies ‘mess’ with the Planck curve. Including the atmosphere.
The planet does this by converting high energy photons emitted by the Sun into LWIR photons emitted by the surface and clouds. It then does this again, to a lesser extent, when water vapor that is not in the ground state condenses in the atmosphere and the state energy is converted into broad band Planck spectrum emitted by the water in the clouds. We see evidence of this in the emitted spectrum, where around 15u, the attenuation in the H2O absorption bands is slightly more than 3db where it would be exactly 3db without any subsequent conversion.
Even a perfect black body will emit a spectrum which depends upon it’s temperature. This is not directly connected to the temperature of the body which emitting the radiation it receives.
You may look at what a black body means, what black body radiation means, and what Plank’s law is. When you find out all the nasty details, you may find out that:
– the atmosphere is NOT in thermal equilibrium (yeap, quite different temperatures all over the places)
– the atmosphere is NOT absorbing all incident radiation (a nasty thing is that it’s actually transparent to some)
– the emission spectrum (which is measured from satellites) is NOT the black body spectrum (really!)
I don’t think I should detail it more. The differences from the black body are so huge that ex falso, quodlibet can be applied to prove anything you would like if you assume it true for the atmosphere. For example, you can prove that CO2 is God and it’s bringing Armageddon.
If the glass beads do preferentially emit and absorb at wavelengths with a cooler “sky temperature”, then they will tend to be more like that “sky temperature”. However, it all depends on the emission/absorption spectrum of the glass beads – which isn’t obviously shown anywhere. If it’s very wide – then the effect will be small, but if it’s narrow enough to fit in the dip (and if there are no clouds) – and if you want to be cooler, then it would work.
My understanding of the process is as you described it. The flip side is that the beads have low emissivity and absorption at the wavelengths are opaque. In this case, the beads try to reach thermal equilibrium with the sky temperature in the “window” as opposed to the various GHG absorption lines are. Conversely, beads made to have high emissivity in the IR absorption wavelengths should be warmer than a black body.
FWIW, the atmosphere is “clearest” on the order of 1 to a few GHz, sky temp there is 3K, but not much heat gets radiated there.
Yes, it’s possible to shift from higher energy excitement to lower energy emission. It’s how fluorescent bulbs work. Gas discharge generates ultraviolet light which excites phosphors which emit visible light. link
If it works you could wrap patients running dangerously high temperatures in it to cool them down
shoot, I’ll wear clothing made out of it in the Texas summer if it works.
‘ “Aww, hell yes,” said the other lurking Texan.’
Ha, yes! I’m in South Florida and was thinking the same thing. Can we make a t-shirt out of this stuff? I’ll take a dozen!
And interfere with the body’s natural mechanism.
The problem is to shift the low energy IR to higher energies. When you start with UV (invisible to the eye) and shift it with phosphors, the lost photon energy (Stokes Shift Loss) is converted to waste heat.
That’s why blue pumped white LEDs are way more efficient that fluorescent tubes. The blue pump photons already contribute a part of the visible spectrum. UV photons contribute NOTHING to the visible light, so 100% of the visible light suffers from Stokes Shift loss.
G
Why not wrap your refrigerator in the stuff, then you can unplug it from the power.
G
Agreed, but do I have to put it outside for it work, if it’s inside it’s not connected to space?
I wondered about it. Could we make tinfoil hats out of it for our Democrats? Would they get better?
No such thing as the greenhouse effect.
johnmarshall February 13, 2017 at 2:07 am
Perhaps on your planet there isn’t, but on this planet there assuredly is.
w.
The Steel Greenhouse 2009-11-17
There is a lot of misinformation floating around the web about the greenhouse effect works. It is variously described as a “blanket” that keeps the Earth warm, or a “mirror” that reflects part of the heat back to Earth, or “a pane of glass” that somehow keeps energy from escaping. It is none of these things.
People Living in Glass Planets 2010-11-27
Dr. Judith Curry notes in a posting at her excellent blog Climate Etc. that there are folks out there that claim the poorly named planetary “greenhouse effect” doesn’t exist. And she is right, some folks do think that. I took a shot at explaining that the “greenhouse effect” is a…
The R. W. Wood Experiment 2013-02-06
Pushed by a commenter on another thread, I thought I’d discuss the R. W. Wood experiment, done in 1909. Many people hold that this experiment shows that CO2 absorption and/or back-radiation doesn’t exist, or at least that the poorly named “greenhouse effect” is trivially small. I say it doesn’t show…
One thing that is absolutely certain is that this planet is not a steel greenhouse.
Very often mind experiments fall on basic premise. One may reasonably consider an analogy to be analogous but due to unknowns and/or lack of understanding, it turns out not to be analogous. The problem is that we have insufficient knowledge and understanding of Earth’s atmosphere, and the interaction with the oceans.
Water, on the other hand is a very different beast to CO2 with its heat capacity, phase changes and latent heat.
Whilst I am not suggesting that the GHE necessarily offends the laws of thermodynamics, as Einstein observed:
There are multiple lines of evidence that suggest that in the Northern Hemisphere, the temperatures today are no warmer than they were in the 1940s, notwithstanding that some 95% of all manmade CO2 emissions have occurred since 1940. If that is so, then perhaps CO2 is not the GHG that it is claimed to be, or perhaps the GHE does not operate as it is claimed to operate.
We have no good data on the Southern Hemisphere (too sparsely sampled) and since we have no data on the Southern Henisphere, we have no global data worth a pinch of salt. The only worthwhile data is that of the Northern Hemisphere and that is why I cite that as an example.
Until we know and understand absolutely everything, everything is up for grabs including the GHE as postulated by the enhanced GHE theory which has given rise to (c)AGW. I would not limit anything from debate. A closed mind does not assist understanding. It is a dangerous tool in the box.
Willis Eschenbach February 13, 2017 at 10:33 am
richard verney February 13, 2017 at 2:01 pm
One thing that is absolutely certain is that NOBODY ever said that this planet is a steel greenhouse. That is just your sick fantasy.
And of course, what such a claim does is that it allows you to impugn an argument without actually engaging with it.
I’ve shown quite clearly the basic principle upon which the “greenhouse effect” is based. I’ve shown that it works even if the atmosphere is replaced by a steel shell. This provides a deeper understanding of the effect, by removing extraneous questions of which gases and absorptivity and the like.
And because you can find nothing wrong with the idea, you build a straw man and attack that instead.
Nice try …
w.
Willis
The irony of your response is that you do unto me the very thing that you accuse me of doing unto you. You have not quoted any comment of mine that you join issue with, still less sought to explain why you join issue.
I consider that you have misconstrued my comment. I did not make any observation on whether your article was correct or not, I merely made a general comment,a caveat that should always be placed on all thought experiments. Your article being, as in the second paragraph making clear:
At the heart of any thought experiment is the projection of assumptions that underpin and upon which the thought experiment is made. Hopefully, those assumptions are based upon the best state of our knowledge and understanding at the time when the thought experiment is made.
However, over time our knowledge and/or understanding may change, and if so, it may be the case that the thought experiment becomes inapposite since it is not describing the real world as we later know and/or understand it to be,
It’s unfortunately named, but it does exist, CO2 and water vapor does scatter LWIR, Long Wave InfraRed light radiated from the Earth’s surface and results in the Earth being warmer than it would be without the scattering; this is settled science. What is poorly understood is how much of the warming is natural and how much is anthropogenic, how much more warming additional CO2 would cause, and what negative (cooling) forcings will occur and by how much.
It’s very much a matter of “Past Performance Does Not Guarantee Future Results” as the investment community would say.
Off piste but thought you could all do with a laugh-
https://www.iceagenow.info/green-energy-causing-serious-power-shortages-across-europe/
https://www.iceagenow.info/green-wind-power-nightmare/
Maybe renewables worked and that’s why the winter is so cold in Europe-
hallallulia – Im a believer.
Good simple thing.
Does not absorb visible and radiates IR. Very useful to cool down smth. Important that it is cheap.
Does not have to “shift” anything.
Just plant trees-
“The extent of the effect varies in space and in time, which complicates the issue, but large parks or tracts of urban trees can cool daytime summer air temperatures by about 10°F”
Yes, and if you live out in the country, be sure to plant deciduous for shade in the summer and coniferous for wind break in the winter. Properly sited trees can have an enormous effect on energy usage year round.
yes its known as negative UHI
A mirror like film would cool, or prevent much heat from reaching what ever it covered anyway. What it reflects away heats the atmosphere. This new stuff seems to/must reflect as well, with its silver film/surface but also absorb heat from what it is in contact with. It turns any heat it picks up into an emission that will not heat the atmosphere. Even a silver or white surface will reach ‘too hot to touch’ temps, just touch a stainless steel surface that’s been in the hot sun for a while. So I think I get it – ten degrees Celsius lower temps on things in the sun AND the reflected heat goes on a space mission. Frequency shifting is common technology now. I used to work on ruby lasers, 80’s, basically ruby crystals in a highly reflective chamber, water cooled, with high wattage light bulbs. A high fraction of the light, of a wide range of frequencies, from the bulbs, was absorbed by the ruby and re-emitted out of the end of the ruby into a light channel and directed, as a laser beam, onto thin film resistors, to cut until resistor value came into tolerance required.
I’m not sure we want to cool the planet – some warmer will be suggesting we have roads and fields, roofs and mountains covered in this stuff to stop CAGW.
I’m hopeful that warmth and extra CO2 will soon be welcomed, especially when the powers that be realise there is nothing they can do to stop it.
I think you’ve got the right take on it. The film absorbs heat by contact with its substrate, then in turn warms up the glass spheres that emit preferentially in a band that has a clear shot to outer space. Wavelength absorption and frequency shifting by the spheres don’t come into play.
The silver film is essential in sunlight. But the glass bead thing would probably still work OK in darkness without the silver.
What would it do in winter when we want to keep building warm?
Probably can’t use it on buildings in areas will cooler seasons. It seems most practical for areas near deserts or near the equator where it rarely gets cold.
…like Houston, Texas? It is/use to be considered the most air conditioned city in the world.
Here’s the innovative part, according to the article. The tiny glass spheres act as resonators for the infrared emitted by the underlying surface.
So it’s an IR laser?
Could this how glassy volcanic aerosols cool earth’s climate?
Lasers are coherent light. All these beads vibrating independently would not create a coherent beam.
The glassy stuff doesn’t stay in the atmosphere long enough to make a difference. Beyond that, they would only have this effect if the glassy beads were of the correct size.
ptolemy2,
“So it’s an IR laser?
Could this how glassy volcanic aerosols cool earth’s climate?”
There is something about clear spherical objects I’ve asked about a few time around here, that involves reflectance of light . I “discovered” some years ago that tiny glass beads are added to the line paint on roads, which causes it to preferentially reflect light right back toward the source (headlights in this case).
My interest in the beads was to use them in conjunction regular liquid plastic coating, for creating a durable clear non-skid surface for the flooring of the small wooden boat I was designing (worked perfectly), but it occurred to me when pondering this global warming stuff that water vapor particles that were tiny, would (owing to the dominance of surface tension at that scale) be spherical.
Hence, tiny water droplets would (I highly suspect) also tend to preferentially reflect light directly back at the source . . and this effect might play a role in either or both; the slowing of nighttime cooling, and possibly some small variation in global temps due to solar cycles, owing to variation in cosmic rays reaching the atmosphere, which effect small water droplet formation, as I understand it.
It’s not a laser effect, but is a sort of synchronized directional light emission effect I’m imagining . . and I’m pondering how it might play a role in this film’s (apparently) unusual properties . .
And here’s a likely “picture” of it in action.
https://micro6500blog.wordpress.com/wp-admin/upload.php?item=191
Thanks micro, but it wants a password . .
In a word, no. There is no process to mess with the Plank Curve, shifting it around.
BUT: That is not what is going on here. This is spectral absorption and emission. So you can absorb and emit at certain frequencies characteristic of the molecule. The question now becomes:
Can you absorb energy at one frequency, then emit that energy at a higher frequency (energy)?
Again, no
For people not familiar with spectra outside the Plank Curve, here is a link to the IR spectrum of methane. Not because it is a GHG, just a random example of an organic molecule with an unremarkable spectra.
http://webbook.nist.gov/cgi/cbook.cgi?ID=C74828&Type=IR-SPEC&Index=1
(scroll down)
Note that it is utterly different from the Plank Curve.
Note:
commieBob says yes, above. He is right for the question he answers, which is about spectral absorption and emission, with the emission at a *longer* wavelength (lower energy) than the absorption.
The problem here is shifting around the Plank Curve which is a completely different animal. Also, we have the case where we need to absorb at a longer wavelength (lower energy) and emit at a shorter wavelength (higher energy). There is no way to do that at all. (Outside of a 2-photon process which is terribly inefficient, vis. RAMAN spectroscopy.)
What about the fact that it is absorbing heat energy, I presume, from what it is in contact with. Wouldn’t this make more energy available for the higher energy wavelength? Also, there could be the evaporative cooling principle, analogue, going on somehow – as in a few water molecules at the surface receive K.E. from other molecules hitting it just right, they lose energy, the one gains most and has enough energy to leave the surface and evaporate. Ave speed of air molecule 500m/s, some, just a few, have, at any one time, a velocity as much as 10,000m/s! A similar principle could be going on here, where electromagnetic wave emission occurs at higher frequency when two or more lower frequency w/ls give up their energy.
One thing to look at is the Top MODTRAN graph Willis posted. The uppermost Green line for 300K corresponds to about room temperature. You can see that the peak emission is at 600/cm, and falls to about 30% of peak at 1250/cm. That, in short, is what this system has to work with at room temp. The authors claim they radiate at 10 microns, or 1000/cm. So anything below that level (in 1/cm) will not play a part. So they are only working with the right hand corner of that plot. They say they use 8 micron beads acting as resonators, so that would be 1250/cm. That means they absorb at 1250 and emit at 1000. (Maxwell’s Demon goes back to his corner.)
The whole thing looks like it would be more efficient at higher temperatures like 50C or 100C, where the peak of the Plank Curve is shifted to higher wavenumbers. This would provide more source IR at 1250 for the system to work with.
But that is an unremarkable outcome because hot things lose heat more rapidly than warm things anyway.
“where electromagnetic wave emission occurs at higher frequency when two or more lower frequency w/ls give up their energy.”
No! That is a two photon process, which is ungerate, or forbidden.
If you have a material, which can absorb 90% at wave length smaller than say, 1 micron, and absorb only 10% at longer wave length, this material will heat up in sunlight and can not emit the heat as good as receiving it. This is used for wave length sensitive receivers. So if this material is at night without incoming light in the short wave length, but has a certain temperature it can emit energy proportional to the Plank Curve with 90% in the short and 10% in the long wave length region. If you now radiate heat of long wave length on this surface, it will absorb 10% of it and heat up. But most of the emission will be in the short wave length. There is no transformation of photon with long to photon with short wave length, but only energy exchange between the body of the material to the environment via radiation. This has nothing to do with a 2-photon process.
Suppose now, the absorption characteristic is just opposite to the one mentioned above.
Good absorption and emission at longer wave length and bad at short wave length. This material can emit heat better than absorb the incoming energy from the sun, which is mostly in the short wave length. These materials have long been used for coatings of radiators. They look white, but radiate very good in the IR. It’s name is ZnO.
Mother nature has made such materials long time ago. Every leave from a potato plant cools down in night more than the surrounding air. By this the surface is colder than the air and water vapor condenses on it.
Sounds like the sort of product that would keep finding new uses.
There is no such thing as a greenhouse effect in the atmosphere. So-called “greenhouse gases” cannot trap heat and they cannot transfer heat from a cold atmosphere to a warmer earth. To believe otherwise is to believe in fake physics. What is happening here (if it works) is radiative heat transfer from a hot surface to space. To call it a “reverse greenhouse effect” is just dumb and is pandering to alarmism.
What greenhouse gases do is slow down loss of heat from the earth. The 2nd Law only puts a requirement on the direction of net flow. The surface loses heat less when it is facing greenhouse gases than it does when facing deep space through a GHG-free atmosphere. Slowing heat loss from the surface (which is outgoing IR minus downwelling IR) makes the surface warmer than it would otherwise be.
Molecules in the air absorb radiation and emit it in every direction without knowing if there is a hotter body in the direction they emit half of the energy. They effectively reflect half of the energy, which comes from the surface of the earth back to it. Certainly they are colder than the surface temperature of the earth, but the energy loss of the earth is lowered down, and so more energy stays here, heating up the mean temperature of the atmosphere. This effect is named “Greenhouse effect”. It has nothing to do with a real greenhouse. There is no glass window, but molecules which reflect radiation back to earth. This is real physics. You have not to believe, but can prove it yourself.
You can make a simple experiment yourself. Put your hands in ice water and take them out, when they are cold enough. With a thermometer you will measure a temperature lower than the temperature of your face. Now hold your hands very close, but without touching, in front of your face. You will certainly feel a warmth, because the surface of the hands reflect part of the emitted radiation from the face back to your face. So the skin can not cool down as fast as it would without holding the hands in front of the face. This is very similar to the earth’ reduced energy loss by reflecting radiation back from some matter above it.
The CO2 molecules that have absorbed IR photons don’t always lose that energy by radiative emission. Mostly they lose it by kinetic collision with other molecules. The ratio between these two forms of energy loss can be described by the mean time it takes to re-radiate an absorbed quanta versus the mean time it takes to collide with another molecule. But the mean time to collision in the zone where CO2 is absorbing IR in the atmosphere is far shorter than the mean time to re-emission. Which just means that most of the energy collected by CO2 becomes kinetic energy of the other molecules around it [heat]. [this process is not the full AGW theory because it alone wouldn’t account for the claimed temperature rise. For that some sort of amplification is tacked on].
Phillip,
If what you say were true, then the climate debate would have been over long ago in favour of us climate sceptics.
Experiments with radiating/absorbing gases such as water vapour and CO2 show that your assertion is simply not correct. Furthermore, empirical laboratory conclusions conform exactly with standard thermodynamic theory.
Assuming steady state energy flow, any gases (e.g. atmospheric water vapour and CO2) that absorb radiation from a warmer source (e.g. the earth’s surface) and emit radiation to a cooler sink (e.g. space), will cause the intermediate radiative/absorptive gases (and also, by thermal equilibration, any non-radiative/absorptive gases) to have a higher temperature than otherwise.
Strong evidence: The earth’s lower atmosphere has an empirically measured near-ground mean temperature of around 288K (15C). The Moon, at the same average distance from the Sun as the Earth, has a measured mean surface temperature of around 200K (-73C).
The battle you should be fighting is the one that most climate sceptics nowadays pursue – to point out that the additional warming effect due to man-made CO2 is negligible. This is clearly evidenced by the data, namely a rise in lower atmospheric temperatures of under 1C per century, with no significant environmental consequences, despite the best (and increasingly desperate) efforts of climate alarmists to argue otherwise.
Hey, Willis, who makes this stuff, Elon Musk?
bubblewrap on windows keeps heat IN rather well in winter, and keeps cool air IN in summer.
simply spray water from a mister to make it tick OR bluetack a few spots on edges.
you still get light in, bonus privacy;-) and saves a bit on powerbills;-)
Curtains do the same thing.
Yeah, but bubblewrap!
It’s so much more cool!
I call BS on this article because it claims to work by “pulling” heat from the surfaces it touches:
Imagine what these surface molecules experience when the plastic film draws near. (Let’s assume it’s daytime in a very hot climate, T=35C). So they’re all just minding their own business and emitting long-wave IR (because it’s hot, remember?). Suddenly, they feel this giant suction force, from above, trying to suck the heat out of them. But resistance is futile, they finally give up and start emitting long-wave IR (because it’s hot).
Wait a minute, they were already emitting long-wave IR (because it’s hot), at the “earthshine” wavelengths (~10u), in accordance with the laws of physics. So what did the film do? (besides get slightly warmer from absorbing all those photons and rebroadcast them isotropically).
So, is the film acting like a “Planck Amplifier”, remotely signalling the surface molecules to release more heat? But there is no such thing.
Pure BS.
😐
Totally agree. Absolute BS. I’m too busy laughing about it to come up with a list that shows this is wrong and unworkable. Effin ‘resonating glass balls’. Give me a break.
There seems to be another Alex on this thread. I’m the original that goes back about 10 years here
It’s not as simple as a fairy tale.
Different bodies have different emissivity in IR and they might not be ‘black bodies’. As a curiosity, a sheet of a shiny metal can become hotter when exposed to the Sun than the same sheet painted… black (to not be confused with the already mentioned ‘black body’, though). The secret is in the IR emissivity, despite the painted black one having a visible (sic) disadvantage in the visible spectrum.
The ‘heat sucking’ is indeed hilarious, though.
BZ – this ME agrees that it is BS.
Converts thermal energy to radiative energy… but only radiates outwards.
Where’s the back-radiation 😉
No BS at all, it’s simply emissive cooling, the exact same property that makes deserts cool down rapidly at night.
This might help explain what is going on.
https://en.wikipedia.org/wiki/Stokes_shift
The unfortunate use of “greenhouse effect” label should be discouraged.
It doesn’t work for real greenhouses (or glasshouses).
The ‘atmospheric’ greenhouse effect likewise is too small to be measured.
Sure CO2 absorbs around 15um and this energy is partially lost to neighbouring molecules by collision and less by re-emission .
These other molecules include H2O which numerically swamp CO2 and also have preferential emission at lower excitation wavelengths.
Then any overall local heating is swept away by convection which is a much more efficient heat transfer mechanism.
So the ‘atmospheric’ greenhouse effect is too small to be measured.
The fact that about 1% of the outgoing radiation is absorbed by water vapor and CO2 molecules is enough to heat up this zone in the atmosphere. If this energy is partly radiated back to the earth, the heat loss of the earth will be smaller and it will heat up a little. The radiation laws say, that the emitted energy is proportional to the fourth power of the absolute temperature. So if the earth has to emit 101% of the formerly emitted energy, the temperature has to rise about 0,25% of 288K. That is 0.72 degrees. This effect has been measured. If CO2-concentration will rise further, it is very likely, that more radiation will be absorbed and emitted back to the earth. What will happen, if 5% comes back and shall be emitted to the outer space? The temperature will go up 1,22% of 288K, that is 3,5 degrees. If you are young enough you will probably fell this climate change before you die. Your children and grandchildren will ask you, why you didn’t act?
Because of this:
http://www.akdart.com/images/Eldaricax.jpg
I want my grandchildren to be able to have enough food to eat. More CO2 means more food for them.
Would you like your children and grandchildren to starve to death?
Bad, bad grandpa.
“The temperature will go up 1,22% of 288K, that is 3,5 degrees.”
No, it could go up, if there were no other changes. But, there are always countervailing reactions which tend to oppose a shift in state from a given equilibrium condition. Always.
“Your children and grandchildren will ask you, why you didn’t act?”
They will look upon it as we look upon Lord Kelvin’s prediction that the Earth’s supply of oxygen would be exhausted in 400 years, as a naive prediction based upon faulty and incomplete knowledge. They will ask, “how did you ever fall for this?”
“So the ‘atmospheric’ greenhouse effect is too small to be measured.”
That’s why they have to constantly adjust global temperature data. Otherwise, the effect would be too small to scare anyone (other than a few snowflakes and pajama boys who are afraid of their own shadows).
” Your children and grandchildren will ask you, why you didn’t act?”
Because grandchild, we love you and are making sure there is food on the table. For me and granny and your and your brother, sisters and Mom and Dad!
Link to the abstract of original work using the much more expensive “seven-layer stack of alternating silicon dioxide (SiO2) and hafnium dioxide (HfO2). ”
http://www.nature.com/nature/journal/v515/n7528/full/nature13883.html
Looks like the theory is sound, although counter-intuitive.
Thanks, seaice, I was unable to find that.
w.
More BS, this expert in heat transfer will explain later.
No BS at all, it’s just Stephen Boltzman between a high emissivity surface and space.
1. Haven’t they just re-invented retro-reflective material – as what traffic signs are typically made of?
2.0 Maybe I missed it but they always seem to be talking about ‘radiating to the sky’ and hence being outside, So why not just paint your object white? Or if they want to radiate more, follow the example of camel-riding Arabs in the desert and wear (paint it) black?
2.1 They say ‘cooling’ But again as in 2.0, the ‘cooled’ object is simply not getting as hot by virtue of the incoming solar being reflected. Cause and effect hit the blender yet again.
3. Resonance is resonance, it is *very* frequency selective. 8u beads will resonate at half-lambda (16u wavelength or about minus 92degC, 1 lambda (plus 89degC), 1.5 lambda (plus 273degC) So you make different sized beads but you can easily see that quality control of the size is critical.
4. Every time a (heat) photon interacts with matter, you can regard it as being frequency shifted. All these interactions are basically heat to mechanical conversions, a-la Carnot. Those conversions are not 100% efficient because the exhaust of the engine can never be 0 Kelvin. Such a heatsink doesn’t exist. What happens is that the original short (ish) photon is shattered into a myriad of longer wavelength photons. Energy is conserved but not photons
5. They say their glass beads are great emitters (hence coolers) because they resonate. Haven’t they just shot down the entire theory of Global Warming. Carbon dioxide molecules (and water) are great resonators, great absorbers and hence great emitters. If their film works as the imagine it does and cools by being a great resonator, so do (extra) CO2 and water molecules in the atmosphere.
GHG molecules absorb energy just like the shredder in your office absorbs sheets of paper, reasonable quality stuff goes in and scrambled garbage comes out.
6. Not least, how long is a sheet of plastic going to last exposed to the sun, especially clear plastic. Plastic can only be protected (to a limited extent) from UV damage by making it opaque.
So just like Global Warming Theory, these guys have utterly utterly bamboozled themselves.
Hopefully you’re thinking about my point 3.
Those 8u beads will resonate at 16u (-89’C), 8u (+92’C), 5.33 (273’C), 4u (+451’C) etc
From here: http://www.calctool.org/CALC/phys/p_thermo/wien
“They say ‘cooling’ But again as in 2.0, the ‘cooled’ object is simply not getting as hot by virtue of the incoming solar being reflected. ”
Not according to the papers, if my understanding is correct. The material does reflect most of the incoming radiation, which prevent it heating. However the key aspect is that it also emits IR radiation because it is warm. If it is not absorbing radiation and it is emitting radiation it must be losing energy, which is cooling.
The insight must lie in the “tuning” to wavelengths in which the atmosphere is transparent.
1)Trying to think this through, if we placed an object in space it would be warmed by the sun. If we could cause all the incident energy to be reflected, then this object would not be warmed by the sun. It would emit IR black body radiation, so would cool.
2)Now we surround this object with a layer that absorbs the IR black body radiation emitted by the object. This would cause the layer to heat up. This would necessarily at least slow down the heat loss, as some of that energy would come back to the object.
3)If we can get the object to emit at wavelengths not absorbed by the layer, it will cool faster.
The above is a way of thinking about it that seems helpful to me. If you think it is in error please let me know where you think I have gone wrong.
Shame they did not provide a thermal camera view of the effect. That I would think would make the description a lot easier to decode.
I wonder why they did think of doing that?
Just noting that your Modtran display is from 70 kms up “looking down” (with no clouds). So it is showing emissions upward in a clear sky environment from the surface and from the atmosphere below 70 kms height.
The CO2 emission spectrum is at an intensity of -50C which means it is emissions from CO2 in the stratosphere (probably going to space eventually). Others are emissions from water vapor and atmospheric windows (probably also going to space).
Run it from 0 metres surface “looking up” and now you are seeing absorption of long-wave emission. Put some clouds in there too and now it is a pure blackbody curve.
Thinking abut the intuition of this. Thermodynamics says that heat will flow from the hotter to the cooler, or source to sink. For an object sitting in the atmosphere we normally think of the sink as the atmosphere in which it sits. But if we can connect the source to outer space we can “allow” heat to flow from source to sink and cool below the temperature of the atmosphere.
Energy will flow then from atmosphere to object, but I guess this process is very slow.
A good way of looking at it.
This also means it cant/wont work indoors and wont work well outside on say vertical building walls/windows where there are other nearby buildings. To maximise the effect the emission path to space should be as unimpeded as possible.