Guest post by Ira Glickstein
The Atmospheric “greenhouse effect” has been analogized to a blanket that insulates the Sun-warmed Earth and slows the rate of heat transmission, thus increasing mean temperatures above what they would be absent “greenhouse gases” (GHGs). Perhaps a better analogy would be an electric blanket that, in addition to its insulating properties, also emits thermal radiation both down and up. A real greenhouse primarily restricts heat escape by preventing convection while the “greenhouse effect” heats the Earth because GHGs absorb outgoing radiative energy and re-emit some of it back towards Earth.
Many thanks to Dave Springer and Jim Folkerts who, in comments to my previous posting Atmospheric Windows, provided links to emission graphs and a textbook “A First Course in Atmospheric Radiation” by Grant Petty, Sundog Publishing Company.
Description of graphic (from bottom to top):
Earth Surface: Warmed by shortwave (~1/2μ) radiation from the Sun, the surface emits upward radiation in the ~7μ, ~10μ, and ~15μ regions of the longwave band. This radiation approximates a smooth “blackbody” curve that peaks at the wavelength corresponding to the surface temperature.
Bottom of the Atmosphere: On its way out to Space, the radiation encounters the Atmosphere, in particular the GHGs, which absorb and re-emit radiation in the ~7μ and ~15μ regions in all directions. Most of the ~10μ radiation is allowed to pass through.
The lower violet/purple curve (adapted from figure 8.1 in Petty and based on measurements from the Tropical Pacific looking UP) indicates how the bottom of the Atmosphere re-emits selected portions back down towards the surface of the Earth. The dashed line represents a “blackbody” curve characteristic of 300ºK (equivalent to 27ºC or 80ºF). Note how the ~7μ and ~15μ regions approximate that curve, while much of the ~10μ region is not re-emitted downward.
“Greenhouse Gases”: The reason for the shape of the downwelling radiation curve is clear when we look at the absorption spectra for the most important GHGs: H2O, H2O, H2O, … H2O, and CO2. (I’ve included multiple H2O’s because water vapor, particularly in the tropical latitudes, is many times more prevalent than carbon dioxide.)
Note that H2O absorbs at up to 100% in the ~7μ region. H2O also absorbs strongly in the ~15μ region, particularly above 20μ, where it reaches 100%. CO2 absorbs at up to 100% in the ~15μ region.
Neither H2O nor CO2 absorb strongly in the ~10μ region.
Since gases tend to re-emit most strongly at the same wavelength region where they absorb, the ~7μ and ~15μ are well-represented, while the ~10μ region is weaker.
Top of the Atmosphere: The upper violet/purple curve (adapted from figure 6.6 in Petty and based on satellite measurements from the Tropical Pacific looking DOWN) indicates how the top of the Atmosphere passes certain portions of radiation from the surface of the Earth out to Space and re-emits selected portions up towards Space. The dashed line represents a “blackbody” curve characteristic of 300ºK. Note that much of the ~10μ region approximates a 295ºK curve while the ~7μ region approximates a cooler 260ºK curve. The ~15μ region is more complicated. Part of it, from about 17μ and up approximates a 260ºK or 270ºK curve, but the region from about 14μ to 17μ has had quite a big bite taken out of it. Note how this bite corresponds roughly with the CO2 absorption spectrum.
What Does This All Mean in Plain Language?
Well, if a piece of blueberry pie has gone missing, and little Johnny has blueberry juice dripping from his mouth and chin, and that is pretty good circumstantial evidence of who took it.
Clearly, the GHGs in the Atmosphere are responsible. H2O has taken its toll in the ~7μ and ~15μ regions, while CO2 has taken its bite in its special part of the ~15μ region. Radiation in the ~10μ region has taken a pretty-much free pass through the Atmosphere.
The top of the Atmosphere curve is mostly due to the lapse rate, where higher levels of the Atmosphere tend to be cooler. The ~10μ region is warmer because it is a view of the surface radiation of the Earth through an almost transparent window. The ~7μ and 15μ regions are cooler because they are radiated from closer to the top of the Atmosphere. The CO2 bite portion of the curve is still cooler because CO2 tends to be better represented at higher altitudes than H2O which is more prevalent towards the bottom.
That is a good explanation, as far as it goes. However, it seems there is something else going on. The ~7μ and ~15μ radiation emitted from the bottom of the Atmosphere is absorbed by the Earth, further warming it, and the Earth, approximating a “blackbody”, re-emits them at a variety of wavelengths, including ~10μ. This additional ~10μ radiation gets a nearly free pass through the Atmosphere and heads out towards Space, which explains why it is better represented in the top of the Atmosphere curve. In addition, some of the radiation due to collisions of energized H2O and CO2 molecules with each other and the N2 (nitrogen), O2 (oxygen) and trace gases, may produce radiation in the ~10μ region which similarly makes its way out to Space without being re-absorbed.
There is less ~15μ radiation emitted from the top of the Atmosphere than entered it from the bottom because some of the ~15μ radiation is transformed into ~10μ radiation during the process of absorption and re-emission by GHGs in the atmosphere and longwave radiation absorbed and re-emitted by the surface of the Earth.
Source Material
My graphic is adapted from two curves from Petty. For clearer presentation, I smoothed them and flipped them horizontally, so wavelength would increase from left to right, as in the diagrams in my previous topics in this series. (Physical Analogy and Atmospheric Windows.)
Here they are in their original form, where the inverse of wavelength (called “wavenumber”) increases from left to right.
Source for the upper section of my graphic.
Top of the Atmosphere from Satellite Over Tropical Pacific.
[Caption from Petty: Fig. 6.6: Example of an actual infrared emission spectrum observed by the Nimbus 4 satellite over a point in the tropical Pacific Ocean. Dashed curves represent blackbody radiances at the indicated temperatures in Kelvin. (IRIS data courtesy of the Goddard EOS Distributed Active Archive Center (DAAC) and instrument team leader Dr. Rudolf A. Hanel.)]
Source for the lower section of my graphic.
Bottom of the Atmosphere from Surface of Tropical Pacific (and, lower curve, from Alaska).
[Caption from Petty: Fig. 8.1 Two examples of measured atmospheric emission spectra as seen from ground level looking up. Planck function curves corresponding to the approximate surface temperature in each case are superimposed (dashed lines). (Data courtesy of Robert Knutson, Space Science and Engineering Center, University of Wisconsin-Madison.)]
The figures originally cited by Dave Springer and Tim Folkerts are based on measurements taken in the Arctic, where there is far less water vapor in the Atmosphere.
[Fig. 8.2 from Petty] (a) Top of the Atmosphere from 20km and (b) Bottom of the Atmosphere from surface in the Arctic. Note that this is similar to the Tropical Pacific, at temperatures that are about 30ºK to 40ºK cooler. The CO2 bite is more well-defined. Also, the bite in the 9.5μ to 10μ area is more apparent. That bite is due to O2 and O3 absorption spectra.
Concluding Comments
This and my previous two postings in this series Physical Analogy and Atmospheric Windows 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 (clouds, rain, snow, etc.) that transfer a great deal of energy from the surface to the higher levels of the Atmosphere.
For those who may have missed my previous posting, here is my Sunlight Energy In = Thermal Energy Out animated graphic that depicts the Atmospheric “greenhouse effect” process in a simlified form.
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 Emissions Spectra 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 ones 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.
Brian… boy did you ever take that wrong. I agree with many things you were saying above. I also agree there is little, or even no, effect on temperature by CO2.
That diagram is of pure geometry, has nothing to due with gravity. I probably should have made the arrow tip on the green arrow on the other side pointing upward, it only labels the amount of the effect due to the curvature of the surface of the Earth.
Reset and consider that whole effect again. It is only geometric in nature.
Wayne.
I am considering night time conditions to eliminate direct solar via cloud modification as as source of radiation around 15um.
The only radiation present will be Earth surface “up” and some collision induced and a lesser quantity of spontaneous relaxation type.
Near Earth surface the 3d spherical geometrical effect on a randomly emitted photon will be very small.
Higher up it will have greater significance.
However Gravity effects the temperature more significantly and consequently the ability to emit shorter wavelengths will fall away as predicted by Stephan Boltzmann statistics.
Joel Shore says on March 26, 2011 at 6:33 am:
“First of all, a correction: As the diagram shows, the earth’s surface emits more than 324 W/m^2…It emits 390 W/m^2. (Not all of that is absorbed by the atmosphere, but 350 W/m^2 is.)”
Ok Joel, you are right “as the diagram shows” there are, as things stand 350 W/m² that have the potential to be back radiated + the energy that disappears through the window making it up to a grand total of 390 W/m².
I just happened to use one of those figures and in hindsight perhaps I should not have done because as long as that particular diagram only shows ‘how energy levels are held steady’ it is useless as a tool to show how “Global Warming” (GW) through GHGs comes about. – Such a diagram would have to be much more complicated by far. All I, like most people without hard data, can do is to speculate and pose questions. If the answers that come back are good, then fine I have learnt something useful.
Anyway Joel, I am taking on board your logic and I do learn from it. However you say in your thought experiment by instantaneously doubling CO2;
“—– that would mean the emission is occurring from colder places and would correspondingly be less. (about 4 W/m^2 less, as it turns out). Thus, the earth system would find itself emitting less the ~235 W/m^2 that it absorbs from the sun and as a result, energy would start to accumulate, causing the system to warm. ——“
Are you sure about that one Joel? – I would have thought that as you go higher up into the atmosphere each square meter will radiate less energy – yes, true enough but there will be a lot more of them (meters²). – That’s just how “Adiabatic Cooling and warming” works; as the area the air-molecules occupy increases they lose their heat proportionately. Air just has to sink back down towards the surface again, and the heat comes back in step with its shrinking territory.
And the curious thing on that score is that if the air has got rid of some heat through loss of H2O on its way up and thus has dried out a bit it will warm to a higher temperature than it was to begin with. Well, it is not curious at all as I suppose anything that loses its lubricant will increase its internal friction.
Brian, first, I’m not very good in arguments. I even made my comment to you above without even looking at my own diagram. Brother! The little green vector was already pointed upward. I prefer to inject information only if I see it has some relevance to the discussion. I started following your comments when you agreed with me on Hans initial comment. His view, though rather unconventional, seemed totally correct also.
Lets take Fig. 8.2 from Petty in the post. The spectrums that have been tossed back and forth are misinterpreted to me anyway, both upwards from the surface and downwards from the tropopause, not necessary by you but by many. The window portion is peering deeply in both spectrums, downward can see the surface originated radiation and upward, space, very little emission there. But the rest of the spectrum is only seeing very shallow, in both directions.
I like to exaggerate when roughly analyzing something just to see if it pass the logical test. If there were no CO2 in our atmosphere, the spectrum looking upward in the range of 14 to 16 µm would look just like the portion in the range 18 to 20 µm and the surface would be warmer, not cooler. You would be seeing H2O lines in this range. But the spectrum is only “seeing” the bottom few hundreds of meters.
In the case of looking downward the bite at 14 to 16 µm would not be there at all and the upper atmosphere would be cooler, not warmer. But here is where IPCC’s incorrect assumption and my diagram and “back radiation” comes into play. IPCC assumes that a warmer upper atmosphere can somehow warm by radiation the surface. Not so, because of that little green arrow in my diagram. Small but relevant.
I guess what I am saying is that any greenhouse gas, being an infrared active gas, merely acts as a fast conduction of energy, due to its long free path length of many meters, always getting even better with altitude due to the increase in the free path length. IPCC has everything exactly backwards.
So, by that view, an increase in CO2 will have very, very little effect if any at all at the surface. IPCC is wrong and at least one of the factors is that we do not live on an infinite flat plane and that tiny upward component does matter, greatly.
I’ll step back out of the discussion here but just thought you might think a bit on that. Might help as you analyze it.
(PS: Your great at interacting here, keep it up, guess I’m asking for some help if you can see deep enough into my viewpoint)
wayne says:
March 27, 2011 at 1:59 pm
Lets take Fig. 8.2 from Petty in the post. The spectrums that have been tossed back and forth are misinterpreted to me anyway, both upwards from the surface and downwards from the tropopause, not necessary by you but by many. The window portion is peering deeply in both spectrums, downward can see the surface originated radiation and upward, space, very little emission there. But the rest of the spectrum is only seeing very shallow, in both directions.
I like to exaggerate when roughly analyzing something just to see if it pass the logical test. If there were no CO2 in our atmosphere, the spectrum looking upward in the range of 14 to 16 µm would look just like the portion in the range 18 to 20 µm and the surface would be warmer, not cooler. You would be seeing H2O lines in this range. But the spectrum is only “seeing” the bottom few hundreds of meters.
If there were no CO2 then ~15 W/m^2 sr (~90×160) less radiance would reach the surface which would make it cooler.
In the case of looking downward the bite at 14 to 16 µm would not be there at all and the upper atmosphere would be cooler, not warmer.
An additional ~(90-50)*125= 5W/m^2 sr would be leaving the surface for space and the surface would be cooler.
Of course that assumes no feedback.
O H Dahlsveen says:
You are very confused about the reason why adiabatic cooling happens. It has nothing (or almost nothing) to do with the increase in area. It has to do with the expansion of air due to the decrease in air pressure (because the air pressure is due, essentially, to the weight of the air above), not because the surface area is increasing.
And, in particular, when I say that the outgoing radiation will decrease by ~4 W/m^2, you seem to think this will be compensated by there being a lot more m^2 , so let’s do the calculation. Basically, the 4 W/m^2 corresponds (via the Stefan-Boltzmann Equation) to a change in the temperature of the radiating level by 1 deg C. A typical wet lapse rate in the atmosphere is 5 deg C per km and a dry one is 9.8 deg C per km. So, even if we use the wet lapse rate, we find it corresponds to a change in height of the effective radiating level by ~200m (and half that if we use the dry one). Now, given the radius of the earth (~6400 km), this means an increase in distance from the earth’s center of ~0.003%, which means the surface area of the sphere of the new radius is ~0.006% larger than a sphere of the old radius. Since a 4 W/m^2 change corresponds to a change of close to ~1.7%, I think we can safely ignore the 0.006% change in emitting area! You are talking about a correction that is down by something like 2 to 3 orders of magnitude!
“””Phil. says:
March 27, 2011 at 4:51 pm
If there were no CO2 then ~15 W/m^2 sr (~90×160) less radiance would reach the surface which would make it cooler.”””
Without water vapor having a continuum over those same frequencies, the atmosphere staying black to those frequencies, thermalization, and equipartition you would probably be right. To me it doesn’t matter which species of molecule absorbs radiation from the ground, only that it is absorbed or not and, of course, the spectrum would look different. Little change in temperature there. But lacking carbon dioxide, which is a great long-reaching conductor, the surface would show some slight warming, but there could be some effects that cancel that warming but I can’t find them. At the TOA, the same effect applies but closer to the tropopause and once again by water vapor in those same frequencies. I can see some inter-layer differences in temperatures though tiny without CO2 due to changes in the free path lengths in carbon dioxide’s frequencies.
wayne says:
March 27, 2011 at 7:32 pm
“””Phil. says:
March 27, 2011 at 4:51 pm
If there were no CO2 then ~15 W/m^2 sr (~90×160) less radiance would reach the surface which would make it cooler.”””
Without water vapor having a continuum over those same frequencies,
It doesn’t so no problem there.
the atmosphere staying black to those frequencies, thermalization, and equipartition you would probably be right.
Well no absorption so none of those will occur, so the integral of the ‘bite’, ~15W/m^2 sr will be lost to space instead of reaching the surface.
wayne
Thanks for your comments.
Have you read this paper;
http://climategate.nl/wp-content/uploads/2011/02/CO2_and_climate_v7.pdf
CO2 has very little measureable effect on atmospheric temperatures.
wayne: Without water vapor having a continuum over those same frequencies,
Phil.: It doesn’t so no problem there.
Phil, this HITRAN paper seems to disagree with your conclusion and mostly it is speaking of arctic again, little water vapor. I am speaking of the other 92% of the Earth and there the continuum does exists as this paper warns, that individual lines cannot be decerned except in very dry conditions.
See: http://www.cfa.harvard.edu/atmosphere/publications/2007-Diet-JQSRT-XXX.pdf
Seems so many of your points only hold in the dry arctic. I’ll take the other 92% moist Earth when speaking generalities.
wayne says:
March 28, 2011 at 1:34 am
wayne: Without water vapor having a continuum over those same frequencies,
Phil.: It doesn’t so no problem there.
Phil, this HITRAN paper seems to disagree with your conclusion and mostly it is speaking of arctic again, little water vapor.
No it doesn’t, where does it say that H2O has a continuum in the 15 micron region?
I am speaking of the other 92% of the Earth and there the continuum does exists as this paper warns, that individual lines cannot be decerned except in very dry conditions.
See: http://www.cfa.harvard.edu/atmosphere/publications/2007-Diet-JQSRT-XXX.pdf
Seems so many of your points only hold in the dry arctic. I’ll take the other 92% moist Earth when speaking generalities.
Actually, you chose the data and I explained the consequences of removing CO2 from that data, so now you want to change? That’s rather disingenuous of you.
Sorry Phil., can go no further. I thought mistakenly that you would be able to read a bit between the lines in the text of that last link I gave you. It does (somewhat hidden) mention the continuum nature of water vapor. Why is it there: pressure, self-broadening, foreign-broadening, dimers, mutimers, all of those exist in our atmosphere. But, it is evident you do not think there exists a water vapor continuum, I do. Here’s some links and papers if you want to learn more on this subject:
Water vapour continuum
In addition to the spectral lines, it has long been recognized that water vapour possesses a continuum absorption which varies relatively slowly with wavelength and pervades the entire IR and microwave spectral region. This has a marked impact on the Earth’s radiation balance with consequences for understanding present day weather and climate and predicting climate change. It is also important for remote sensing of the Earth and its atmosphere.
Discovered by Hettner (1918) as a low-frequency component of water vapour absorption in atmospheric transparency window 8-14 mcr, this phenomenon remained unexplained for 20 years, until Elsasser (1938) suggested that the continuum is an accumulated far-wing contribution of strong water vapour spectral lines from neighbour bands. This hypothesis was generally accepted until the end of 70th years when the strong quadratic pressure dependence of the continuum absorption (which could not be explained by Lorentz (1906) line profile) as well as the strong negative temperature dependence have been detected (Bignell et al.,1963; Penner and Varanasi,1967). In this connection Penner and Varanasi (1967) and Varanasi et al. (1968) suggested that the main contribution to the self-continuum could be caused not by far wings of water monomer lines but rather by water dimers. Similar assumption was made also by Viktorova and Zhevakin (1967) for microwave spectral region.
The dimer model have explained quite easily the pressure and temperature dependencies of the self-continuum absorption observed since then in many experiments (Mc Coy et al. 1969; Bignell, 1970; Burch, 1970; etc.). Since that time a long scientific discussion has started between adherents of the “monomer” (or “far-wings”) and the “dimer” nature of the water vapour self-continuum, which is continuing up to the current time.
On the one hand, more sophisticated (than Lorentz theory) ab-initio (Tvorogov et al. 1994; Ma and Tipping 1999, 2002; etc.) and semi-empirical (Clough et al. 1989, 1995, etc; Mlawer et al. 1999; etc.) line shape models have been developed, which could explain quite well the experimental facts mentioned above, and due to which the dominating role of the far wings of water vapour lines in the continuum absorption, especially in atmospheric conditions, is most commonly accepted today.
On the other hand, water dimers have been and are being often discussed as a possible component of the water self-continuum absorption (Lowder, 1971; Penner, 1973; Roberts et al. 1976; Arefev and Dianov-Klokov 1977; Montgomery, 1978; Dianov-Klokov et al. 1981; Varanasi, 1988; Devir et al. 1994; Vigasin et al. 1989, 2000; Cormier et al. 2005, etc.).
Finally, collision-induced absorption, resulting from the generation of a short-lived complex of water vapour and colliding molecules, has been proposed as a dominant within water vapour bands in the recent MT_CKD continuum model (Mlawer et al., in preparation, http://rtweb.aer.com/continuum_frame.html).
The possibility of both collision-induced and water dimer marked contribution to the water continuum absorption is however highly disagreed by Tipping (personal communication; Brown and Tipping, 2003). This point of view is shared by Vigasin only in respect to the free pair states, which negligible role as compared to the metastable or true bound water dimers at near-room temperatures has been shown by Vigasin (1991) and by Epifanov and Vigasin (1997) on the basis of preliminary statistical partitioning of the pair states in water vapour.
Thus, a deep controversy on the nature of the water vapour continuum still remains unresolved. The atmospheric science community has largely sidestepped this controversy, and has adopted a pragmatic approach. Most radiative transfer codes used in climate modelling, numerical weather prediction and remote sensing use a semi-empirical formulation of the continuum – CKD-model (Clough et al. 1989). This formulation was tuned to available (mostly laboratory) observations in rather limited (far-infrared) spectral regions.
The CKD model has served the community extremely well but we lack confidence that its semi-empirical formulation works at wavelength, or in atmospheric conditions, away from those in which it has been tested. This lack of confidence is exacerbated by the recent up-to-date theoretical (Schofield and Kjaergaard, 2003; Daniel et al. 2004; Scribano et al. 2006) and experimental (Vigasin et al. 2000, 2005; Ptashnik et al. 2004, 2005, 2006; Cormier et al. 2005; Paynter et al. 2007) studies that very well correlate and supplement each other, indicating all together the marked water dimer contribution to the water vapour self-continuum in some spectral regions.
( exerpt from: http://www.met.reading.ac.uk/caviar/water_continuum.html )
wayne says:
March 28, 2011 at 11:00 pm
Sorry Phil., can go no further. I thought mistakenly that you would be able to read a bit between the lines in the text of that last link I gave you. It does (somewhat hidden) mention the continuum nature of water vapor. Why is it there: pressure, self-broadening, foreign-broadening, dimers, mutimers, all of those exist in our atmosphere. But, it is evident you do not think there exists a water vapor continuum, I do. Here’s some links and papers if you want to learn more on this subject:
That it exists is one thing, saying that it makes a significant contribution in the 15 micron region compared with CO2 is quite another, it does not.
Joel Shore says on March 27, 2011 at 5:03 pm:
“You are very confused about the reason why adiabatic cooling happens. It has nothing (or almost nothing) to do with the increase in area. It has to do with the expansion of air due to the decrease in air pressure (because the air pressure is due, essentially, to the weight of the air above), not because the surface area is increasing.”
I think you just love to “pick nits” Joel. I believe I said: “as the area the air-molecules occupy increases they lose their heat proportionately.”
Of course air pressure is due to the weight of the air above. If it is not then whosoever sold me my barometer sold me a pup. – Pressure is ‘all in all’ related to; gravity, density, height and molecular mass. – I was not attempting to give you a lecture on adiabatic cooling, but since you state; “It has to do with the expansion of air due to the decrease in air pressure”, – I think I have got to ask: what do you think the air expands into, a smaller space perhaps? – It is the space or area between the air molecules that expands Joel, not the various air molecules and atoms; thereby the said atoms and molecules get more room to move around in, thus decreasing “interference friction”. Which, as I am sure you know, lead to a reduction in temperature?
Ok, ok, – so just in case you should insist the molecules do expand too – then yes, maybe they do to a certain extent – and yes I do know that is a logical possibility.
By the way, your workings out of all those square meters (m²) are all well and good as long as you put them side by side like a shell around the earth, but I am quite sure those “square meters” which radiate energy back out to space are in many layers (too many to be counted or guessed at). I doubt very much there can be just one “layer of (m²)“ containing just a few radiating molecules each. It would perhaps be better to consider the meters cubed (m³) as being occupied by air molecules.
Why do you mix the Stefan-Boltzmann Equation into this soup, this has got very little to do with losses from radiation waves? It has more to do with the fact that the air gets thinner. There is a scale for that too you know. I know you know because you yourself have put figures on the “lapse Rate”
Hmm, now let’s see what my pilot instructions have got to say about that one:
“In factoring in the influence of temperature on aircraft performance we shift to the concept of density altitude—that is, the higher the temperature, the higher the density altitude. The formula is as follows: Density altitude = Pressure altitude + (100 x [actual temperature – standard temperature] )
Okay, you may be asking “what the heck is ‘standard temperature’”. The standard temperature at sea level is 15° C, and the standard temperature lapse rate is 2° C/1000’. It actually is 1.98° per 1000’, but the .02 that is missing never hurt anyone. (And pilots still use feet (‘) by the way.) What then is the standard temperature for an airport with an elevation of 2000’? The answer is 11° C. As we know, temperature will decrease 2° C for every 1000’ increase in altitude (15 – 4 = 11).” You see it is much easier than the Stefan-Boltzmann Equation.
Vertical profiles of pressure and temperature observed in the atmosphere are closely linked. In other words, pressure decreases exponentially with altitude. At 80 km altitude the atmospheric pressure is down to 0.01 hPa, meaning that 99.999% of the atmosphere is below that altitude.
Joel, nobody on this earth knows all there is to know about this subject so there is no need to pretend you are the one who does.
But only the fact that the existence of “air molecules” diminishes as altitude increases has anything to do with lowering temperatures. Pressure is irrelevant.
O H Dahlsveen says:
March 29, 2011 at 2:23 pm
Vertical profiles of pressure and temperature observed in the atmosphere are closely linked. In other words, pressure decreases exponentially with altitude. At 80 km altitude the atmospheric pressure is down to 0.01 hPa, meaning that 99.999% of the atmosphere is below that altitude.
In the atmosphere I fly my plane in pressure decreases linearly with altitude!
O H Dahlsveen,
I no longer can figure out what point you are even trying to make. It was not nitpicking to point out that whatever vague point you seemed to be trying to make in your previous post was utterly negligible compared to the understood effects.
I’ll just remind you that I am not the one who came into this thread claiming of a well-founded piece of science, “You should have no problem at all in dissecting it and then expose it as some kind of juvenile science fiction which has no place among grown ups” and then proceeded to show how little you actually understood about the diagram that you were criticizing in this manner. I, unlike you, am well aware of how little I know compared to the experts.
Bryan says:
March 28, 2011 at 12:40 am
wayne
Thanks for your comments.
Have you read this paper;
http://climategate.nl/wp-content/uploads/2011/02/CO2_and_climate_v7.pdf
CO2 has very little measureable effect on atmospheric temperatures.
——–
Bryan, just noticed this. I’ve now downloaded it. On scanning, it looks like it might take a while to properly understand it in depth. Thank you.
Joel Shore says on March 29, 2011 at 5:59 pm:
“I no longer can figure out what point you are even trying to make.” – and: “I’ll just remind you that I am not the one who came into this thread claiming of a well-founded piece of science, “You should ——— how little you actually understood about the diagram that you were criticizing in this manner. I, unlike you, am well —-“”
Joel, my point is that I am not the one who believes it matters to the temperature here on this planet if energy that is taken away from the surface by radiation is returned to the surface by radiation. Even if the “returning agents” are called GHGs.
You are quite right; I actually understood very little about the diagram that I was criticizing. – What has improved is my understanding of how you believe the diagram was made. But that does not improve the quality of the diagram which, in my opinion, shows a meaningless circuit of energy between the surface & the GHGs.
The only way any kind of heat can leave the surface is by conduction between surface and atmosphere and the subsequent convection. – GHGs cannot stop convection.
How does your “well founded piece of science” explain how one form of energy that has been absorbed by an object and transformed into “kinetic energy” can be re-radiated time and time again? In my opinion, it can not – it is convected.
Kinetic energy, by the way, is ‘atoms or molecules in motion’ – and temperature is a measurement of the speed of that motion.
But if you no longer can figure out what point I am trying to make then I shall take responsibility for that. If I am not clear enough for you, then I’ll say no more.
Phil. Says on March 29, 2011 at 5:20 pm:
“In the atmosphere I fly my plane in pressure decreases linearly with altitude!”
Phil, I always flew mine in an atmosphere where the temperature decreased linearly and the pressure decreased exponentially. …
O H Dahlsveen says:
March 30, 2011 at 12:12 pm
Phil. Says on March 29, 2011 at 5:20 pm:
“In the atmosphere I fly my plane in pressure decreases linearly with altitude!”
Phil, I always flew mine in an atmosphere where the temperature decreased linearly and the pressure decreased exponentially. …
Really what planet was that on? Here on Earth it varies linearly at a rate of ~100 hPa/800 m, what sort of altimeter did you use the conventional aneroid barometer type connected to the static port wouldn’t work too well?
Phil. Says on March 30, 2011 at 8:41 pm:
“Really what planet was that on? Here on Earth it varies linearly at a rate of ~100 hPa/800 m, what sort of altimeter did you use the conventional aneroid barometer type connected to the static port wouldn’t work too well?”
Phil, why don’t you forget about your altimeter for a minute, I am not even be going to try to explain to you how it works, – instead put the following question into your search engine; Does pressure decreases exponentially with altitude? and see what comes up. – Or go directly to: Atmospheric Pressure and Altitude – Exponential Functions
Phil.:
I have to agree with O H Dahlsveen on this. The decrease with pressure with altitude is approximately exponential. (It would be exactly exponential if the temperature were constant and so density and pressure were directly proportional; although temperature is not constant, the deviation is not that dramatic on an absolute temperature scale.) Of course, near enough to the earth’s surface, the exponential looks like a linear drop-off, but clearly such a linear drop-off can’t…and doesn’t…continue forever.
The exponential fall-off follows from the fact that the rate of decrease of pressure with height is proportional to density, which by the ideal gas law is proportional to pressure itself if temperature is constant.
O H Dalhsveen:
Well, ultimately you can believe whatever you want to believe. However, don’t fool yourself into thinking that this changes what the actual facts are.
And, how do you conclude that? Everything that has a nonzero temperature radiates, unless its emissivity is identically zero over all wavelengths. In fact, the emissivity of the earth’s surface is very close to 1 throughout the infrared.
Yes, conduction plays a role too. But, ultimately, the only significant communication between the earth and its atmosphere with space is via radiation Convection, to a first approximation, just ends up enforcing the lapse rate in the troposphere being set by the appropriate (wet or dry) adiabatic lapse rate.
Ah…Why wouldn’t it be? Objects at a nonzero temperature radiate.
More or less correct…although the simple relation between speed and temperature only holds for an (ideal) gas. Also, temperature is due to the random component of the motion.
The simple point is this: Why don’t you just take your own advice and admit that you don’t know everything and that the scientists working in this field are likely the ones who understand it better, not you? A little humility is all that we ask. If the Trenberth and Kiehl diagram was so trivially-incorrect as you seem to think it is, by what sort of mass conspiracy or delusion do you believe scientists have accepted it?
Joel Shore says on March 31, 2011 at 10:22 am:
“Well, ultimately you can believe whatever you want to believe. However, don’t fool yourself into thinking that this changes what the actual facts are.”
I know that, facts are facts and one fact is that nobody can predict the future. We can only, at best look at past history and say that if history repeat itself then “so and so” is likely to happen. Past history, from whichever source it comes, has never shown that CO2 has been a climate driver. That is a fact.
Anyone who uses the Kiehl & Trenberth (K&T) diagram’s 342 W/m² incoming solar radiation as an average, may easily fool him- or herself into using that as a 24/7 continues solar irradiation factor. If so, then of course they are going to get global warming. In the real world only half of any object (or in our case, globe) that orbits the Sun is going to be irradiated at any one time, and that is one fact that must not be overlooked.
Even Dr. Roy Spencer says in his ‘Comments on Miskolczi’s (2010) Controversial Greenhouse Theory’ on August 5th, 2010: “The heat capacity of air is somewhat over 1,000 Joules per kilogram per degree C, which means it takes 1,000 Joules of energy to raise the temperature of 1 kilogram of air by 1 deg. C. Conveniently, in the lower atmosphere 1 kg of air corresponds to about 1 cubic meter (1 m3) of air. So, for a 1 meter thick layer of air, 1,000 Watts per sq. meter (W m-2) heating applied for 1 sec would raise the temperature by 1 deg. C. Or, since there are 86,000 seconds in a day, it would take (1000/86,000) = 0.01 Watts per sq. meter to get 1 deg. C per day warming rate”.
Take note here Joel he (ok he rounds the 24 hours of sunshine off to 86000 seconds but that is not important.) makes the mistake of warming the air for 24 hours. – What is important is that he neglects the simple fact that the 1 Kg of air will warm for 12 hours and then cool for 12 hours.
The question then must be: “how much of the warming that happens during the day is stored in the Earth System during the night?” – We do know that outgoing radiation from the Earth does happen 24/7. – And for that, I do not know what the actual facts are.
Most of your other points you have answered yourself as you seem to agree that temperature follows convection aloft until it is removed by adiabatic means. Therefore radiation happens only at the top of the atmosphere.
And your last point: “The simple point is this: Why don’t you just take your own advice and admit that you don’t know everything and that the scientists working in this field are likely the ones who understand it better, not you? A little humility is all that we ask. If the Trenberth and Kiehl diagram was so trivially-incorrect as you seem to think it is, by what sort of mass conspiracy or delusion do you believe scientists have accepted it?”
I may be wrong but I did not think I was giving you the impression that I think I know it all. – You yourself on the other hand have, more than once, given me the impression that you think I know next to nothing, and as far as I know I have not protested.
Joel Shore says on March 31, 2011 at 10:22 am:
“Well, ultimately you can believe whatever you want to believe. However, don’t fool yourself into thinking that this changes what the actual facts are.”
I know that, facts are facts and one fact is that nobody can predict the future. We can only, at best look at past history and say that if history repeat itself then “so and so” is likely to happen. – Past history, from whichever source it comes, has never shown that CO2 has been a climate driver. That is a fact.
Anyone who uses the Kiehl & Trenberth (K&T) diagram’s 342 W/m² incoming solar radiation as an average, may easily fool him- or herself into using that as a 24/7 continues solar irradiation factor. If so, then of course they are going to get global warming. – In the real world only half of any object (or in our case, globe) that orbits the Sun is going to be irradiated at any one time, and that is one fact that must not be overlooked.
Even Dr. Roy Spencer says in his ‘Comments on Miskolczi’s (2010) Controversial Greenhouse Theory’ on August 5th, 2010: “The heat capacity of air is somewhat over 1,000 Joules per kilogram per degree C, which means it takes 1,000 Joules of energy to raise the temperature of 1 kilogram of air by 1 deg. C. Conveniently, in the lower atmosphere 1 kg of air corresponds to about 1 cubic meter (1 m3) of air. So, for a 1 meter thick layer of air, 1,000 Watts per sq. meter (W m-2) heating applied for 1 sec would raise the temperature by 1 deg. C. Or, since there are 86,000 seconds in a day, it would take (1000/86,000) = 0.01 Watts per sq. meter to get 1 deg. C per day warming rate”.
Take note here Joel he (ok he rounds the 24 hours of sunshine off to 86000 seconds -but that is not important.) makes the mistake of warming the air for 24 hours. – What is important is that he neglects the simple fact that the 1 Kg of air will warm for 12 hours and then cool for 12 hours.
The question then must be: “how much of the warming that happens during the day is stored in the Earth System during the night?” We do know that outgoing radiation from the Earth does happen 24/7. – And for that, I do not know what the actual facts are.
Most of your other points you have answered yourself as you seem to agree that air temperature follows convection aloft until it is removed by adiabatic means.
Therefore radiation happens at the top of the atmosphere.
And your last point: “The simple point is this: Why don’t you just take your own advice and admit that you don’t know everything and that the scientists working in this field are likely the ones who understand it better, not you? A little humility is all that we ask. If the Trenberth and Kiehl diagram was so trivially-incorrect as you seem to think it is, by what sort of mass conspiracy or delusion do you believe scientists have accepted it?”
I may be wrong but I did not think I was giving you the impression that I think I know it all. – You yourself on the other hand have, more than once, given me the impression that you think I know next to nothing, and as far as I know I have not protested.