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.
Phil says of my 3 options above
…..”None of the above, the cooler object will warm up until it is in equilibrium with the incoming radiation from the hotter object resulting in more radiating reaching the hotter object which will also increase in temperature until it is in equilibrium too.”…..
So it appears that Phils answer to all questions on thermodynamics is…..
The heat death of the Universe
Bryan says:
March 11, 2011 at 9:23 am
Phil. says:
“What on earth is the ‘quality’ of radiation?”
The ‘quality’ of radiation or energy generally is its ability to do work or in other words turn into other energy forms.
If you google the appropriate words you will find plenty of hits particularly from solar energy capture systems.
This is about science, the question you didn’t try to answer is what’s its units?
A quantum of light has a wavelength and frequency, its energy is given by the product of h and frequency. What’s the equation for quality?
Bryan says:
March 11, 2011 at 9:29 am
Phil says of my 3 options above
…..”None of the above, the cooler object will warm up until it is in equilibrium with the incoming radiation from the hotter object resulting in more radiating reaching the hotter object which will also increase in temperature until it is in equilibrium too.”…..
So it appears that Phils answer to all questions on thermodynamics is…..
The heat death of the Universe
Questions on matters of thermodynamics I answer with thermodynamics, what a concept!
Phil. says:
“What on earth is the ‘quality’ of radiation?”
So after informing you of something you knew nothing about wheres the;
Thank you Bryan?
……..” question you didn’t try to answer is what’s its units?”……..
I thought when you read the sources you could work that one out for yourself!
However sceptics are ever helpful!
“Quality” is a comparison.
Electrical Energy has a higher “quality” than an equal quantity of Heat Energy.
Black Body radiation centred around 2um has a higher “quality” than an equal quantity of Black body radiation centred around 20um
to Bryan
((So it appears that Phils answer to all questions on thermodynamics is…..
The heat death of the Universe))
The laws of thermodynamics are simply a handy way of examining any closed system. They are the laws science uses to construct machines, toys, etc. That’s all. Period.
There is no evidence that the universe is a closed system. On the contrary, the evidence is overwhelmingly in favor of a open system, not closed.
What are the most powerful, energetic objects in the universe?
Quasars.
They are pouring additional energy into the universe.
But almost nothing about them is understood.
Phil. says:
March 11, 2011 at 7:51 am
For a temp of 270K the peak frequency is 15.9 THz corresponds to 18.9 microns.
——–
Phil, respectably, it seems you missed a factor in this calculation as explained by this paper: http://www.journal.lapen.org.mx/sep09/12_LAJPE_303_Lianxi.pdf
Best to just use equation λmax (µm) = 2897.77/T without needing to using the c/1.760 correction in subsequntly converting frequency back to wavelength with Wien’s frequency form of the equation.
For a temp of 270K the peak wavelength is 2897.77 µm·K/270K = 10.73 µm.
Dave Springer:
Look elsewhere than Wikipedia when possible for clarity, you are probably now totally confused, and yes, the top charts are incorrect.
wayne says:
March 11, 2011 at 10:31 am
Hey Wayne, before you go dissing wikipedia you ought to read the list of references for the papers you present in your comments.
The paper above (Lianxi) which you say explains a missed factor in Wien’s Law has a reference [5] which is to the Wikipedia article on Planck’s Law.
Physician, heal thyself. 🙂
Phil. says:
March 11, 2011 at 9:57 am
“What’s the equation for quality?”
I think you’re being facetious but for the benefit of everyone else…
It depends on the application. Carnot was probably the first to quantify it for heat engines:
μC = (Ti – To) / Ti
where
μC = efficiency of the Carnot cycle
Ti = temperature at the engine inlet (K)
To = temperature at engine exhaust (K)
As a general rule of thumb energy quality is like pornography. It’s difficult to define but you know it when you see it.
For instance a solar pond with 1 million pounds of water that is 1 degree F above ambient air temperature has 1 million BTUs of energy available to do useful work but it’s exceedingly poor quality. A boiler with 1000 pounds of water 1000 degrees F above ambient air temperature also has 1 million BTUs of energy available to do useful work and it’s high quality energy.
Generally speaking water that is below the boiling point at STP, say 99C, is considered poor quality energy as it has a low Carnot efficiency. But if your application is supplying hot water for home use (clothes washing, hot shower, etc.) instead of running a heat engine then it’s very high quality energy.
Another example, a cloud might have an electric charge of 1 megawatt/hour but it’s low quality energy. A bank of Lithium/Ion batteries with an electric charge of 1 mw/h is high quality energy if you have an electric vehicle but it’s pretty low quality if you have a horse & buggy. 🙂
Richard E Smith says:
March 11, 2011 at 8:45 am
Since I’m getting credit for it in this thread I get to name it. I’m calling it the “engineer’s version” because it’s the theory of operation behind millions of IR CO2 sensors around the world used to control ventilation systems in commercial structures.
http://v2010.raesystems.com/~raedocs/App_Tech_Notes/Tech_Notes/TN-169_NDIR_CO2_Theory.pdf
I’m not much on theory that has no demonstrated its usefulness in practical applications. In this case the absorption of longwave infrared by CO2 and thermalization of the other non-absorptive gases in the atmosphere is well established fact employed in practical applications around the world.
Hans says:
March 10, 2011 at 8:00 pm
Glad to see someone who deeply understands physics–entropy, in particular–and has the patience to explain it all to those weaned on soft science miscomprehensions upon which the “radiative greenhouse” paradigm rests. Danke schoen, Hans, very well done!
“Phil. says:
What on earth is the ‘quality’ of radiation?”
That would be something like the ability do to work at the radiative equilibrium temperature of the matter that this radiation came from. So with the high frequency radiation of the sun at 5777 K versus the 255 K radiation of earth, the efficiency according to the Second law for the sun radiating to an object in space at say 100 K would be 1-(100/5777) = 98% and for earth doing this 1-(100/255) = 61%.
And for backradiation on earth from 255K towards 288 K it would be 1-(288/255) = – 13%, that’s a nasty negative heat engine.
RJ, Will, wayne, whoever said this:
And I see you as a luke warmer not a true sceptic. You are sceptical of the overstated alarmists predictions not the GHG science itself.>>>>
I’m insulted. I am a hardcore skeptic. But that doesn’t change the fact that some elements of the AGW position are correct. To be an EFFECTIVE skeptic, set the record straight and help people get proper perspective, one needs to recognize those elements of the AGW argument that are correct, and attack them where they are dead wrong and also where they highly misrepresent the facts to create a false impression.
Stephan-Boltzman Law provides the math formula for calculating exactly how much energy flux a surface will emitt at a given temperature. You can do the calculation at an ambient temperature of -100C, 0, +100C and you will get the same number every time. You can do the calculation with another surface in proximity at -1000, +1,000C or 1,000,000 C, and you will STILL get the exact same answer. And those answers have been verified thousands upon thousands of times by experimentation.
Unless you can disprove SB, there’s very little logical thought to follow. Since the energy flux leaving the surface is unaffected by the temperature of objects around it be they colder or hotter, the photons leave at that specific rate. If a colder surface is in proximity, it is subject to the exact same laws. The colder surface emitts the exact same energy flux it would have not matter what environment it is in or what it is proximate to. The photons the colder surface emitts travel away, and if they strike a surface capable of absorbing them, they will be absorbed, warming that surface up by the amount of energy they carried, not matter what the temperature of the surface is.
At days end, the GHG explanation of CO2 IN ISOLATION OF ALL OTHER FACTORS is correct. It is however completely misrepresented by the AGW crown. The magnitude is tiny, it is modelled ats w/m2 at the top of the atmosphere which is ridiculous, feedbacks are ignored, exagerated, or even calculate with the wrong sine, and on and on and on.
There is SO MUCH to take the IPCC to task for where they are dead wrong or obviously manipulative. Take for example their calculation that doubling CO2 will produce a direct 3.7w/m2 at TOA which in term results in a 1 degree temperature increase. Here’s a brief rundown of the stuff they document in the fine print, but you’d never know if from the big bolded explanations:
1. They calculate +1 degree against the “effective blackbody” temperature of earth. That’s about -19C and occurs at about 15,000 feet altitude. Use their same exact physics to calculate the surface temperature change and you get only 0.6 degrees.
2. They then say that changes in RF from GHG are usefull for calculating changes in the effective black body temperature of earth, but that these may not translate into surface temp changes in linear fashion, and they EVEN say that there may be NO surface change in temperature, but that the climate will still change dramaticaly. Say what huh?
3. At no point do they explain their +1 degree in context other than average temperature. More hooey, there is no such thing. Assume worst case of +1 at effective black body, SB Law yields 0.6 at surface (it is is in fact linear which I doubt) average of +15. Now let’s use SB Law to calculate not the average increase, but the increase under various conditions. Like at +30 at the equator warms up to +30.1 while -50 in the arctic warms up to -46. See the issue here? The hottest parts of the planet, on the hottest days, change very little, most of the change comes in the coldest parts, during winter, at night time lows.
4. Then the vaunted IPCC makes what I consider to be the most egregious misrepresentation of all. They admit via their own math that CO2 is subject to the laws of diminishing return, that it is logarythmic. Then the merrily move forward with scenario after scenario showing what would happen under various circumstances, conveniently leaving out that the amount of fossil fuel we would need to consume to achieve those levels is orders of magnitude beyond what we could actually burn even if all we did with it was burn it!
I could go on…and on… and on… the CO2 backradiation argument is a rat hole that consumes everyone’s time, the basic physics of GHG is correct, but the magnitude, exagerated as far as the IPCC can possibly exagerate it through the information they bury in the fine print, is so small that it is at best splitting hairs.
So igloos work, if you’ve done any winter camping you know that they have a vent at the top to vent carbon dioxide laden air from exhaled breath, that they have several air changes per night as a result, that the warmest air leaves first and is replaced by the coldest air from entrance, and STILL the person inside is warmer than if they were outside the igloo, and the extra warmth is from backradiation from the colder surfaces of the igloo.
Stop fighting reality, start fighting the real battle.
CO2 is logarythmic, we cannot possibly produce enough more to make a significant difference.
The IPCC calculations are at a height in the atmosphere that does not translate to the same temp changes on the surface, and they even admit that there may be NO surface temp change.
The IPCC glosses over the fact that any warming will be insignifanct in areas that are already warm, and most pronounced in cold places where it makes the least possible difference.
With ammunition like that we’re fighting about backradiation why?
If someone says that a g
Say what? It seems like saying $1000 in $2 bills has a higher “quality” than an equal amount, $1000 in $20 bills.
Phil gave the science behind what Bryan calls “quality” when, in an earlier comment (timestamped March 11, 2011 at 9:23 am) he wrote: “A quantum of light has a wavelength and frequency, its energy is given by the product of h and frequency.”
So, using Phil’s scientific explanation, a 2μ photon, having a higher frequency, would convey ten times as much energy as a 20μ photon, which is at 1/10 th the frequency.
According to Wikipedia, the energy and momentum of a photon depend only on its frequency (ν) or inversely, its wavelength (λ): E = hc/λ [where E is Energy, h is Plank’s constant, c is the speed of light, and λ is wavelength].
However, in our discussions here, we are talking about equal quantities of Energy, (measured, for example, in Joules) on average, arriving at the Earth in the form of shortwave radiation from the Sun and, on average, leaving the top of the Atmosphere in the form of longwave radiation. So, using Bryan’s misinterpretation of “quality”, the Sun sends Earth a quantity X Joules of Energy in 2μ photons and the Earth’s Atmosphere sends an exactly equal amount, X Joules of Energy in 20μ photons out to Space. The number of photons from the Sun to Earth is different than the number from the Atmosphere to Space, but the quantity of Energy, on average, is equal.
Good commentary and summary. The IPCC is notably more honest in the fine print that the political editors haven’t thoroughly cleansed.
Except — CO2 ain’t logging any r(h)ythms. But its effect declines logarithmically.
😉
:pPp
wayne says:
Sorry, but as a physicist, I can say that what you have just said is basically complete and utter nonsense. Okay…There is a germ of truth in your idea of the relation between absorption and emission of radiation (which is not exactly what you say, but seems to be what you are sort of getting at if we are generous in our interpretation of what you have written). In fact, by Kirkhoff’s Law says they are equal; HOWEVER, that equality only holds wavelength by wavelength. Thus, it does not hold for the total wavelength-integrated emissions and absorptions except in the case when two objects are at the same temperature (and thus have the same emission spectrum).
The sun and the earth are at very different temperatures and thus emit radiation with very different spectra…In fact, the temperatures are so different that their spectra are not only very different but even have very little overlap. As a result, there is no rule whatsoever that an increase in “insulation” needs to be accompanied by a compensating decrease in the amount of solar radiation that makes it through the atmosphere to reach the earth.
I’m not going to keep an open mind about well-understood and settled basic physics just because someone does not understand it (and presents no empirical evidence whatsoever to back up his views and overturn the last couple centuries of our understanding of thermodynamics and radiative physics). That’s openmindedness to the point of letting one’s brains fall out.
Ira Glickstein, PhD says:
March 11, 2011 at 4:04 pm
“So, using Bryan’s misinterpretation of “quality”, the Sun sends Earth a quantity X Joules of Energy in 2μ photons and the Earth’s Atmosphere sends an exactly equal amount, X Joules of Energy in 20μ photons out to Space. The number of photons from the Sun to Earth is different than the number from the Atmosphere to Space, but the quantity of Energy, on average, is equal.”
Concerning Bryan’s quality, he is correct because that would be the ability do to work at the radiative equilibrium temperature of the matter that this radiation came from. So with the high frequency radiation of the sun at 5777 K versus the 255 K radiation of earth, the efficiency according to the Second law for the sun radiating to an object in space at say 100 K would be 1-(100/5777) = 98% and for earth doing this 1-(100/255) = 61%.
For backradiation on earth from 255K towards 288 K this would be 1-(288/255) = – 13%, that’s would be a negative heat engine.
Concerning quantity of Energy being equal, yes. But there are three flows in play at the surface: LWR in, IR out and HEAT out. So the IR coming from the surface is lower in quantity and lower in quality than the LWR hitting the surface. So IR = LWR – HEAT.
This heat has its own ways (thermal, evaporation) getting to the next higher layer at a lower temperature or the heat would not be there (no flow), and has no relation with the IR photons but with the delta T.
Backradiation from this next layer going down can occur if there is interaction with matter at this lower temperature, but it misses the HEAT component that does not go down but further up.
So backradiation hits the surface again and is believed to create more heat so we would get IR new = IR (old) – new HEAT.
And this cannot be, because IRnew would thus have to leave from a surface with a LOWER temperature. Or perhaps backradiation cools the surface?
Domenic:
Wow…That was written by one of the co-authors of “Slaying the Sky Dragon”?!? That’s really embarrassing. If I were an AGW skeptic, I would be running as fast as possible to disassociate myself from that book and anyone remotely involved with it! The fact that people like you are actually endorsing such scientific nonsense guarantees that you will continue to be regarded as “flat-earthers” by any serious scientists.
And, you demonstrate that by posting a bunch of pseudoscientific nonsense?!? Let me give you a hint…If you actually want to convert serious scientists to your point-of-view, you would be much better off being a little more discerning in what arguments you choose to embrace. Stick with defending arguments for low climate sensitivity; they also may be pretty poor (e.g., as has recently been demonstrated regarding some of Roy Spencer’s work: http://arthur.shumwaysmith.com/life/content/roy_spencers_six_trillion_degree_warming ) but at least they aren’t patently ridiculous!
Hans says:
March 11, 2011 at 6:06 pm
… So backradiation hits the surface again and is believed to create more heat so we would get IR new = IR (old) – new HEAT.
And this cannot be, because IRnew would thus have to leave from a surface with a LOWER temperature. Or perhaps backradiation cools the surface?
Like your fresh style Hans. Same thoughts, different way to say it.
That brings to mind the one case where I have always considered back-radiation literally, and not merely figuratively, real and proper; that is the case when low clouds are actually at a higher temperature that the surface, warmed from condensation. It does happen, but may be somewhat rare.
In that case your last equation would show positive.
Speaking in terms of individual photons as is common in these discussions, this is the very case where there would be more photons beaming down back to the surface than leaving from the surface traveling upward, literally heat moving downward and warming it. True back-radiation. Still don’t like that term, but since that what it is called, I will continue to use it. This is really just normal radiative warming from warm clouds.
Trying to stay parallel, can you it put that way?
wayne says:
March 11, 2011 at 10:31 am
Phil. says:
March 11, 2011 at 7:51 am
For a temp of 270K the peak frequency is 15.9 THz corresponds to 18.9 microns.
——–
Phil, respectably, it seems you missed a factor in this calculation as explained by this paper: http://www.journal.lapen.org.mx/sep09/12_LAJPE_303_Lianxi.pdf
Best to just use equation λmax (µm) = 2897.77/T without needing to using the c/1.760 correction in subsequntly converting frequency back to wavelength with Wien’s frequency form of the equation.
For a temp of 270K the peak wavelength is 2897.77 µm·K/270K = 10.73 µm.
Nope I guess I’ll have to explain it again.
When you plot spectral radiance as a function of frequency you get a maximum at a frequency of 15.9 THz corresponds to 18.9 microns as correctly shown in the data above from Petty.
When you plot spectral radiance as a function of wavelength it is a different functional form and the maximum is at 10.73 µm. Both are correct you’re just looking at different representations of the curves.
Try here as a source for the various equations:
http://www.spectralcalc.com/blackbody/blackbody.html
Dave Springer:
Look elsewhere than Wikipedia when possible for clarity, you are probably now totally confused, and yes, the top charts are incorrect.
No they are correct, perhaps it’s some of the commenters on WUWT that are confused?
Hans says:
March 11, 2011 at 1:45 pm
“Phil. says:
What on earth is the ‘quality’ of radiation?”
That would be something like the ability do to work at the radiative equilibrium temperature of the matter that this radiation came from. So with the high frequency radiation of the sun at 5777 K versus the 255 K radiation of earth, the efficiency according to the Second law for the sun radiating to an object in space at say 100 K would be 1-(100/5777) = 98% and for earth doing this 1-(100/255) = 61%.
Which is nothing to do with the radiation, you can’t tell me what the ‘quality’ of 5μm radiation is for example.
Dave Springer says:
March 11, 2011 at 11:58 am
Phil. says:
March 11, 2011 at 9:57 am
“What’s the equation for quality?”
I think you’re being facetious but for the benefit of everyone else…
Not being facetious at all, so far no-one has answered the question, bear in mind what I asked was “What on earth is the ‘quality’ of radiation?”, the simple answer is that there is no such thing!
Domenic says:
March 11, 2011 at 9:09 am
It amazes me that so many are still chasing around the canard tossed out by the AGW people.
Just like “Hide the decline!”
“Hide the nitrogen, oxygen and water!”
They tell you to disregard the N2, O2 and H2O in the atmosphere.
They tell you to disregard the HUGE heat capacity and HUGE thermal mass represented by N2, O2 and H2O in the atmosphere.
Disregard the 99.05% of the atmosphere. It has no effect.
Focus only on the 0.05% CO2 that we tell you to.
The canard appears to be of your making, who among the ‘AGW people’ tells you that nonsense, no one tells you to ignore the thermal mass of N2 and O2, that’s the sink that absorbs the energy absorbed by CO2. You should however be aware that N2 and O2 aren’t capable of absorbing IR radiation.
Dave Springer says:
March 11, 2011 at 4:39 am
@wayne (con’t)
The one-way insulating effect of GHGs is why, in my blanket example, I use two black rocks which are both exposed to the sun during the day so they can heat up (equally) then just one rock has a blanket thrown over it at night. The next morning they are uncovered and the temperature of the blanketed rock will be higher than the unblanketed rock. The next day, since one rock is warmer in the morning than the other yet both will be exposed to the sun again getting the same amount of daytime heating, the rock that is blanketed at night will reach a higher daytime maximum temperature. This temperature increase will continue until a new (higher) daytime equilibrium temperature is reached. The hotter the rock is when the blanket is thrown over it at night the quicker it will lose heat through the blanket. Heat flow rate through the insulating barrier is proportional to the temperature difference between the warm and cold sides. As the difference increases heat is lost faster. It is that which prevents the blanketed rock from just getting hotter and hotter until it melts.
Sorry Dave, didn’t notice you had commented back, tsunami and all, thank the Lord more people were not lost.
But your example is a bit unreal in this aspect, you are physically removing the insulation from one rock only during the daytime, putting it back on during the night. Can’t do that for the atmosphere. Try running it again in your mind with the blanket left on it all the time, even during the day. One with a blanket, one without. What would the rocks show in their temperature profiles then?
To me they would be different temperature profiles for sure but it seems, off of the top of my head, that there would be two times every day that their temperatures would be identical, given enough days to equalize. The blanketed one would have less diurnal range. The emissivity and reflectivity of the blanket itself would be the controlling factor.
What would you guess?
See, I don’t believe one-way insulators exist in gases. To me, that very factor is why Venus with an atmosphere of 96.5% CO2 is approaching a mirror surface to solar radiation. The CO2 blanket that you seem to see cuts equally both ways, and you end up back at with no change at all. Physics is good at twisting you mind like that, forgotten factors. See Scarlet Pumpernickel’s link above concerning Venus. I found that very interesting. I have spent countless hours on Venus’s atmosphere, it’s pressure gradient, density gradient, lapse rate, temperature profile, trying to understand a union of all planetary atmospheres, but I was working the surface up. He worked top down. I give him a pat on the back for his method, even if it ends up having flaws. I learned a new approach there.
@ur momisugly davidmhoffer
I’ve always found winter camping very uncomfortable and I don’t do it if I can avoid it, however, now that I’ve gleaned some insight into the wonders of igloos I’m ready to give it another shot.
It takes quite a number of hours to build even a small one but I’m sure it’s well worth the effort since I will not have to pack in a tent or a down-filled sleeping-bag.
As I understand it, once in the snugness of my owner-built snow structure, I can safely remove my mukluks and caribou skin parka. These I can lay on the icy floor as a mat to reduce the dreaded conduction. Perhaps radiation from the floor would keep me warm but I’m not too sure of it.
I know that, inside my clothing, my skin temperature is about 22C and I know from experience that my body’s internal organs are able to maintain homeostasis when my skin is that temperature. It’s got to do with dilation of blood vessels, although I’ve read elsewhere that it’s quite different on mountain-tops.
So, I can confidently lie naked upon my folded clothing and feel the temperature of my skin rise to 23 degrees as the walls of the igloo benevolently shine their rays upon me. As this happens, the capillaries close to the surface of my skin will happily dilate so as to rid myself of excess heat and thus avoid the horrible fate of cooking from the inside.
I do have some apprehension about the snow’s ability to modulate its radiative re-heating of my person, but I assume that if the ice is heating me, it is perhaps doing it at the expense of its own temperature; that is to say, it’s getting colder.
There again, if cold ice can heat me so satisfactorily, what might even colder ice do?
David, you invoked, very convincingly, Stefan’s Law, and I know you don’t think much of the Second Law, but the First Law is starting to falter here, too.
Quality of energy has won itself a bad reputation in these parts but it’s the quantity I’m concerned about. How long can a person stay in an igloo before they spontaneously combust? Is there any way to control this relentless heating of oneself when surrounded by ice? If I put my parka back on will the ice stop with the heating?
Can I really have faith in you as my arctic adventure mentor? How do you know it’s radiation at work and not conduction and convection. After all, you’re a little off on how many air changes you think a person would need and you suggest that the vent is sited so as to shed heat as well as exhaust gases.
So we’ve got hot things heating cooler things, we’ve got cold things heating hotter things.
I suppose if two things are the same temperature, they just keep heating one another equally forever.
Why are you so keen to convince us that you’ve got it all figured out?
Is it lonely out there?
Oliver Ramsey;
You have got to be kidding. That’s a rebuttal? Ridiculous conjectures drawn from thin air and attributed to me? Followed up with reading my mind announcing that you know what I think, and then making fun of that? I musta some ticked you off at some point. I shall try and be civil in order to set the record straight if nothing else.
OR:It takes quite a number of hours to build even a small one (igloo)>>>
You can build a quinzee in a fraction of the time and they are a better shelter for one person.
OR:As I understand it, once in the snugness of my owner-built snow structure, I can safely remove my mukluks and caribou skin parka>>>
No, I never said that, and your sarcasm does nothing to advance the discussion. If you insist I be specific, it takes time for the warmth to build up inside, it might never get warm enough to take off anything, though in most cases you’ll wind up unzipping your coat a bit to cool off. But you’ll not freeze to death like you would outside the structure.
OR:So, I can confidently lie naked upon my folded clothing and feel the temperature of my skin rise to 23 degrees as the walls of the igloo benevolently shine their rays >>>
Again, I said no such thing. You want to lie naked in the hopes of warming up go ahead. You want to construe that I said the igloo would shine that strongly then fine, lest you put words in my mouth, I’ll answer that one too. If you stopped to think through the physics for a moment you might ask yourself how much benevolent sunshine there is shining out of your…body in the first place. The igloo doesn’t create more heat, it only passes a small portion of the heat radiated by your body back to you. So unless you yourself are hot enough to shine benificently upon those around you in the first place, you are just being ridiculous.
OR: I assume that if the ice is heating me, it is perhaps doing it at the expense of its own temperature; that is to say, it’s getting colder. >>>
Bingo! Everything radiates energy commensurate with its own temperature as defined by Stefan’s law. So yes, it is getting colder. But it isn’t “heating you” at its own expense. Its radiating energy at exactly the same rate it would if you were there or not. Since you are there some of it runs smack dab into you. Not enough to keep you from freezing to death since you were dumb enough to take your clothes off, but some.
OR: There again, if cold ice can heat me so satisfactorily, what might even colder ice do?>>>
Uhm…. heat you less satisfactorily? C’mon, no where did I say that the colder the ice was the more it could warm you.
OR: I know you don’t think much of the Second Law>>>
You clearly do not know what I think, you don’t even understand what I wrote. The Second Law is just as real as Stefan’s Law.
OR: How long can a person stay in an igloo before they spontaneously combust?>>>
Forever.
OR:Is there any way to control this relentless heating of oneself when surrounded by ice? If I put my parka back on will the ice stop with the heating?>>>
Per my previous comment, you only get a portion of what you yourself radiated out in the first place back. If you put your parka back on before you stupidly freeze to death, then YES! the ice suddenly be getting less energy radiated at it by you, and consequently radiate less back. For a while. Eventually your body heat will heat up the parka, and it will start radiating heat, a portion of which the ice will radiate back at you.
OR:How do you know it’s radiation at work and not conduction and convection. After all, you’re a little off on how many air changes you think a person would need and you suggest that the vent is sited so as to shed heat as well as exhaust gases.>>>
Because when you radiate heat, you lose energy at the rate defined by your temperature and Stefan’s Law. If you are dumb enough to to sit your naked but on ice, you will definitely have conduction, the rate at which you will lose energy to the ice via conduction will be massively higher than what you radiate, and far in excess of what your body can replace by burning calories. Best keep your pants and parka on, they are made of stuff that doesn’t conduct well. As for the vent, yes, it is sited at the top to exhaust gases, most notably the carbon dioxide from your breathing. Since the warmest air in the igloo is most likely your own breath, it will rise via convection, taking both the CO2 and the heat you breathed out with it.
In other words conduction is massively negative, and convection is also negative, that’s how I know that neither of them are what keep you warm inside an igloo.
OR: I suppose if two things are the same temperature, they just keep heating one another equally forever.>>>
Oddly, I know you meant that to be sarcastic, but you finally got one right.
OR: Why are you so keen to convince us that you’ve got it all figured out?
Is it lonely out there?>>>
Why are you so keen to misrepresent what I said, exagerate to the ridiculous claims that I never made, pretend to read my mind and be critical of the fictitious opinions you attribute to me, and end with the most devastating, sarcastic, cutting logic that you can summon up. “Is it lonely out there?”
You’re the one lying naked in the middle of an igloo freezing his appendages off and screaming see! I told you I wouldn’t spontaneously combust! So let me answer your question seriously.
The subject of climate change is WAY off the rails. The claims of the AGW crowd are preposterous, the warning of impending doom fictitious nightmares, and the solutions proposed at best a medicine for worse than the disease. AGW has become nothing more than a tool in the hands of those who grasp for power and wealth for themselves at the expense of those who are doing honest work, and at the expense of the poor and down trodden that they proclaim to be protecting.
I no more have it all figured out than do the climate “scientists” who spout doom and gloom while deleting anything that might contradict them. But there are certain aspects of how thermodynamics work that are known, they are the foundation upon which the AGW alarmism is built, and assailing a firm foundation with distorted criticisms of a ligitimate explanation wastes your time, my time, and discredits us as skeptics in front of the AGW scientists who happen to have taken the one piece of science they got right and built a house of cards upon it.
I’m keen to set the record straight with warmists and skeptics alike so that we can move on to discuss order of magnitude, feedback, distribution of change by lattidude and altitude, and all the other issues that make a mockery of the AGW claims. If you want to level a well thought out, valid criticism of my explanation, I’ll either answer with a better explanation or an hmmm never thought of that. But if all your going to do is throw up wild claims about I said as arguments, then I’ll just say this:
Those AGW dudes are planning on picking your pockets, and I’m keen to get their bullarky discredited before they get around to picking mine.
Joel Shore,
Thanks for catching that. After reading my own words back I should have been sure to mention the concept of shells, really any thickness. If a layer above “insulates” radiation going upward, then once given energy is above that same shell and is absorbed and radiated downwards that same shell will “insolate” to equally keep it outside the system. Same shell, same insolating property. Does that make it any clearer?