Radiative Physics Simplified II
A guest post by Jeff Id
Radiative physics of CO2 is a contentious issue at WUWT’s crowd but to someone like myself, this is not where the argument against AGW exists. I’m going to take a crack at making the issue so simple, that I can actually convince someone in blogland. This post is in reply to Tom Vonk’s recent post at WUWT which concluded that the radiative warming effect of CO2, doesn’t exist. We already know that I won’t succeed with everyone but when skeptics of extremist warming get this wrong, it undermines the credibility of their otherwise good arguments.
My statement is – CO2 does create a warming effect in the lower atmosphere.
Before that makes you scream at the monitor, I’ve not said anything about the magnitude or danger or even measurability of the effect. I only assert that the effect is real, is provable, it’s basic physics and it does exist.
From Tom Vonk’s recent post, we have this image:
Figure 1
Short wavelength light energy from the sun comes in, is absorbed, and is re-emitted at far longer wavelengths. Basic physics as determined by Planck, a very long time ago. No argument here right!
Figure 2 below has several absorption curves. On the vertical axis, 100 is high absorption. The gas curves are verified from dozens of other links and the Planck curves are verified by my calcs here. There shouldn’t be any disagreement here either – I hope.
Figure 2 – Absorption curves of various molecules in the atmosphere and Planck curve overlay.
What is nice about this plot though is that the unknown author has overlaid the Planck spectrums of both incoming and outgoing radiation on top of the absorption curves. You can see by looking at the graph (or the sun) that most of the incoming curve passes through the atmosphere with little impediment. The outgoing curve however is blocked – mostly by moisture in the air – with a little tiny sliver of CO2 (green curve) effective at absorption at about 15 micrometers wavelength (the black arrow tip on the right side is at about 15um wavelength). From this figure we can see that CO2 has almost no absorption for incoming radiation (left curve), yet absorbs some outgoing radiation (right curve). No disagreement with that either – I hope. Tom Vonk’s recent post agrees with what I’ve written here.
Energy in from the Sun equals energy out from the Earth’s perspective — at least over extended time periods and without considering the relatively small amount of energy projecting from the earth’s core. If you add CO2 to our air, this simple fact of equilibrium over extended time periods does not change.
So what causes the atmospheric warming?
Air temperature is a measure of the energy stored as kinetic velocity in the atoms and molecules of the atmosphere. It’s the movement of the air! Nothing fancy, just a lot of little tiny electrically charged balls bouncing off each other and against the various forces which hold them together.
Air temperature is an expression of the kinetic energy stored in the air. Wiki has a couple of good videos at this link.
“Warming” is an increase in that kinetic energy.
So, to prove that CO2 causes warming for those who are unconvinced so far, I attempted a thought experiment yesterday morning on Tom Vonk’s thread. Unfortunately, it didn’t gain much attention. DeWitt Payne came up with a better example anyway which he left at tAV in the comments. I’ve modified it for this post.
Figure 3- Experimental setup. A – gas can of air with all CO2 removed at ambient temp and standard pressure. B – gas can of air diluted by 50 percent CO2, also at ambient temp and standard pressure. C ultra insulated laser chamber with perfectly transparent end window and a tiny input window on the back to allow light in from the laser. Heat exit’s the single large window and cannot exit the sides of the chamber.
Figure 4 is a depiction of what happens when C contains a vacuum.
Figure 4 – Laser passes straight through the chamber unimpeded and a full 1000 Watt beam exits our perfect window.
The example in Figure 5 is filling tank C with air from tank A air (zero CO2) at the equilibrium state.
Figure 5 – Equilibrium of hypothetical system filled with zero CO2 air from canister A.
Minor absorption of the main beam causes infrared absorption and re-emission from the gas reducing the main beam from the laser. This small amount of energy is re-emitted from the gas through the end window and scattered over a full 180 degree hemisphere.
What happens when we instantly replace the no-CO2 air in chamber C with the 50% CO2 air mixture in B?
Figure 6 – Air in C is replaced instantly with gas from reservoir B
From the perspective of 15 micrometer wavelength infrared laser, the CO2 filled air is black stuff. The laser cannot penetrate it. At the moment the gas is switched, the laser beam stops penetrating and the 1000 watts (or energy per time) is added to the gas. At the moment of the switch, the gas still emits the same random energy as is shown in Figure 5 based on its ambient temperature, but the gas is now absorbing 1000 watts of laser light.
Since the beam cannot pass through, the CO2 gains vibrational energy which is then turned into translational energy and is passed back and forth between the other air molecules building greater and greater translational and vibrational velocities. —- It heats up.
As it heats, emissions from the window increase in energy according to Planck’s blackbody equation. Eventually the system reaches a new equilibrium temperature where the output from our window is exactly equal to the input from our laser – 1000 watts. Equilibrium! – (Figure 7)
Figure 7 – Equilibrium reached when gas inside chamber C heats up to a temperature sufficient to balance incoming light energy..
The delay time between the instant the air in C is switched from A type air to B air to the time when C warms to equilibrium temperature is sometimes stated as a trapping of energy in the atmosphere.
“CO2 traps part of the infrared radiation between ground and the upper part of the atmosphere”
So from a few simple concepts, two gasses at the same temp, one transparent the other black (at infrared wavelengths), we’ve demonstrated that different absorption gasses heat differently when exposed to an energy source.
How does that apply to AGW?
The difference between this result and Tom Vonk’s recent post, is that he confuses equilibrium with zero energy flow. In his examples and equations, he has a net energy flow through the system of zero, which is fine. Where he goes wrong is equating that assumption to AGW.
What we have on Earth, is a source of 15micrometer radiation (the ground) projecting energy upward through the atmosphere, exiting through a perfect window (space) – sound familiar? Incoming solar energy passes through the atmosphere so we can ignore it when considering the most basic concepts of CO2 based warming (this post), but it is also an energy flow. In our planet, the upwelling light at IR wavelengths is a unidirectional net IR energy flow (figure 2 – outgoing radiation), like the laser in the example here.
Of course adding CO2 to our atmosphere causes some of the outgoing energy to be absorbed rather than transmitted uninterrupted to space (as shown in the example), this absorption is converted into vibrational and translational modes (heating). Yes, Tom is right, these conversions go in both directions. The energy moves in and out of CO2 and other molecules, but as shown in cavity C above, the gas takes finite measurable time to warm up and reach equilibrium with space (the window), creating a warming effect in the atmosphere.
None of the statements in this post violate any of Tom’s equations; the difference between this post and his, is only in the assumption of energy flow from the Sun to Earth and from Earth back to space. His post confused equilibrium with zero flow and his conclusions were based on the assumed zero energy flow. The math and physics were fine, but his conclusion that insulating an energy flow doesn’t cause warming is non-physical and absolutely incorrect.
Oddly enough, if you’ve ever seen an infrared CO2 laser cut steel, you have seen the same effect on an extreme scale.
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So finally, as a formal skeptic of AGW extremism, NONE of this should create any alarm. Sure CO2 can cause warming (a little) but warmer air holds more moisture, which changes clouds, which will cause feedbacks to the temperature. If the feedback is low or negative (as Roy Spencer recently demonstrated), none of the IPCC predictions come true, and none of the certainly exaggerated damage occurs. The CO2 then, can be considered nothing but plant food, and we can keep our tax money and take our good sweet time building the currently non-existent cleaner energy sources the enviro’s will demand anyway. If feedback is high and positive as the models predict, then the temperature measurements have some catching up to do.
Even a slight change in the amount of measured warming would send the IPCC back to the drawing board, which is what makes true and high quality results from Anthony’s surfacestations project so critically important.
This is where the AGW discussion is unsettled.
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My thanks to Jeff for offering this guest post – Anthony
George E. Smith said:
“ONLY water (H2O) exists in the atmosphere in all three ordinary phases of matter; and it is the physical and chemical and other properties of water that totally regulate the range of temperatures on earth to the extent that even solar fluctuations get washed out by cloud modulation over the long haul.”
Thanks, George. That would support my contention that the regulatory mechanism is the speed of the hydrological cycle.
Further to my post above …
If it was as simple a transfer to kinetic energy as you imply, then why wouldn’t the atoms absorb at all wave lengths and just result in atoms with different speeds? Your explanation doesn’t explain the limits in the absorbtion bands. And if its not an energy transfer into kinetic energy but into molecular energy, does that mean the atoms actually dont increase in temperature?
My devil’s advocate position would say that the Carbon atoms would absorb all the photons they could until all the electrons occupy all the available higher orbits and then the rest would simply have to pass through.
I might add that intuitively, I think your system ought to warm, but I’m not too happy with your explanation.
@pamela:
Does it rise all by itself? YES. It’s called gas diffusion. Denser gases will only stay at the bottom of a volume for a limited time, until they diffuse.
@Jeff, nice simple explanation but …
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If feedback is high and positive as the models predict, then …
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AFAIK the models ASSUME high positive feedback, they do not predict it.
“climate sensitivity” is purely a fiddle factor to make make naive models which do not attempt to take “internal variability” into account, do what they want them to do.
The trouble is “internal variability” means things like changes in ocean currents (PDO etc.) and changes in cloud formation.
Having removed nearly all that causes climate variation , they have to scale up the real CO2 effects, predicted by real physical models, and get a very bad fit to climate data.
“climate sensitivity” is an arbitrary , fictitious fiddle factor to make the simplistic model fit the outcome they assumed before starting the model.
They then rerun the model without the fictitious man made warming and it does not fit at all. This is presented as “proof” of the initial models validity.
http://www.metoffice.gov.uk/climatechange/guide/quick/doubts.html
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When natural factors alone are considered, computer models do not reproduce the climate warming we have observed. Only when man-made greenhouse gases are included do they accurately recreate what has happened in the real world.
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this is doubly misleading since the models do not “accurately recreate” anything.
Gail Combs kindly referred us to this
Research Article: Automated Observations of the Earthshine
http://www.hindawi.com/journals/aa/2010/963650.html
“For a decade, we have been measuring the Earth’s reflectance by observing the earthshine, which is sunlight reflected from the Earth to the Moon and retroflected to the nighttime Earth. …..The earthshine observations reveal a large decadal variability in the Earth’s reflectance [7], which is yet not fully understood, but which is in line with other satellite and ground-based global radiation data…”
I would be inclined to bet that the variations in Earthshine and the consequent albedo changes will eventually be found to be directly related to the average latitudinal positions of the cloud bands of the various jet streams and the ITCZ. The variations being due to changes in the angle of incidence of solar shortwave energy as those clouds move poleward and equatorward beyond normal seasonal variability over centuries.
Roy Clark says:
August 6, 2010 at 12:47 pm
There should be no doubt that the downward LWIR flux from both CO2 and H2O in the atmosphere exchanges LWIR flux with the surface and helps keep the surface warmer than it otherwise would be….
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Roy how about an article about this with explanations that can be understood by lay people. As others have mentioned Al Gore had great influence because he kept the message simple. We need to refute him with science, but science that the majority of people can understand.
Pamela Gray says: “…While I understand that historically, whole language bec[a]me the preferred/only (and very unfortunate) method of reading instruction, it is no longer the case….“Read Naturally” [is] often touted as a computer based reading fluency intervention but is at the top of my bad list. It is a whole language holdover that needs to be entirely removed from our schools, burned till nothing is left but ashes, and the authors tarred and feathered.”
Yes, one of my pet peeves. Another tragedy is that the “look-say” method of reading instruction has been paralleled by the “think-say” practise of speech, in which every single thought of the individual is immediately expressed, whether it has any merit or not.
Jeff Id said:
“For those who are discussing convective heat transfer, of course you are right that this happens but it is related to the magnitude of the warming effect rather than whether the effect exists.”
I don’t think that’s quite right because it doesn’t clearly define ‘warming’.
If extra downward IR from more CO2 causes more (or more accurately, earlier /accelerated ) evaporation then the surrounding environment cannot warm because evaporation is a net cooling effect.
Instead the additional latent heat in the evaporated water vapour makes the body of air containing that water vapour lighter so that it rises with an increase in convection but because all the extra energy is in latent form there need be no (possibly cannot be any) discernible temperature increase.
I think that resolves a lot of confusion. There is ‘warming’ of a sort but only by way of more energy in the air in the form of latent heat in water vapour. So you do not necessarily need higher temperatures to create faster convection.
I’m glad I just thought of that because it disposes a problem I’ve had for some time with warmists who say there must be some warming from extra downward IR over water.
Clearly not so, simply because water vapour is lighter than air and more water vapour in a given volume of air will provoke faster convection (and thus a faster hydrological cycle) with no discernible warming at all.
Scott said:
“according to Roy Spencer, all of the supposed warming in recent decades can be accounted for with only a 2% change in cloud cover.”
Well I reckon you could get that from the latitudinal shift in the cloud bands that we have actually observed over the period 1970 to 1995.
Since then the cloud bands have been going back equatorward again and hey presto albedo is increasing.
http://wattsupwiththat.com/2007/10/17/earths-albedo-tells-a-interesting-story/
This climate stuff looks to me like turning out to be quite simple after all. The only thing we need to ascertain is the precise cause of those latitudinal shifts and I’ve already set out my ideas on that here and elsewhere.
donald penman says:
August 6, 2010 at 1:01 pm
So the idea that co2 does not warm the atmosphere is to be dismissed with a thought experiment,I am open to the idea that co2 does warm the atmosphere but have not seen any proof yet….
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Donald go back to Tom Vonk’s recent post and read it very carefully. A photon packet of energy is absorbed by a CO2 molecule and an electron goes from the rest to the excited state. This does not change the velocity of the molecule unless it collides with another molecule and the energy is translated into velocity. velocity = heat.
The second part is for every excited CO2 molecule that collides with another molecule and increases its velocity, there is an equal number of “high speed” molecules colliding with CO2 and bumping the electron into an excited state.
The net effect is essentially zero AT LOCAL EQUILIBRIUM.
Tom’s post: http://wattsupwiththat.com/2010/08/05/co2-heats-the-atmosphere-a-counter-view/
Gail Combs says:
August 6, 2010 at 11:53 am
A “perfectly transparent” window material is a plate of salt (NaCl) it is used in chemistry to hold the test sample in Infrared Spectrophotometers.
It was used by Woods in 1909 to show the true” greenhouse effect” found in greenhouses was from the normal glass allowing the sun’s energy (high wavelengths) to pass into the greenhouse but trapping the infrared energy (lower wavelengths) so it could not be re-radiated out. A greenhouse built with salt glass did not become warm.
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Gail, this is completely untrue. Please read the old 1909 Woods paper. The greenhouse made with salt was almost identically warm as the greenhouse made with glass. Woods showed that the way a greenhouse works is by preventing convection – nothing at all to do with blocking IR radiation. The idea that, somehow the glass ‘blocks’ the infrared emissions, and that this is the mechanism that warms greenhouses, was utterly debunked by Woods in 1909. Unfortunately, the idea that, as you put it, greenhouses work by “normal glass allowing the sun’s energy (high wavelengths) to pass into the greenhouse but trapping the infrared energy (lower wavelengths) so it could not be re-radiated out” is a complete myth. The atmospheric ‘greenhouse effect’ is not in any way like the way greenhouses get warm: if find it incredible to think that people still believe this after its debunking over 100 years ago.
I have no issue with moderate GH warming, but would like to put up another thought experiment. (This could be tested in practice.)
I have a long tube full of CO2 (looking like a telescope). It has a transparent window at one end and the other end (the closed end) is a solid black surface. The sides are well insulated so it can only receive and radiate through the window.
I launch the tube to a position above our atmosphere and point it into to the sun. This raises the temperature of the black surface at the closed end.
I have an identical tube, except that it is empty (or filled with a non-GHG). I launch this and place it alongside the first tube, pointing into the sun. The temperature of its black surface also rises.
The physics discussed on this thread suggest the closed end of the first tube will rise to a higher temperature compared to the second tube. So I use this “potential difference” to drive an engine: the closed end of the tube full of CO2 is the hot reservoir and (purely for for demonstration) the closed end of the second as the engine heat sink. Both pointing directly into the sun.
The engine would appear to violate a thermodynamic concept that we cannot expect a practical engine to operate if the sun is the ultimate heat source and heat sink.
However, the CO2 has introduced a frequency shift between the incoming radiation and the outgoing radiation. We could call this machine a “thermal diode”?
Question for the physicists: does this engine do any useful work?
Jeff has produced a good explanation of the basic physics, and my only complaint is that the diagram shows all radiation leaving via the distant end of the tube, which is not precisely what happens (it is what happens net after the tube reaches equilibrium).
However, there is the devil in the details still. People have already begun to add clouds, ocean surface, and other complications to the issue. Here are a couple of thoughts I have and if someone can add details to these I’d appreciate it.
1) Jeff’s diagram is probably based on calculations using MODTRAN. I assume MODTRAN has been validated with measurements, but maybe it has not. Undoubtedly it could be validated only in certain bands, or perhaps on average over large portions of spectrum. Does anyone know?
2) Jeff did not mention the detailed calculations which probably depend on the assumption of local thermodynamic equilibrium (LTE), a topic on Tom Vonk’s thread yesterday. LTE allows one to apply the Planck function to the distribution of radiation at any assumed temperature. However, the Planck function applies to cavity radiation, and in the case of the atmosphere there is no cavity. LTE does not strictly apply unless radiation is fully coupled to molecular states of translation, rotation, etc, and obviously this is not the case within the atmospheric window near 10um, and maybe is not the case in many other regions of the IR spectrum. Anyone know?
3) The window I mention in 2) is to some degree a thermostat. Discussion is generally limited to the impact of CO2, but water vapor dimers and trimers may have bands within the window. Thus a moistening of the atmosphere, and increasing polymerization of water vapor may have a big impact. I’ve alluded to this before in regard to El Nino. I’ve been looking for detailed info on the internet, but there is little. Anyone know of work along these lines?
Many thanks to Jeff for a nice, easy-to-understand-for-laypeople piece! The inappropriately-named GH-effect does of course exist – but so of course do a zillion other influencing factors, which collectively surely must add up to a self-regulating climate in the long term. Or else the earth would not have survived this long without melting. This layperson is more worried about corrupt governments (is there any other kind?) than anything nature can throw at us – as devastating as nature can be.
“”” Michael J. Dunn says:
August 6, 2010 at 2:37 pm
Can comment only briefly, so apologies.
Crazydung: Thanx and a Hatlo Hat Tip to Tom Vonk.
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Khunkat: I think I have to defend Jeff’s graph. Yes, if the Earth were situated at the surface of the Sun, the Sun’s radiance would outstrip Earth’s all across the spectrum…which is the result that you get when you apply the Stefan-Boltzmann equation right out of the parking lot. But the Earth is 93 million miles away, which attenuates the radiance, so that the portion of the solar spectrum in the far infrared is much lower than the right-in-our-faces Earth emission spectrum. “””
Michael; while the spectrum of the solar radiation is approximately the 5780 K (or pick your own number) that Jeff postulates; the Stefan-Boltzmann emittance of course is attenuated by the square of the ratio of sun radius to earth orbit radius to finally yield thge 1366 W/m^2 at our orbit location.
I disagree with those who want to divide this number by 4 after applying some albedo reduction to get some puny 240 W/m^2 all over the earth surface. That insolation level will never raise a desert surface temeprature to +60 deg C or even as high as +90 deg C for some black asphalt surfaces; and it is those much hotter than 288 K sureal surface temepratures that are responsible for the greatest earth cooling effect during the heat on the noonday sun.
Mother gaia does NOT wait till after sunste to start cooling her place down; she cools it 24/7 as the saying goes; in fact Mother Gaia probably invented the term 24/7 because she operates always in real time with real instantaneous vlaues and as I have said ; does NOT do statistical mathematics.
Working with average numbers instead of instantaneous values gets you on average that nothing ever happens.
It is the hottest dryest desert surfaces on earth that are cooling the planet via radiation; not the Arctic, and Antarctic wastelands that are puny radiators by comparison.
Alexander K says:
August 6, 2010 at 1:16 pm
Gail Combs says ‘don’t you believe that stuff (about a good education), Alexander.
Sorry Gail, but I meant a non-dumbed down education…
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On that we certainly agree. My Hubby’s Grandfather came over from Europe, did not speaking any English, had a 6th grade education and still read his way through the entire public library… There is Education and then there is “education”
joshv says:
August 6, 2010 at 10:44 am
The detector doesn’t see the IR photons radiated by the ground – they’re absorbed but eventually IR photons from CO2 higher up are released and make it to the detector, so yeah white will do. If you could afford a broad spectrum color camera, then you’d see the Earth mostly okay, but covered with a yellow (or whatever color it displays for 15 um) haze – and a brighter haze in humid regions where H2O emissions join in.
Back to the laser – the laser shove photons in – they don’t make it out. The laser might call it black. However, the whole gas does glow in that IR yellow and gets brighter when the laser is on. Sort of translucent/milky, except that’s due to scattering photons, not absorbing and emitting photons.
“”” kuhnkat says:
August 6, 2010 at 1:27 pm
Jeff Id,
You ignore the FACT that the incoming IR from 1-4 microns is much larger than the outgoing through the earth’s complete power range among other things. It is really hard to compute RTE’s when you ignore large segments of the flux and concentrate on one area.
The graph you show has the sun’s output scaled to under 10 -6. Even Science of doom only used a graph at 10 -6 for the sun to get it on the same graph. Naughty naughty. “””
Well I don’t think Jeff really ignored anything. 98% of the solar energy is contained between about 250 nm and 4.0 microns, with only 1% beyond each end of that range; actually less than that at the UV end But water vapor intercepts a considerable amount of that 1-4 micron incoming, in fact H2O starst at around 750-60 nm or so. CO2 on the other hand hardly kicks in to the 4 micron band and as I have said there is less than 1% of the solar energy beyond that.
But you have to take into account the inverse square law attenuation of the Sun’s st3efan-Boltzmann like emission to arrive at the 1366 W/m^2 TSI at earth’s orbit.
Gail Combs says:
August 6, 2010 at 1:14 pm
NOPE.
Absorption of IR causes an electron to go from the ground state to the excited state. VELOCITY of the molecule is what we call heat. You missed a step.
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Gail- you have it precisely backwards. It is important to be able to distinguish between heat and temperature. Please fix your idea. VELOCITY of the molecule is what we call TEMPERATURE.
Heat is something completely different and is NOT measured with a thermometer at all.
“”” Stephen Wilde says:
August 6, 2010 at 3:05 pm
George E. Smith said:
“ONLY water (H2O) exists in the atmosphere in all three ordinary phases of matter; and it is the physical and chemical and other properties of water that totally regulate the range of temperatures on earth to the extent that even solar fluctuations get washed out by cloud modulation over the long haul.”
Thanks, George. That would support my contention that the regulatory mechanism is the speed of the hydrological cycle. “””
I’m not up on your contention; and don’t know quite what you mean by “the speed of the hydrological cycle”
From my point of view it is a quasi static situation with some average amount/density and persistence of cloud cover globally. If the CO2 content of the atmosphere is raised; which would tentd to raise atmospheric temepratures and surface temepratures; that simply leads to more evaporation on a persistent basis; which leads to more clouds in order to get more precipitation and that means more clouds which swamp the effect of the CO2.
Likewise cosmic rays or volcanic dust or arosols which enhance cloud formation simply allow more cloud cover at lower temepratures, so the temperature falls.
All one has to do is do the two mental experiments I have proposed which I call the “Birdseye” experiment after the inventor of quickfrozen foods; and the “Venus Experiment which is its opposite.
In the former one simply cools the entire atmosphere and surface down to zero deg C; unless it is already colder, and then removes the remainder of the atmospheric H2O down to the last molecule, and drop them all on the surface in whatever phase was originally there.
Now Peter Humbug says he already did this on his Playstation except he apparently didn’t drop the temperature to help get rid of the water; he just excommunicated it all; and in his experiment he says he got it all back in three months. I prefer to drop the Temperature to zero but do not freeze the oceans (they don’t freeze at zero anyway).
Absent water vapor in the atmosphere, and hence no clouds, the earth albedo is vastly reduced, and the ground level insolation soars in the mother of all forcings.
Evaporation begins on a massive scale, and the earth returns to some stable state where cloud cover balances against further warming.
IN the Venus experiment we heat the atmosphere and surface to something very high maybe +60 deg C, and we install clouds from ground to say +20 km all over the earth from pole to pole; again without melting all the ice that exists.
Now the ground level insolation is virtually zero so precipitationa nd cooling will begin on a massive scale; and it will rain I am sure for 40 days and 40 nights, until eventually some sunlight will make it to the ground and start to warm the place up again till you reach some new stable temperature where cloud cover balances the situation.
I’m not aware of any Physics that would cause the condition reached fromt he Birdseye experiment to be different from that reached after the Venus experiment. In short; there can be no tipping point that leads to thermal runaway.
Now all that presupposes that earth’s orbit does not shift enough to kick in a new ice age.
Carl Sagan went to his grave having never detected so much as one single digit (bit) of scientific data evidence of some extra-terrestrial intelligence; what a waste.
I wouldn’t want to go to mine having wasted my life stepping into and out of cloud shadows, to try and find a cloud shadow that warmed me up instead of cooling me down.
And I wouldn’t grant so much as a brass razoo to any researcher to try the same study.
JeffID
Sometime chat with somebody in industry who actually uses lasers for delivering heat to materials (as for cutting shapes- maybe ask at Tap Plastics).
If you don’t remove the vaporized work material, the laser can not deliver the energy to the surface to do the desired work.
Therefore, blowers are used and the laser may be pulsed to allow vapor removal.
If this is not done, one is putting the watts into a cloud and wasting it.
Spector says:
August 6, 2010 at 1:50 pm
RE: Gail Combs says: (August 6, 2010 at 1:05 pm) “The photon absorbed and the photon emitted should be exactly the same energy value.”
That only applies if there is absolutely no change in the energy of the entity that absorbed the photon in the first place. If you get $20 and it is stolen, then you cannot spend it. If the robber only takes $10, then you might be able to spend the other $10.
In the molecular world, the robbery may take place as a collision between two molecules. Such a collision may also result in the donation of energy.
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I guess I was not clear. I thought that is what I said.
case# 1. Photon excites CO2, CO2 emits photon of same wavelength and returns to rest state.
case# 2. Photon excites CO2, CO2 collides with another molecule of air and returns to the rest state. The 2nd molecule absorbs the energy in any of a variety of ways including and increase in velocity (increase in kinetic energy) or heat.
However I was under the impression the excitation and emission energy for a specific molecule, and for a specific type of energy (rotational or what not) had to be in discrete “packets” that conform to the wavelengths shown in figure #2.
Stephen Wilde says:
August 6, 2010 at 3:35 pm
Hi Stephen. Thanks for the link…I was unaware of that information. What I really liked was the first comment on the article you linked though…the perfect question to greenhouse gas warming. 🙂
-Scott
Great post, Jeff. Just one weak point at the end: that the uncertainty over feedbacks “makes true and high quality results from Anthony’s surfacestations project so critically important”. The problem is that it is extremely hard to know where all the heat goes, so the time taken to reach equilibrium is also unknown. If e.g. there is more mixing with deep ocean than expected then the observed warming at the surface will be at a lower rate but persist much longer. To observe the actual warming with any confidence will take several times the density of metering that we have today, and fifteen or twenty years of data from them. If the alarmists are even half right, that’s time we don’t have. So, much as we distrust them, we are reduced to depending on models and basing policy on risk minimisation. Meanwhile, we do know that there was significant surface warming over the 20th century as a whole. Yes, there are several candidate explanations, but none of them can claim to be more convincing than the known rise in CO2.
Heat is measured in :
joules
calories
BTUs
ergs
watt hours
dyne meters
electron volts
newton meters
poundal feet
NOT DEGREES
Pamela Gray says: “…“Read Naturally” [is] often touted as a computer based reading fluency intervention but is at the top of my bad list. It is a whole language holdover that needs to be entirely removed from our schools, burned till nothing is left but ashes, and the authors tarred and feathered.”
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jorgekafkazar says:
August 6, 2010 at 3:24 pm
Yes, one of my pet peeves. Another tragedy is that the “look-say” method of reading instruction has been paralleled by the “think-say” practise of speech, in which every single thought of the individual is immediately expressed, whether it has any merit or not.
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I got stuck with that “look-say” method of reading. UGH I do have a very high reading speed but I can not pronounce or spell words correctly, I can not read out loud and I also have a problem connecting the idea to the spoken word in conversation. I got some phonetics from my parents at home thank goodness, otherwise I would have had a much harder time of it in school.
It also screwed me up completely with trying to learn a language. Especially when I got stuck in a “total immersion” experimental French class with no text books and no English spoken. I learn through sight not hearing so it was a complete disaster (my only F)