Guest post by Ira Glickstein
A real greenhouse has windows. So does the Atmospheric “greenhouse effect”. They are similar in that they allow Sunlight in and restrict the outward flow of thermal energy. However, they differ in the mechanism. A real greenhouse primarily restricts heat escape by preventing convection while the “greenhouse effect” heats the Earth because “greenhouse gases” (GHG) absorb outgoing radiative energy and re-emit some of it back towards Earth.
The base graphic is from Wikipedia, with my annotations. There are two main “windows” in the Atmospheric “greenhouse effect”. The first, the Visible Light Window, on the left side of the graphic, allows visible and near-visible light from the Sun to pass through with small losses, and the second, the Longwave Window, on the right, allows the central portion of the longwave radiation band from the Earth to pass through with small losses, while absorbing and re-emitting the left and right portions.
The Visible Light Window
To understand how these Atmospheric windows work, we need to review some basics of so-called “blackbody” radiation. As indicated by the red curve in the graphic, the surface of the Sun is, in effect, at a temperature of 5525ºK (about 9500ºF), and therefore emits radiation with a wavelenth centered around 1/2μ (half a micron which is half a millionth of a meter). Solar light ranges from about 0.1μ to 3μ, covering the ultraviolet (UV), the visible, and the near-infrared (near-IR) bands. Most Sunlight is in the visible band from 0.38μ (which we see as violet) to 0.76μ (which we see as red), which is why our eyes evolved to be sensitive in that range. Sunlight is called “shortwave” radiation because it ranges from fractional microns to a few microns.
As the graphic indicates with the solid red area, about 70 to 75% of the downgoing Solar radiation gets through the Atmosphere, because much of the UV, and some of the visible and near-IR are blocked. (The graphic does not account for the portion of Sunlight that gets through the Atmosphere, and is then reflected back to Space by clouds and other high-albedo surfaces such as ice and white roofs. I will discuss and account for that later in this posting.)
My annotations represent the light that passes through the Visible Light Window as an orange ball with the designation 1/2μ, but please interpret that to include all the visible and near-visible light in the shortwave band.
The Longwave Window
As indicated by the pink, blue, and black curves in the graphic, the Earth is, in effect, at a temperature that ranges between a high of about 310ºK (about 98ºF) and a low of about 210ºK (about -82ºF). The reason for the range is that the temperature varies by season, by day or night, and by latitude. The portion of the Earth at about 310ºK radiates energy towards the Atmosphere at slightly shorter wavelengths than that at about 210ºK, but nearly all Earth-emitted radiation is between 5μ to 30μ, and is centered at about 10μ.
As the graphic indicates with the solid blue area, only 15% to 30% of the upgoing thermal radiation is transmitted through the Atmosphere, because nearly all the radiation in the left portion of the longwave band (from about 5μ to 8μ) and the right portion (from about 13μ to 30μ) is totally absorbed and scattered by GHG, primarily H2O (water vapor) and CO2 (carbon dioxide). Only the radiation near the center (from about 8μ to 13μ) gets a nearly free pass through the Atmosphere.
My annotations represent the thermal radiation from the Earth as a pink pentagon with the designation 7μ for the left-hand portion, a blue diamond 10μ for the center portion, and a dark blue hexagon 15μ for the right-hand portion, but please interpret these symbols to include all the radiation in their respective portions of the longwave band.
Sunlight Energy In = Thermal Energy Out
The graphic is an animated depiction of the Atmospheric “greenhouse effect” process.
On the left side:
(1) Sunlight streams through the Atmosphere towards the surface of the Earth.
(2) A portion of the Sunlight is reflected by clouds and other high-albedo surfaces and heads back through the Atmosphere towards Space. The remainder is absorbed by the Surface of the Earth, warming it.
(3) The reflected portion is lost to Space.
On the right side:
(1) The warmed Earth emits longwave radiation towards the Atmosphere. According to the first graphic, above, this consists of thermal energy in all bands ~7μ, ~10μ, and ~15μ.
(2) The ~10μ portion passes through the Atmosphere with litttle loss. The ~7μ portion gets absorbed, primarily by H2O, and the 15μ portion gets absorbed, primarily by CO2 and H2O. The absorbed radiation heats the H2O and CO2 molecules and, at their higher energy states, they collide with the other molecules that make up the air, mostly nitrogen (N2), oxygen (O2), ozone (O3), and argon (A) and heat them by something like conduction. The molecules in the heated air emit radiation in random directions at all bands (~7μ, ~10μ, and ~15μ). The ~10μ photons pass, nearly unimpeded, in whatever direction they happen to be emitted, some going towards Space and some towards Earth. The ~7μ and ~15μ photons go off in all directions until they run into an H2O or CO2 molecule, and repeat the absorption and re-emittance process, or until they emerge from the Atmosphere or hit the surface of the Earth.
(3) The ~10μ photons that got a free-pass from the Earth through the Atmosphere emerge and their energy is lost to Space. The ~10μ photons generated by the heating of the air emerge from the top of the Atmosphere and their energy is lost to Space, or they impact the surface of the Earth and are re-absorbed. The ~7μ and ~15μ generated by the heating of the air also emerge from the top or bottom of the Atmosphere, but there are fewer of them because they keep getting absorbed and re-emitted, each time with some transfered to the central ~10μ portion of the longwave band.
The symbols 1/2μ, 7μ, 10μ, and 15μ represent quanties of photon energy, averaged over the day and night and the seasons. Of course, Sunlight is available for only half the day and less of it falls on each square meter of surface near the poles than near the equator. Thermal radiation emitted by the Earth also varies by day and night, season, local cloud cover that blocks Sunlight, local albedo, and other factors. The graphic is designed to provide some insight into the Atmospheric “greenhouse effect”.
Conclusions
Even though estimates of climate sensitivity to doubling of CO2 are most likely way over-estimated by the official climate Team, it is a scientific truth that GHGs, mainly H2O but also CO2 and others, play an important role in warming the Earth via the Atmospheric “greenhouse effect”.
This and my previous posting in this series address ONLY the radiative exchange of energy. Other aspects that control the temperature range at the surface of the Earth are at least as important and they include convection (winds, storms, etc.) and precipitation that transfer a great deal of energy from the surface to the higher levels of the Atmosphere.
I plan to do a subsequent posting that looks into the violet and blue boxes in the above graphic and provides insight into the process the photons and molecules go through.
I am sure WUWT readers will find issues with my Atmospheric Windows description and graphics. I encourage each of you to make comments, all of which I will read, and some to which I will respond, most likely learning a great deal from you in the process. However, please consider that the main point of this posting, like the previous one in this series, is to give insight to those WUWT readers, who, like Einstein (and me :^) need a graphic visual before they understand and really accept any mathematical abstraction.
Ira – From the berkeley.edu link I posted above where I replied to you, http://wattsupwiththat.com/2011/02/28/visualizing-the-greenhouse-effect-atmospheric-windows/#comment-610932 is a short description of the difference between light waves.
Under Thermal IR it says: “Very high intensity can heat up and kill living tissues”, compare with others eg Green “Normally harmless, can cause blindness or burn tissue at high intensity”
The difference in effect is between heating up and burning re Thermal IR and Shortwave – that’s why UV, which we cannot feel either, burns the skin when it’s intense. If it was these shortwave energies heating the Earth, we’d bit a burnt crisp.
These energies are cold, so the classic physics division into light and heat to describe them.
This scam is a long time in the making, and as all cons it mixes up truth with the lies, that’s what makes a con seem plausible. It doesn’t matter how clever or not one is, if one takes on trust a vital piece of information for calculations which is wrong, it’s going to be gigo, it can’t be anything else.
I see this a lot in scientists arguing for AGW, they take on trust something very basics in real physics from mangled versions in AGWScience, because it’s not in their own field. Because it’s repeated so often and by so many it’s assumed that such are actual real science facts. That’s why the con’s been so successful, imo.
That NASA site I linked to is a prime example of the co-ordinated duplicity – the page I quoted from is from Real Science, before AGW it was known and understood and as you can see they’re still teaching it to children here, but if you look at some of their AGW slant pages you’ll not see it mentioned. One of their AGW pages shows a graphic with two earths, the first shows Solar, (Visible and near shortwave) entering and the second has Thermal IR going out. It isn’t actually a fib at that point, it’s just not the whole picture..
Oliver Ramsay says:
March 1, 2011 at 8:02 pm
” That’s my version! ”
It certainly is, and yet another attempt to misdirect in so many obvious ways,
and at so many levels.
” You didn’t show your thermal image, ” – Imagine it please..
” but, if it’s showing the greenhouse hotter than the tree adjacent, it’s because the greenhouse is hotter. ”
– Hotter than it’s surroundings dear chap, an obvious misdirect by you.
” If the greenhouse skin is polyethylene, the interior of the greenhoue will be what is seen for the greater part. If it’s glass, it will be the glass that is emitting.
On a clear day, the greenhouse will not be much hotter than adjacent objects with similar exposure to the sunshine. It will be hotter than the air outside. The other objects would be as warm but some heat was convected away. ”
I have not seen a shoal of red herrings before, well done that man.
With misdirects as well.
Congratulations Sir.
” In practice, a poly greenhouse works about as well as a glass one, in spite of the difference in IR transmission. Conduction/convection cools much faster than radiation in these circumstances. And in many others! ”
Concluding by shooting your own foot off,
was a bit of a let down however.
Thanks for the laughs.
Richard E Smith;
My apologies for the confusion. I was wondering why the sudden surrender on the igloo issue…
As for the rest of your comment insisting that the laws of thermodynamics are being broken… I’m a hardcore, in your face, let’s debate any time anywhere anybody but only the direct science not the bunny rabbit population in northern Alberta has declined one percent so that’s why there is more snow in Europe this year SKEPTIC.
And I’ve dug into this many times, my very first foray into the subject resulted in comments just like yours and Don V right after you. I was wrong. (50% of all the people who know me just sat up and said… huh what? he admitted to being wrong?)
I think one of the best layman level explanations ever is Ira’s pervious article on this site http://wattsupwiththat.com/2011/02/20/visualizing-the-greenhouse-effect-a-physical-analogy/
If you want something a little more technical, here’s my own explanation. Insulation isn’t quite the right word, and neither is delayed cooling. But it is what happens, the earth surface does warm if one considers ONLY radiative properties of CO2 and NO other effects, and the laws of thermodynamics are intact. Sorta ticked me off because I had to go looking deeper into the science…and the more I understood, the more of a skeptic I became. But skeptics need to get the basics and stop yelping about cold things being unable to warm hot things, and the laws of thermodynamics being broken. they aren’t.
http://knowledgedrift.wordpress.com/2011/02/27/co2-exactly-how-does-it-warm-the-planet/
George E. Smith says,
March 1, 2011 at 5:52 pm
I posted it for the variations of explanations… You could add yours to it.
But see my post above. How is the example of real light bulb which shows the proportion of Visible to Thermal IR at 5/95, and the real life physics from the steel industry which gives a billet of steel at temp X to have 100,000 times more IR than Visible not relevant to this? Is the Sun different?
Objects heating up give off Thermal IR way before the object reaches a degree of heat capable of producing white light, or any visible light at all. One figure I found was that the Sun’s Thermal IR was at 80%. This fits in better with the lightbulb and steel examples, makes more sense to me.
Anyway, the heat we feel on Earth coming from the Sun is Thermal IR, not Solar as Ira has it and as AGWScience teaches. Physics 101. See my post March 1, 2011 at 3:29 pm.
davidmhoffer says: March 1, 2011 at 4:34 pm
Re your artificial/real atmospheres and CO2 “well-distributed”, it isn’t any more than water vapour. CO2 is heavier than air so it would be, unless the lab cylinder is being agitated, at the bottom. CO2 will sink through the atmosphere displacing the air, because one and a half times heavier than air, unless there’s work being done to move it, wind. (Your lab cylinder example as problem with AGW, is also where AGW get their ‘Brownian’ motion from to produce the claim that CO2 is “well-mixed in the atmosphere” by “diffusion”; equal temperature requirement for Brownian doesn’t translate to real atmosphere, it’s convection which moves smells through a room, etc. Good explanation on http://en.wikipedia.org/wiki/Diffusion)
CO2 doesn’t readily rise in air because it is heavier, so CO2 is really localised; what’s produced locally will tend to stay local (plants also breathe out CO2 as well as taking it in for photosynthesis). Something like a volcanic explosion which would force CO2 up into higher altitudes and from there carried in big wind systems, say the jet stream, would move it much further from local, but, say, a factory chimney would release it into whatever local weather system was happening. If a calm day it would simply sink to the ground, or on windy days spread around locally, or on windy wet days, it would come down with the rain. Which comes from the water vapour being lighter than air rising and condensing.
I’ve never seen the raw data from the AIRS satellite survey, (I did see downloadable files but couldn’t get them to work), but their conclusion was that CO2 was not well-mixed in the atmosphere, it was lumpy, and they would have to re-think the data because the wind, local weather and other wind systems, had to be included in understanding CO2 distribution. The standard wind systems don’t cross hemispheres, there’s some mixing at the equator where they meet. http://www.earthfacts.net/weather/windmovement
My post to Ira before, before I posted to George and David, has not come up. Should I repost?
[no]
OK
If someone will provide a suitable subsidy I will conduct this simple test.
Travel to one of the poles during the winter period and place a sheet of glass, say one square metre, with a hole in the middle, say 100 square centimeters, on any flattish ice surface.
The glass is opaque to IR, the hole is not. Polar air is very low on water vapour and there is no sunshine. Thus backradiation from CO2 will pass through the hole in the glass and cause the ice below the hole to sublimate faster than the the covered ice. Knowing the time period and the mass of the missing ice we can calculate the energy provided by backradiation. Q.E.D.
George E Smith;
I read the papers on CO2 being “lumpy” quite a while ago and only skimmed them. My recollection is that what you say is pretty much correct. That said, the distribution of CO2 is still FAR more even than water vapour in the atmosphere. Convection at the equator in particular drives CO2 upward as well as water vapour. As temps cool, the holding capacity of the air drops, driving water vapour out as droplets, snow, what ever the balance of conditions dictate. I’m guessing that some of the CO2 gets scrubbed out as well with the rain/snow, but the bulk of it continues upward. Point being that there is a band below which water vapour dominates the absorption spectrums where the two overlap, and a band above which CO2 becomes significant by comparison. Insignificant to climate, but still not representated well by a lab cylinder with artificial atmosphere or two plates of what ever with CO2 between them.
I’d far rather spend time getting people to understand the fallacy of this thing called an “average” temperature, or the misleading way the IPCC calculates and presents sensitivity, but I don’t get a lot of traction on those issues. Everyone wants to fight about the laws of thermodynamics one photon at at time. Who needs warmists to debate with when there’s all these skeptics ready to take on skeptics?
davidmhoffer
…”and the more I understood, the more of a skeptic I became. But skeptics need to get the basics and stop yelping about cold things being unable to warm hot things, and the laws of thermodynamics being broken. they aren’t. “…….
Well David, you can become even more of a sceptic because cold surfaces cannot heat warmer surfaces.
Proof.
Look at blackbody spectrum of a solid at 250K (say), then look at the blackbody spectrum of the body at 350K.
Superimpose the spectra and compare.
We notice two things.
1. The higher temperature object produces short wavelengths that are absent from the lower temperature spectra.
2. Now look at any wavelength shared by both.
The higher temperature object produces much more radiation of that wavelength than the lower temperature object.
To make it even more concrete lets say colder object radiates 1000 photons of wavelength 15um.
The hotter object will radiate perhaps 1500 photons of 15um in the same time period.
All the colder object does is insulates to some extent the warmer object.
I will go further.
Lets say the warmer surface was in thermodynamic equilibrium with its surroundings if then a colder object is brought near and it has a lower temperature than the surroundings then the colder object will increase the heat loss from the warmer object.
Ricky111;
Until the first snowfall.
Oops!
Bryan;
Right, but if the cold object is warmer than the background, it will slow cooling of the warmest object. It’s all relative, as someone once observed.
Bryan,
I’ve debunked that nonsense hals a dozen times in this thread and the previous thread on a physical model and I’m one of several who did so, not to mention that if you’d read the articles themselves and understand them in detail, you could ask a question about a specific part of the process you didnt understand or didn’t agree with.
But instead you just skim through the very explanations of what the processes are, spout a thought experiment that is meaningless, and pronounce something impossible which you can falsify as simply as building an igloo and crawling in. So from now on i think I’ll respond to arm waving and pronouncements of conclusions with a strict time ought. Go sit in the igloo and cool off. Come out as soon as you are cooled off. Waiting for spring is an option.
Myrrh says:
March 2, 2011 at 2:44 am
George E. Smith says,
March 1, 2011 at 5:52 pm
I posted it for the variations of explanations… You could add yours to it.
But see my post above. How is the example of real light bulb which shows the proportion of Visible to Thermal IR at 5/95, and the real life physics from the steel industry which gives a billet of steel at temp X to have 100,000 times more IR than Visible not relevant to this? Is the Sun different?
Yes it’s a damn sight hotter!
If you’d take the trouble to look at the Stefan-Boltzmann equation you’d learn that cold surfaces like the earth emit in the IR around 10microns, your billet of steel around 2 microns, the sun around 0.5microns. The hotter something is the shorter the wavelength and the more energetic the light.
Objects heating up give off Thermal IR way before the object reaches a degree of heat capable of producing white light, or any visible light at all. One figure I found was that the Sun’s Thermal IR was at 80%. This fits in better with the lightbulb and steel examples, makes more sense to me.
You’re comparing objects at widely different temperature, and that figure for the sun is wrong.
Anyway, the heat we feel on Earth coming from the Sun is Thermal IR, not Solar as Ira has it and as AGWScience teaches. Physics 101. See my post March 1, 2011 at 3:29 pm.
The heat we ‘feel’ from the sun is about equal amounts of Vis and NIR, how much influence each has on a particular object depends on its absorbance at the particular wavelength, a black body will be heated by all wavelengths incident on it.
Check this out:
http://www.geo.utexas.edu/courses/387H/Lectures/chap2.pdf
See specifically figure 2.3 and 2.8, equation 2.16, figure 2.12 and related material.
The example is for a graybody atmosphere. Note, as this article emphasizes, the atmosphere is not a graybody Say a gas is affected by a certain percentage of the spectrum, say 50%.
From my link, a graybody atmosphere would have a flux of n + 1 = 1+1= 2^1/4
or a flux of 1.4142 that of a planet with no atmosphere.
This atmosphere blocks only half the radiation so the flux would be
1/2 from ground to space atmosphere blocks 1/2, 1/4 from atm. to space,
1/4 fromatm. to ground.
ground 1 up , gets 3/4 from sun, 1/4 from atmosphere.
So the total effect of a 1/2 atmosphere greenhouse is not half of a gray body, but
1/3, the total additional flux is (4/3)^ 0.25, not (2)^.25 as in the example at the link.
Now let the radion increase, say from the sun inreasing output. Now the gas, like CO2, which absorbs in a certain fraction of the infrared at the right tail of figure 2.3,
is now absorbing only 1/3 of the flux. Again, balancing the above diagram,
you’ll get a multiplicative effect of only (1 1/4)^0.25, not ( 1 1/3)^0.25 as in a 1/2 atmosphere model and not (2)^0.25 as in the article example.
Although the TOTAL warming has gone up, thanks to the sun, the greenhouse
multiplier has gone down- that’s what I meant by negative feedback.
Richard Smith,
You replied “No. Look at the Kiehl and Trenberth global energy flows diagram, for example. Earth receives 64wm2 (after deduction of thermals and evapotranspiration from insolation of 161 wm2) which somehow backradiation magnifies to an emission of 396wm2. This is more energy out than in.”
Well, you may be right about kiehle and Trenberth, but all I’m saying is that if you take any body in general (not just the Earth), which has a source of heat, then if you have less energy leaving than entering, then it must warm up.
The other points you have mentioned about being able to extract free energy if the GHG idea was true, I’m afraid I don’t understand. Perhaps you could explain in more detail why 1) GHG violates the laws of thermodynamics (if that is what you are saying) and 2) why this would lead to free energy.
Are the data in HITRAN observed or calculated?
The parameters in HITRAN are sometimes direct observations, but often calculated. These calculations are the result of various quantum-mechanical solutions. The goal of HITRAN is to have a theoretically self-consistent set of parameters, while at the same time attempting to maximize the accuracy. References for the source are included for the most important parameters on each line of the database.
http://www.cfa.harvard.edu/hitran/
The whole basis for the AGW argument rests on their misunderstanding of the true ‘greenhouse effect’. N2 and O2 are indeed members of ‘greenhouse gases’. ALL component gases of the atmosphere contribute to the ‘greenhouse effect’.
It is because the AGW proponents ignore that fact, that the miniscule effects of a trace gas like CO2 is blown way out of proportion and they make absurd assumptions, claims, and predictions.
For example:
http://www.realclimate.org/index.php/archives/2005/04/water-vapour-feedback-or-forcing/
Gavin Schmidt’s article here shows the complete fiction, fabrications of people completely deluded and ignorant of the basic sciences.
Gavin noted his puzzlement over Lindzen’s observation here:
“So where does the oft quoted “98%” number come from? This proves to be a little difficult to track down. Richard Lindzen quoted it from the IPCC (1990) report in a 1991 QJRMS review* as being the effect of water vapour and stratiform clouds alone, with CO2 being less than 2%. However, after some fruitless searching I cannot find anything in the report to justify that (anyone?). The calculations here (and from other investigators) do not support such a large number and I find it particularly odd that Lindzen’s estimate does not appear to allow for any overlap.”
If Gavin had even a tiny background in heat transfer, and thermal properties, he would have recognized that the 98% H2O, 2% CO2 numbers come from their relative specific heat capacities times their respective amounts in the atmosphere.
I actually think Lindzen was being generous regarding CO2 effects here. To me, the more accurate number would be
CO2 0.05%
ALL other ‘greenhouse gases 99.95%.
CO2 literally can’t absorb enough heat to do much of anything even if it doubles or triples or quadruples….
slight correction
My last sentence should read
“CO2 literally can’t absorb enough ENERGY to do much of anything even if it doubles or triples or quadruples….”
(I am so used to thinking that heat and energy are interchangeable which I do automatically in my mind, which they indeed are, but that may not be so obvious to most people who wish to understand the science.)
davidmhoffer says:
March 2, 2011 at 2:25 am
“Insulation isn’t quite the right word”
It’s the best single word that most people can understand. Go a little deeper by saying it allows sunlight to pass straight through to warm the surface during the day but slows down the escape of that warmth at night and I think that’s pretty much the whole enchilada in terms the proverbial bartender can understand.
I made up a rock & blanket analogy which I think is a good one. Take two black rocks and let them heat up in the sun during the day. At night put a blanket over one of them. In the morning remove the blanket and see which rock is the warmer one. That’s pretty much exactly how CO2 works – it allows the sun to warm things up during the day but prevents some of the warmth from escaping at night.
Go even further and explain that the rock with the blanket over it won’t eventually melt from the retained heat. As the blanketed rock gets warmer and warmer with each passing day the blanket becomes less effective at retaining the heat and before long the blanketed rock will reach a stable maximum daytime temperature.
Go even further by adding a second blanket after the stable temperature is reached. The rock will rise to an even higher stable maximum temperature but the temperature increase between no blanket and one blanket will be greater than the difference between one blanket and two blankets. Each additional blanket will have less warming effect than the previous blanket. That’s how CO2 works too. Nature gave us ten blankets to start with. Human activity (arguably) added four more blankets but our blankets aren’t nearly as effective as the blankets that were already there and each additional blanket we add in the future has less impact than the one added just previous to it.
There’s nothing hard to understand about that and any objections that it’s not a 100% accurate analogy are pretty much pedantic.
There’s no more a layman needs to know about how CO2 works to warm the planet.
The rest of the debate gets far more complicated beginning with exactly how much surface warming there will be and what associated changes might come along with it.
Addtional points that cannot be reasonably argued against are that atmospheric CO2 has been 10-20 times higher in the earth’s past, persisted that way for tens and hundreds of millions of years, and the earth was green from pole to pole during those times. There has never been a runaway greenhouse in the earth’s history. Green plants grow faster and use less water as atmospheric CO2 levels rise. Everything higher up the food chain benefits from more and larger green plants. The earth has experienced a number of runaway freezing events called ice ages. The earth has been in an ice age for the past 3 million years. Ice ages are bad for living things. The Holocene interglacial, the past 15,000 years, is a temporary respite from glaciers that bury New York City and all points north under a mile of ice. These interglacial respites last an average of 12,000 years while the glaciation side of the cycle last an average of 90,000 years. We’re overdue for the return of the ice age and should be justifiably concerned about doing things that will hasten its return. Worrying about doing things that will delay its returns is absurd. Worrying about global warming is absurd – we need all the global warming we can get.
davidmhoffer
The igloo insulates the person inside.
It is not in itself a source of heat.
It merely reduces the heat loss from the person.
Its exactly the same situation as the insulating lagging of a hot water tank.
Domenic says:
March 2, 2011 at 7:22 am
The whole basis for the AGW argument rests on their misunderstanding of the true ‘greenhouse effect’. N2 and O2 are indeed members of ‘greenhouse gases’. ALL component gases of the atmosphere contribute to the ‘greenhouse effect’.
Absolute nonsense, take a look at the figure I cited above N2 and O2 contribute many orders of magnitude below CO2 and H20. It is you who have the ‘misunderstanding’ and in the face of the evidence to the contrary it seems more than that.
Regarding the 98% number, the relative heat capacities have nothing to do with the GHE, that number is a fabrication by Lindzen.
Phil. says:
March 1, 2011 at 7:55 pm
“No, how do you propose that the atmosphere gets hotter than the surface?”
I don’t believe I ever said the atmosphere gets hotter than the surface, but if the pressure stayed the same then (PV=nRT) applies so the atmosphere would start at
0 C. Then add heated molecules that cannot radiate and over time they would get to the temperature of the surface. No conduction exists between things of the same temperature.
>>>>>Ira Glickstein, PhD says:
March 1, 2011 at 7:19 am
I googled images for “outgoing infrared spectrum” and found this: http://www.skepticalscience.com/images/infrared_spectrum.jpg
It should the spectrum looking up from somewhere in the arctic on a clear day and the view looking back down from 20 km. The incoming radiation would be the re-emitted IR from the atmosphere that you wanted. It clearly shows the 7 um, 10 um and 15 um bands Ira is talking about.
THANKS Tim Folkerts for the link. I knew some WUWT reader would be alert enough to answer Fred Souder’s good question . GREAT LINK, let me repeat it: http://www.skepticalscience.com/images/infrared_spectrum.jpg
Here it is for all to see:<<<<<
The link shows a chart of upwelling radiation at 20km looking down and downwelling radiation at the surface looking up. As I see it, the upwelling radiation is only between 9.25μ and 10μ (1080 and 1000 cm^-1 wave number). But if the N2 and O2 molecules are radiating like a dense body without absorbing any radiation, as so many seem to be claiming, wouldn't one expect to see a BB radiation between ~8μ and ~14μ (1250 cm^-1 and 715 cm^-1 wave number). This would be the open window between the H2O and CO2 absorption windows.
As that doesn't seem to be the case here, one can only conclude that the blip on the chart is due to something else unknown, but certainly not downwelling radiation from N2 and O2. The model as presented by Ira still does not reflect reality!
My gut feeling is that if N2 and O2 were indeed radiating, it would have a disastrous effect on the cooling mechanism of this planet. But that would require more looking into!
mkelly says:
March 2, 2011 at 8:29 am
Phil. says:
March 1, 2011 at 7:55 pm
“No, how do you propose that the atmosphere gets hotter than the surface?”
I don’t believe I ever said the atmosphere gets hotter than the surface,
No but you said this:
“By the way by your statement above you are in the camp that says without GHG we would be a very hot world indeed. Not at -18 C.”
So you certainly seem to think it for some reason, most likely a cold ice-covered surface with a troposphere like Triton’s.
but if the pressure stayed the same then (PV=nRT) applies so the atmosphere would start at 0 C. </em.
This is a bizarre statement with no basis in science, why do you think it should be at 0ºC, and why would PV=nRT lead to that?
Then add heated molecules that cannot radiate and over time they would get to the temperature of the surface. No conduction exists between things of the same temperature.
They’d cool with altitude just like the N2 atmosphere of Triton does, above that a stratosphere.
Laws are like pie crusts, made to be broken (paraphrasing Lenin). I am sorry, but you have misinterpreted the laws of thermodynamics, at least in the case of radiation. No laws have been broken here.
A moral, sensible, well-bred person will not insult me, and none other can. (Paraphrasing William Cowper)
Please have a look at the graphs (above in this comment thread) immediately after my comment with the following time stamp:
Please look at the second graph and notice that it is labeled “(b) Surface looking up”. Notice that the wavelengths are at the top of the graph and there is considerable radiation coming DOWN to the Earth from the Atmosphere at ~7μ, ~10μ, and -especially- ~15μ. That is what I was trying to help visualize in my graphics.
The second law of thermodynamics refers to the NET transfer of heat energy that must be from warmer to cooler bodies. But, as was noted earlier in this thread, if you are spraying me with a fire hose and I am simultaneously spraying you with a garden hose that has blue-tinted water, I will get a lot wetter, but you will get some blue water on your clothes.
The first law of thermodynamics of course prevents the Atmosphere from creating energy out of nothing. But, it is not doing that in my graphic. It is simply returning some of the ~7μ, ~10μ, and ~15μ energy that was radiated UP from the Earth to the Atmosphere in a previous time slot of the animated graphic. The energy being returned is a portion of the energy radiated UP from the Earth, after it has been absorbed and re-emitted by the GHGs in the Atmosphere. If I give you $1000 in bills and change, and you give that money to your friends and they give some money back to you and you later return $400, possibly in different denominations, to me, you have not created that money, have you?
I hope this clears things up a bit DonV.
Dave Springer;
I used to use “insulation” and it is a pretty good description. Someone determined to “not believe” almost always comes up with the same objection. If you have a warm building, but with no heat source in it (just assume it is already warm) it will cool off slower with insulation than without insulation, but wrapping the insulation around it would never make the building temperature increase.
So then we’re off on the merry go round, explaining that the insulation can let some energy in and some not out as fast, and the combination is a warmer building. And then…
I still maintain that the various explanations are splitting hairs in the end. The IPCC hollers doubling CO2 = 3.7 w/m2 = +1 degree. But the quietly forget that they are talking about +1 at the “effective black body” temp of the earth, which is -19 as opposed to the average surface temperature which is +15. They don’t even make the pretense of converting via Stefan Boltzman to what that would mean at surface, which is more like 0.6, they even go so far as to say that there may be no change at all to surface temps, but climate will change anyway. Nor is there any discussion that there is not such thing as an “average” temp in the climate sense. If we accept +1 at effective black body and then extrapolate from SB to surface at +0.6, then we need to extrapolate even more…what happens in the tropics which are at +30? about +0.2 and at the poles at -40? about + 4 (guestimates for illustrative purposes). So, if the hot days in the tropics go from 30.0 to 30.2, will anyone notice? will the polar bears in their winter dens notice that its -36 instead of -40?
My point being that there is a lot of science in IPCC AR4 that is accurate, but presented in such a way that it is completely misleading. Just getting through the effective black body discussion knocks half their argument out of existance, explains why water vapour doesn’t increase across the board as predicted, that most of the warming happens at nigh time lows, in winter, in arctic zones, and so pretty much doesn’t matter.
Give me a white board and 30 minutes to go through that and I’ll swing far more warmists to the skeptic side than days and days and days of refining co2 models down to photon by photon accuracy.
Bryan,
When you crawl into the igloo, exactly how does it reduce the heat loss from the person? Do the photons rising from the person’s skin get traffic reports telling them that there’s an igloo out there, slow down?
No, the igloo doesn’t generate any heat. But it does absorb heat from you when you crawl in. Some of that heat it passes along to the outside, and some it radiates back at you. So you are in fact being warmed by heat from a colder surface radiating toward you.