Guest Post by Ira Glickstein
This series began with a mechanical analogy for the Atmospheric “Greenhouse Effect” and progressed a bit more deeply into Atmospheric Windows and Emission Spectra. In this posting, we consider the interaction between air molecules, including Nitrogen (N2), Oxygen (O2), Water Vapor (H2O) and Carbon Dioxide (CO2), with Photons of various wavelengths. This may help us visualize how energy, in the form of Photons radiated by the Sun and the Surface of the Earth, is absorbed and re-emited by Atmospheric molecules. 
DESCRIPTION OF THE GRAPHIC
The animated graphic has eight frames, as indicated by the counter in the lower right corner. Molecules are symbolized by letter pairs or triplets and Photons by ovals and arrows. The view is of a small portion of the cloud-free Atmosphere. (Thanks to WUWT commenter davidmhoffer for some of the ideas incorporated in this graphic.)
- During the daytime, Solar energy enters the Atmosphere in the form of Photons at wavelengths from about 0.1μ (micron – millionth of a meter) to 4μ, which is called “shortwave” radiation and is represented as ~1/2μ and symbolized as orange ovals. Most of this energy gets a free pass through the cloud-free Atmosphere. It continues down to the Surface of the Earth where some is reflected back by light areas (not shown in the animation) and where most is absorbed and warms the Surface.
- Since Earth’s temperature is well above absolute zero, both day and night, the Surface radiates Photons in all directions with the energy distributed approximately according to a “blackbody” at a given temperature. This energy is in the form of Photons at wavelengths from about 4μ to 50μ, which is called “longwave” radiation and is represented as ~7μ, ~10μ, and ~15μ and symbolized as violet, light blue, and purple ovals, respectively. The primary “greenhouse” gases (GHG) are Water Vapor (H2O) and Carbon Dioxide (CO2). The ~7μ Photon is absorbed by an H2O molecule because Water Vapor has an absorption peak in that region, the ~10μ Photon gets a free pass because neither H2O nor CO2 absorb strongly in that region, and one of the 15μ Photons gets absorbed by an H2O molecule while the other gets absorbed by a CO2 molecule because these gases have absorption peaks in that region.
- The absorbed Photons raise the energy level of their respective molecules (symbolized by red outlines).
- The energized molecules re-emit the Photons in random directions, some upwards, some downwards, and some sideways. Some of the re-emitted Photons make their way out to Space and their energy is lost there, others back down to the Surface where their energy is absorbed, further heating the Earth, and others travel through the Atmosphere for a random distance until they encounter another GHG molecule.
- This frame and the next two illustrate another way Photons are emitted, namely due to collisions between energized GHG molecules and other air molecules. As in frame (2) the Surface radiates Photons in all directions and various wavelengths.
- The Photons cause the GHG molecules to become energized and they speed up and collide with other gas molecules, energizing them. NOTE: In a gas, the molecules are in constant motion, moving in random directions at different speeds, colliding and bouncing off one another, etc. Indeed the “temperature” of a gas is something like the average speed of the molecules. In this animation, the gas molecules are fixed in position because it would be too confusing if they were all shown moving and because the speed of the Photons is so much greater than the speed of the molecules that they hardly move in the time indicated.
- The energized air molecules emit radiation at various wavelengths and in random directions, some upwards, some downwards, and some sideways. Some of the re-emitted Photons make their way out to Space and their energy is lost there, others back down to the Surface where their energy is absorbed, further heating the Earth, and others travel through the Atmosphere for a random distance until they encounter another GHG molecule.
- Having emitted the energy, the molecules cool down.
DISCUSSION
As in the other postings in this series, only radiation effects are considered because they are the key to understanding the Atmospheric “Greenhouse Effect”. I recognize that other effects are as important, and perhaps more so, in the overall heat balance of the Earth. These include clouds which reflect much of the Sun’s radiation back out to Space, and which, due to negative feedback, counteract Global Warming. Other effects include convection (wind, thunderstorms, …), precipitation (rain, snow) and conduction that are responsible for transferring energy from the Surface to the Atmosphere. It is also important to note that the Atmospheric “Greenhouse Effect” and a physical greenhouse are similar in that they both limit the rate of thermal energy flowing out of the system, but the mechanisms by which heat is retained are different. A greenhouse works primarily by preventing absorbed heat from leaving the structure through convection, i.e. sensible heat transport. The greenhouse effect heats the earth because greenhouse gases absorb outgoing radiative energy and re-emit some of it back towards earth.
That said, how does this visualization help us understand the issue of “CO2 sensitivity” which is the additional warming of the Earth Surface due to an increase in atmospheric CO2? Well, given a greater density of CO2 (and H2O) molecules in the air, there is a greater chance that a given photon will get absorbed. Stated differently, a given photon will travel a shorter distance, on average, before being absorbed by a GHG molecule and be re-emitted in a random direction, including downwards towards the Surface. That will result in more energy being recycled back to the Surface, increasing average temperatures a bit.
Tim says:
What do you mean? The 168 W m-2 is directly from the sun, with almost no IR with energy in wavelengths LONGER than 4um. The 325 W m-2 is from the GHGs and clouds, with almost no energy in wavelengths SHORTER than 4 um. How could one be “included” in the other?
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Tim, I hope you have a good logical mind, especially when it comes to physics!
Follow me, remember that 1000 W hot plate mentioned above, if it were radiating against zero K? I can see that. 1000 W in, 1000 W out always and if the plate had ½ m² area on each side, a total of 1 m², it’s temperature would be the fourth power of 1000/5.67e-8 or 364.4 K as a black body (lets assume pure black and one for emissivity). If you were spraying water on the surface continually, just enough to carry away 200 W as latent heat, could that same surface also radiate 1000 W continually? To me, of course not. How about you? But that is exactly what thermal & evapo-transpiration energy transport is in the KT97 graphic is, like spraying water on a warm (288 K) surface, and through convection and evaporation carries 102 W/m2 away from the surface. So, can it also radiate 390 W/m2 in reality? I might have already tipped my hand. ☺
I want some time to properly answer that question with numbers but is has nothing to do with radiative bands for I accept the 168 W/m2 of solar being converted, by many methods, into IR that warms the surface. The 66 Wm-2 mentioned comes into play deeper but give me a while to answer that correctly. I already have more than one in the air.
Wayne says:
“If you were spraying water on the surface continually, just enough to carry away 200 W as latent heat, could that same surface also radiate 1000 W continually? To me, of course not. How about you? “
That much sounds perfect.
“But that is exactly what thermal & evapo-transpiration energy transport is in the KT97 graphic is”
Its not exactly the same. In your “running water” experiment, you never need to deal with the energy once it runs off into the bucket because that energy is “far from the box” and doesn’t send any appreciable energy back to the box. For the earth, the warm evaporated water is still “near the surface” and shares its energy back with the earth (in the form of IR radiation from clouds and GHGs). (Your experiment would be more like taking the evaporated water from the oceans and piping it off to Mars so we could get rid of the energy from the earth.)
If K&T numbers are right, this IR radiation from the atmosphere amounts to 324 W m-2 (this would be like taking the warm water you collected in your bucket and running it around your box so it could help warm the box). For the earth, this “back radiation” plus the 168 W m-2 from the sun is just enough to let the earth radiate upward AND drive evaporation AND create thermals.
I’m not sure I explained that really well, but you need to look at ALL the energy and where it goes. In a lab experiment, you can take the energy away easily and compartmentalize it. In the earth, the energy can only leave if 1) it reflects back out without ever getting absorbed or 2) radiates away as IR.
Wayne says:
“If you (or others reading here) ever want to do a simple loop accumulation using Planck’s equation instead of SB, the equation in Wikipedia is missing π in the numerator. ”
Note that at the top of the wikipedia page for Planck’s Law, it says
“This function represents the emitted power per unit area of emitting surface in the normal direction, per unit solid angle, per unit frequency. It is a specific radiative intensity.”
Since the energy can also go out at other angles, that is where the missing π is. You have the equation corrected to show energy in all directions, which is better if you want to integrate to get S-B Law.
wayne says:
A surface radiates according to its temperature. Whether other processes are carrying away heat is irrelevant. So yes, a 288 K surface of emissivity 1 radiates ~390 W/m^2.
Now, what is true is that the steady-state surface temperature is determined by the balance of the various heat transfers to and away from the surface. So, what would be true is that a surface that has a lot of heat transferred away by evaporation and convection will, all else being equal, equilibrate to a lower temperature than one that does not. So, in particular, if we “turned off” evaporation and convection in the atmosphere, what would happen is that the surface of the earth would heat up. In fact, if the other transfers to the surface don’t change (probably a rather naive assumption but let’s go with it), the surface would heat up to the temperature necessary for the radiative emission to equal what the sum of the radiative, convective, and evaporative transfers were before.
Joel Shore, you are right, the temperature would compensate. You can’t have, continually that is, energy removed from a surface by non-radiative processes and then calculate the radiation from the original temperature when ignoring the other exits of energy from that same surface.
But that means 305.2 K (32ºC or 89.7ºF) according to KT97, (390+102) W/m2 for the mean Earth surface temperature if you ignore the thermal and evapo-transpiration processes also cooling the surface. This is worse that I thought! (and more like smoke and mirrors). Each piece of information like you supplied helps.
Thanks Joel.
Wayne says:
April 13, 2011 at 4:04 pm
I’m not sure what you mean by portholes. Here is a quick drawing (take it as a very rough estimate of the experiment setup). To me you could even divide the measurements in separate runs. One, just measure the SW+LW with no cover at all. Next, just measure the amount of heat captured in the flowing water, no box. Well, that give youa close example of what was in my mind. In forty years of reading science of many branches I have never seen such an experiment performed, it raised my curiosity!
http://i52.tinypic.com/2u5qu5w.png
Thanks for the pic. I was actually imagining you began with a box without cover and then with glass and running water. The porthole referred to something in a link I thought I’d posted, put in the wrong URL, and now can’t find. It was just a page on the two ways of harnessing the Sun’s energy for heat; thermal doing what it says on the box, harnessing the heat energy direct, and photovoltaic the light energy to create electricity. It also mentioned on the page, and the correct term still escapes me, that light energy useful for illumination through special windows in the roof which can then be taken into room without direct access. The drawback, it said, was the loss of heat in the room through such. So, still calling them portholes.., and still thinking of what I thought you were describing.., I wondered if that would be a problem in measuring with lid on after lid off, that thermal energy would be escaping at the same time as the measurement was being made for the Light energy contribution minus thermal IR and that would have to be factored in. I wondered if beginning with a cold box with removable lid and all insulated from the midday sun for first measurement with, then exchanging lids to see rise in temp if any from shortwave Light, and I suppose then, without any lid to see difference if any.
one more thing. If one of my grandkinds ever need a really neat science project that one could kill two birds with one stone!
If you’ve got the funds for your grandkids experiments…, I’d really like to know if this is junk science… http://earth4greenenergy.com/TelsaFreeenergyGenerator.aspx
So, I wrote a display of these curves and if I use a log plot, I get basically what Joel showed above at http://wattsupwiththat.com/2011/03/29/visualizing-the-greenhouse-effect-molecules-and-photons/#comment-634439 from Colorado.edu, where as if I plot without the log compression, you get much closer to what this (http://i56tinypic.com/5wk13l.gif shows, much LW. So, it has a big difference if you plot a log compression. Alas, I’m still trying to figure out exactly what this means. .. If you look at the log compressed spectrum (Planck curve) it appears there is almost no LW in the sun’s spectrum, but.. but, Planck had already compensated for the fact that longer wavelengths carry less energy within his equation itself. See my point
I’m not sure what you mean by Planck’s compensating for the fact that longer wavelengths carry less energy within his equation itself. But, it seems to me, that the concept of energy is askew here somehow. To me, ignorant as I am of the maths, it simply looks like it shows peak of frequency, not volume of energy. It’s a measured fact as I’ve given before in the example of light bulbs and steel billets, that the amount of visible light is practically insignificant compared with the amount of thermal energy being emitted. I could find you the links if you haven’t seen them.
What, to me, is the problem here, is that AGW&others think this Planck peak energy is capable of itself producing a particular kind of energy, heat, but, since it is itself only the result of, an effect, of a massive amount of heat first being generated, and at the same time being radiated out all the while in greater amounts as the source becomes hot enough to produce this ‘peak’, it doesn’t mean that this peak is hot enough to do anything. That’s just an unwarranted assumption. High frequency doesn’t relate to, whatever the term is, ability to do work. I think there’s a disjunct between thinking highly energetic means ‘high energy intensity’, i.e. power. The amount of heat generated by a very hot source is a darn sight more powerful, you can feel it, than the piddling amount of red or white light being produced.
And, these high frequencies are tiny, they are easily scattered through the atmosphere off the nitrogen and oxygen molecules, quickly losing whatever ‘high energy’ they have. They can certainly be powerful when their intensity is concentrated, as in a laser, their tiny waves, as I imagine it, becoming like a high speed drill, but in themselves they are benign (as described on some page I linked to). Plants aren’t drilled full of hot holes when they take in Light… UV is the more powerful drill naturally on Earth, in intensity, such as on mountain tops etc., and unused to it in hot climates skin is easily burned – but one cannot feel it, in itself, UV isn’t hot, isn’t carrying heat – thermal IR is heat on the move from one place to another, it can cook the skin, but intense UV simply chars it, like starting a fire by rubbing sticks together. And, for example, IR is used in intensity, laser tracking/targetting, precisely because of its ability to get through cloud and atmospheric conditions intact, without being so easily bounced away by stuff.
There’s no real discernible ‘power’ in these high frequency, energetic states, they work on a different level, microscopic, cellular, while going into the thermal this becomes the size of a pin head of energy, palpable. Until this Planck thing is sorted, the belief that highly energetic equates to high power, there’s no “sense of scale” from AGW/others promoting the idea.
This is the same problem, I think, as with the AGWScience concept of CO2. Where CO2 is deemed to be an ideal gas regardless that no real gas is ever that, nor ever in the conditions for ideal gas, these laws are quoted as proof that CO2 can do the impossible things claimed for it, defying gravity etc. So, here, what is Planck or flat earth SB, actually saying here?
I really, really, need convincing better than the AGW/others arguing this way are managing, showing as they do no sense of properties, etc. To me the y axis scale isn’t in scale to the amount of energy being radiated by the Sun.
Which you then go into too in your next para. But, I think what you’re seeing as “overly emphasize the longest frequencies”, is actually more like the reality – 5% of a bog standard light bulb is emitted Light, 95% Heat.. Why should the Sun be any different? Except that it’s hotter and producing even more highly energetic waves into Gamma. But again, highly energetic does not equate to ‘power’. These are easily distracted from their course by one obstacle or another because they move so quickly, which is all high energy means. Doesn’t it?
Walla, I’m getting there but not quite finished with my analysis, you might just be close to the right answer, but, I do want you to admit that whatever small amount of SW that does in fact get absorbed does, in the end, may be a year leater, is converted to heat. See my point there? Photosynthesis will convert SW to matter (wood, plant matter), not heat, but years later that same chemical energy is, in the end, converted to heat (forest fires, decay). There is a lag in many cases and sometimes it is released a long, long time later. When looking at an energy budget it does seem this still needs to play in somewhere when looking over a long time and averaged.
But.., you’re thinking of REAL Science energy budgets. 🙂 Sometimes there’s discussions on the ‘missing energy’, my only contribution has been, Life using it. Doesn’t apply here. And that’s the problem. AGWScience has so skewed reality for its global warming that the only premise it has is that the Sun’s energy actually heats the Earth, land and sea, and that heated Earth then radiates out Thermal energy getting trapped in the supermolecule CO2 which is so powerful it forms an insulating blanket over the Earth slowing down the thermal IR escape from the Earth/back radiating and heating the Earth, whatever, and so raising the temperature globally ad infinitum. That it’s a trace gas etc. is sadly not appreciated because, as with using Planck and ideal gas scenarios, there’s no sense of scale or properties in their concepts; one dimensional flat earthers living in closed test tubes full of stuff that takes up no volume in empty space. If I could find a way to get CO2 to stay in an insulating blanket layer at the top of my room…, or in a sheet I could put infront of all my radiators which I’d then turn right down.., or maybe I should just breathe on them? That would warm me up.
Myrrh, hey, thanks. You were saying
“I wondered if that would be a problem in measuring with lid on after lid off, that thermal energy would be escaping at the same time as the measurement was being made for the Light energy contribution minus thermal IR and that would have to be factored in. ”
Yeah, you would have to factor every difference, measuring and cancelling when possible, to get the best accuracy from such a simple experiment.
And on Tesla, that’s interesting. When I was about fourteen I almost got a Tesla coil built, bought the wire, got the big tube, it’s still in the attic, but was never able to find an affordable 25kV neon transformer. Bummer. Along with proper science I always follow the latest neat and cool experiments like that, never know when someone might actually find something new under the next stone.
But back to your view of the incoming solar energy. You have made me look hard at that aspect and I think you are half right and half wrong (on the near IR), you’ve been misled by NASA’s statement about the T.V. controller. Now that I have a program that lets me type in any temperature and any range of wavelengths, I realized that you are wrong in thinking that near-IR doesn’t heat. I should have known that! For years I managed workers who worked with an industrial dryer on that very aspect.
It turns out that 1400 K is the temperature that is required to just start the emittance of soft orange light, but the visible wattage is very small. We just had a cold front come thru, so I had my little 300 W space heater on under my desk. Know what? It just barely reaches orange in color, mainly weak red but a tint of orange just coming in. Another, look inside your toaster. At 1400 K (hot nichrome wires) only ~1% is in the visible range but some 80% is in the near-IR range. That is what makes them so damn hot.
But on the visible side you have made me come over to your side. Since 31% of the solar is reflected (albedo), that is nearly totally in the visible range. Take the numbers I included in a comment to Joel above.
~63,200,000 * 31% = 19,592,000 W/m2 that is rejected from the Earth system in visible. But visible was ~27,700,000 W/m2 so get a ratio, 19,592,000/27,700,000 = 70%. That means about 70% of the visible energy is rejected from the system leaving little to convert, when absorbed, ~30% of the visible. Now that was a very rough estimate but you seem right in the end on that aspect, IR is the majority of the warming though in the near-IR range. In KT97 graphic that means 235/341 or 70% has to come from something other than visible and the numbers now make some real sense, it’s the near-IR. Thanks for your pernicious persistence!
I have learned much in the last two weeks outside this post. The numbers from Miskolczi and Trenberth and Kiehl are starting to converge in my mind but it only shows how terribly distorted the KT97 leaves you with and the many people who on one respect have a liking for science but don’t know just enough to reject the pseudo-science part.
In kT97 you find a figure of 324 W/m2 that they called “back radiation”…. not so, the arrow is actually pointing the other way, upward and just forget the 390 W/m2 arrow completely, that is just normal thermal resonance at the surace at 288K (the bottom few meters). You can extract that by Miskolczi’s figures on the global mean clear-sky IR optical thickness, or tau of 1.8675. Here’s how.
390 * (1-e^-1.8675) = 329.7 or very close to the 324 stated in the graphic.
Using TFK09 graphic you get:
396 * (1 – e^-1.8675) = 334.8, just 1.8 W/m2 off of the 333 stated.
The e^-1.8675 is the transmittance which does not get absorbed. The (1 – e^-1.8675) is the absorbance within the entire atmosphere, not “back radiation”.
In KT97 you also get what Miskolczi is speaking of as K being the thermals and evaporation/convection. F being the amount of the inbound solar radiation absorbed by the atmosphere. P is the internal energy but is only about 0.03% so is set to zero. KT97 is ((24+78) + 67 + 0 + (161-102)) = 235 W/m2 that is the OLR (outgoing LW radiation). The 102 is just the 24+78.
Same for TFK09 you get ((17+80) + 78 + 0 + (161-97) ) = 239 W/m2 of OLR. The 97 is just the 17+80 on the graphic.
Here is a quote from a letter answering KNMI’s questions on the Miskolczi Theory:
Titled: Miskolczi’s theory of a saturated or constant greenhouse effect.
I will add, nor is there a new animal to science called “backward radiation”.
Myrrh, you should search out some of the many “plain English” commentaries and articles thoroughly explaining his approach. I’m still learning something new each reading, and I’ve read them a few times each. It is deep at first but soon it will all start to make sense once you get used to the variable names. It is a fantastic piece of physics work. He has grown since 2004 a great deep understanding and is now applying this to the planets and I hope later the moons with atmospheres… that is what should have happened all along in the real “climate science”.
Wayne says:
“~63,200,000 * 31% = 19,592,000 W/m2 that is rejected from the Earth system in visible. But visible was ~27,700,000 W/m2 so get a ratio, 19,592,000/27,700,000 = 70%. That means about 70% of the visible energy is rejected from the system leaving little to convert, when absorbed, ~30% of the visible. ”
This is definitely on the right track! However, I think you are over-estimating the amount of visible reflected and underestimating the amount of IR reflected. In fact, IR from 0.7 to 3 um (the vast majority of IR from teh sun) is often called “reflected IR. It is quite easy to take photographs using this reflected IR, so it must reflect pretty well. As this graph shows, many common materials reflect IR BETTER than they reflect visible (http://www.penguinslab.com/Pictures/IRphotos/ir-refl.gif).
I don’t know the correct numbers, but I suspect that the answer is much closer to 30% reflected for visible & 30 % reflected for IR, rather than70% reflected for visible & 0% reflected for IR.
Tim says:
“This is definitely on the right track! However, I think you are over-estimating the amount of visible reflected and underestimating the amount of IR reflected. ”
Tim, you’re bound to be right to some degree. If you noticed I just lumped it all in those numbers, not finding any papers or data any closer. Was hoping someone else might read this and have better info. Also, you can see in that NIR ranges there are water, N2, and CO2 lines and bands so some NIR must also be absorbed the atmosphere itself making up that 67 W/m2 in the K&T diagram or the F parameter in Miskolczi’s calculations.
wayne says:
In a sense, you are correct. It is just a fact that things that have a temperature, including the atmosphere, radiate (solids and liquids across a broad continuous spectrum of wavelengths and gases at certain more discrete wavelengths that depend sensitively on the details of the molecule. The term “back radiation” is used colloquially to talk about the radiation from the atmosphere that is directed back at the earth because we tend to think of thermal IR radiation as mainly going from the earth back out into space (which is what it does in the net)…and when we look at the net effect of IR absorbing gases in the atmosphere, it is eventually to send some of this radiation back toward the earth.
I think the reason why many hardcore greenhouse effect skeptics have latched onto the term “back radiation” is that they’ve discovered that it is easy to bamboozle people into thinking this is some funky weird new thing that is unique to the greenhouse effect. In fact, it is just the colloquial term used in this particular context but really describing something that is basic and well-founded in radiative physics. Since “back radiation” seems to endow it with such an air of mystery, perhaps it is better not to use the term. Whether or not the term is used has absolutely no effect on any results that you get when you apply the very well-confirmed equations of radiative physics to the earth’s atmosphere.
Wayne – re your:
But back to your view of the incoming solar energy. You have made me look hard at that aspect and I think you half right and half wrong (on the near IR), you’ve been misled by NASA’s statement about the T.V. controller. Now that I have a program that lets me type in any temperature and any range of wavelengths, I realized that you are wrong in thinking that Near-IR doesn’t heat. I should have known that! for years I managed workers who worked with an industrial dryer on that very aspect.
Quick recap from my perspective. Near IR is not Thermal, Thermal is Heat. (I’ve noticed that AGWScience bias in explanations will often claim that it isn’t, as if Heat is only generated as a reaction, but pretending it ain’t doesn’t make it so – Thermal radiation is actual Heat on the move, it exists whether or not we feel it or something captures its heat.) It’s (Near IR), has never been catagorised in Science as Thermal. There is Heat and there is Light. That’s bog standard. It’s catagorised in with the short-wave as reflective, not penetrative. It’s microscopic, it is not hot.
Sure, it can “create” heat in some circumstance, all light can when it’s intensified, etc., and in some jobs, such as furnace workers, close encounter exposure to the near IR can have adverse health effects, but even there. It’s not the “heat” it generates it’s the chemical changes on a microscopic/cell level in the body (*). The very thing that it is used for in many healing applications can be detrimental in larger doses. NASA has explored its healing effects in some depth in looking to protect the physical well-being of its spacetravellers and near IR and thermal IR are now well documented and known for their different properties in the medical sciences and general healing areas. What began with a ‘let’s see what laser concentration intensity with light does in the body’, has found that changes in the body’s chemistry affecting healing don’t need concentrated laser intensity, because it’s the actual light itself which makes the changes, i.e., you could shine your key-ring light on a difficult to heal wound on your skin and you would see healing change. Effectiveness is dependent on distance, amount and time, and these are all relevent in the on-going exploration of what effects different wave-lengths have in the body. I’ve had near-IR used on me in dental care; it did not feel hot, it did not make my gum heat up, it was very close to the gum and the procedure took several long minutes (all minutes are longer in the dentist’s chair).
I don’t know what wavelength of ‘near IR’ was being used by these industrial dryers, but, as I gave above, in practical application near IR is deemed not thermal which begins at 1000nm. In healing science using LED, (sometimes called cold laser, though it’s not laser, but terms haven’t yet become standardised), near IR stops at that. As I previously discussed with Tim, I say that thermal IR becomes that when it becomes that at whichever wavelength it happens, because, there is a variety of cut-off points more often than not depending on the use to be made of particular wavelengths. However, there’s a general use where I haven’t seen it taken further, that near IR goes as far as 1.4um.
All this to set the scene to reply to … 🙂
It turns out that 1400 K is the temperature that is required to just start the emittance of soft orange light, but the visible wattage is very small. ..Another, look inside your toaster. At 1400 K (hot nichrome wires) only ~1% is in the visible range but some 80% is in the near-IR range. That is what makes them so damn hot.
Not what you are feeling if NASA is right, and my own experience of near IR is right, and all well known in the quite considerable real life uses in the medical science professions, because, near IR is not hot. You cannot feel it any more than you can feel visible light. In intensity or volume it may well also be able to have a heating effect, (but that effect will be minimal, you might find after some time of using large volumes of near IR or even the higher visible light energies that your skin begins to feel a little warm), but it is not heat, therefore, it is not Thermal IR.
Thermal energy, thermal IR is what you are feeling as heat from your toaster. Heat is thermal energy, which is thermal IR, on the move. Exactly as the NASA page describes, but will remove from teaching children from the end of May.
How much near IR is there really? As with the Sun, the hotter the object the more higher frequency energies it gives off. At some point then the toaster will change from emitting 100% thermal IR to 99.9 Thermal and .1% near IR, and so on into the Visible.
The heat we feel from a roaring fire in the grate which will burn us if we stand too close to it, is Thermal IR. That we see colour means that it is also emitting near IR, but, as with the dangers even to furnace workers, etc. and those in similar conditions for hours on end and daily, the danger is from some kind of chemical change because these shortwave lights at best in volume will cause only mild warming of the skin’s surface (you have to go into UV to get burning in normal conditions, and that is not even capable of penetrating through the first layer of skin, the epidermis).
So, in themselves near IR and the shortwave Visible and UV are not hot, therefore they are not the thermal wavelengths of IR which is actual heat. They are not that powerful, high energy of a wavelength does not equate to high power to effect large macro changes in matter. They have limited penetrative effects in organic matter, UV barely penetrates the surface of a body, Visible can penetrate a little further, and near IR further still, while thermal IR penetrates the deepest. That’s why we have near IR used in effecting chemical changes in the body in healing, and thermal IR in deep tissue healing. They have different properties, different characteristics. UV enables us to make a chemical change in the body to produce Vitamin D, no other light will do, for example. It is only Thermal IR which is capable, physically, of heating up the Earth from the direct energies of the Sun for all practical purposes.
So my gripe about the AGWScience Energy Budget. These energies are utterly physically incapable of doing what they say they do.
(Added to which, they claim it is Near IR, but have included further into the thermal range.., but that still would not be able to convert into the heat they say is heating the Earth to give off that amount of Thermal IR, as they’re still close to near IR, just another sleight of hand.)
But on the visible side you have made me come over to your side. …. Now that was a very rough estimate but you seem right in the end on that aspect, IR is the majority of the warming though in the near-IR range. In KT97 graphic that means 235/341 or 70% has to come from something other than visible and the numbers now make some real sense, it’s the near-IR. Thanks for your pernicious persistence!
🙂 Hoping to have convinced you to take another look….
NASA says that near IR is microscopic/cell size, and another link I posted said that Visible high energy bounces off oxygen and nitrogen molecules and so because of their small size and rapid movement this results in the scattering in the atmosphere which gives us blue sky, and although IR generally because of their longer wavelengths and growing bigger in size have more punch to get through even water vapour in our atmosphere (think fog), the near IR is still very small and so more easily reflected off things. Think near IR cameras (not thermal IR imagers) which picture the near IR reflected off objects just as Visible light bouncing off objects is why we can see them. In other words, I think your 70% is majority thermal IR.
What about, assuming for the moment that you end up agreeing with my explanation above, that near IR is not the heat you feel from your toaster, – how hot does the Earth have to get in KT97 to give off that amount of Thermal IR? If 95% of a sodium lightbulb is given off as Heat, Thermal IR, and only 5% Visible (which I suppose is actually also including the invisible Near IR, which is not hot..), your 70% seems about right for the Sun given that it’s producing other things. I’ve seen a figure of 80% for thermal IR from the Sun, and 60 something, but not with accompanying calculations.
(*) This page gives the different reactions that can happen when electromagnetic enter the body – http://www.pol-us.net/lllt/phototherapy.html
“When a photon is absorbed by a molecule, the electrons of that molecule are raised to a higher energy state. This excited molecule must lose its extra energy, and it can do this either by re-emitting a photon of longer wavelength (.e., lower energy than the absorbed photon) as fluorescence or phosphorescence, or it can lose energy by giving off heat, or it can lose energy by undergoing photochemisty. Photobiological responses are the result of photochemical and/or photophysical changes produced by the absorption of nonionizing radiation.”
If 95% of a sodium lightbulb is given off as Heat, Thermal IR, and only 5% Visible
Which it isn’t, it’s not an incandescent light, it’s mostly visible.
Mods, any comments on why my posts on here are being blocked?
[Comment: One post was in the spam folder. Now rescued & posted. There were no others. ~dbs, mod.]
“I think the reason why many hardcore greenhouse effect skeptics have latched onto the term “back radiation” is that they’ve discovered that it is easy to bamboozle people into thinking this is some funky weird new thing that is unique to the greenhouse effect.”
Bamboozle in what way??
It seems fairly clear to me. The GHG backradation theory means that (slayers ch 14)
certain trace gases in the atmosphere absorb and reemit infrared radiation. The component that is radiated downwards warms Earth’s surface more than would occur if only the direct sunlight were absorbed.
How do you think hardcore skeptics are trying to bamboozle people? Do you agree that it cause further warming not just a slower cooling rate?
“There is only radiation, there is no such separate thing as “backward radiation” or “back radiation” in reality, only radiation”.
Wayne. Thanks for these comments
I have since reread the slayers book. I will read your references above when time permits.
Phil – thanks, I meant incandescent, unlike sodium ..
..in thinking what happened I’ve recalled I got distracted while typing, meaning to write incandescent, which I was thinking of and the sentence had already formed in my mind, I wondered if the glass of these bulbs was made from the same kind of mix as yer bog standard glass windows, sodium part of this, and decided it probably was the same kind of sodium glass. The daft thing was that even in re-reading it before posting to check I only briefly hesitated, but didn’t follow through for sense since the spelling was OK 🙂
A p.s. to Wayne re Miskoczi – I will certainly. At the moment I’m pushed for time to concentrate on anything ‘new’ in depth, but from the end of April will have more free hours to spend exploring your links and onward.
..and re-reading my post I’ve noticed several typos I missed first time round, but the sense is still recoverable, I hope.
RJ says:
Bamboozled in exactly this way: What does “the component that is radiated downwards warms Earth’s surface more than would occur if only the direct sunlight were absorbed” mean? Temperature is not determined by considering only the radiant energy absorbed; you also have consider the radiant energy re-emitted.
If the claim is that the greenhouse theory predicts that the earth would be warmer than in the case when it absorbed radiation and did not emit any, that is clearly ridiculous! If the earth did that, it would continually heat up if this were the case and over millions of years, the entire planet would boil away.
That is a somewhat ill-defined question since I am not sure what your definition of “further warming” vs “slower cooling rate” is. However, I think by any reasonable definition, it is more proper to say that the greenhouse gases slow the cooling rate…or that they change the radiative balance between the sun, earth, and space. (In the steady-state, they don’t even really do that, since the earth adjusts its temperature to maintain a balance between energy in and out. Rather, what they do is allow it to support a higher temperature at it surface than it would in their absence, just as putting on a winter jacket allows your body to support a higher temperature than it would if you went out naked when it was 40 below and quickly froze to death.)
Another way to put it is that the flow of heat (i.e., the net energy flow) is always from the warmer earth surface to the colder atmosphere. So, by both those measures, it seems most correct to say that the greenhouse gases slow the cooling rate.
So, thanks, RJ. I think you have provided a crystal clear example of exactly how the authors of Slayers have bamboozled you. They got you to think that temperature of the earth’s surface was determined by the amount of energy absorbed from the sun and ignore the fact that it actually depends on the balance between absorption and emission. It therefore led you to make lots of completely erroneous conclusions!
Perhaps now, seeing how these authors are clearly out to deceive you, you will not take what they say as seriously as you have. That book ought to come with the same sort of disclaimer that astrological pseudoscience comes with, “For entertainment purposes only!”
OK, forget about AGWScience and visual and near- and far-IR for a moment.
I’ve got four identical, sealed metal boxes, well-spaced from each other and each sitting on its own wooden table. They are each plugged into the electrical mains with voltmeters and ampmeters to measure the wattage going into each. According to the meters, there is 1 KW of electrical power going into each box. Each one has the same voltage and amperage going in. I come back an hour later after temperatures have stabilized.
Do I have to tell you anything else before you can answer two questions? 1) Is each box warm to the touch? 2) If so, are they equally warm when I measure their outside temperatures with themometers? Please write down your answers -based on basic bog science- and then go on.
OK, the first box has an electrical nichrome heater in it. When I open a little window and look in, it is dark except for a faint reddish glow. Virtually all the electrical energy is being emitted as mid- to far-IR.
The second has a number of ordinary incandescent bulbs in it, that are about 5% efficient in turning electricity into visible light. When I open a little window and look in, I see a moderately bright yellowish-white light. Almost all the electrical energy is being emitted as near- to mid-IR.
The third has a number of compact fluorescent lights in it, that are about 25% efficient in turning electricity into visible light. When I open a little window and look in, I see a very bright white light. Almost all the electrical energy is being emitted as visible to mid-IR.
The fourth has a number of LED lights in it, that are about 55% efficient in turning electricity into visible light. When I open a little window and look in, I see an eye-popping bluish-white light. Almost all the electrical energy is being emitted as visible to near-IR.
If you agree that all the boxes are equally warm, then, it seems to me, you have to admit that 1 KW worth of radiation, no matter the spectrum, produces the same amount of heat when sealed in a metal box. Yes, even the bluish-white light of the LEDs generates as much thermal energy as the red glow of the heater.
If you do not agree the LED box is exactly as hot as the nichrome heater box, and both are taking in exactly 1KW of electrical energy, what happened to the electrical energy going into the LED box if it did not turn into thermal energy?
No Ira, I have no intention of forgetting it, nor that you continue to avoid answering.
Nor, that your distractions are also nonsense with the usual mix of assumptions and not including analysis of properties, or proportions, or really, anything that makes any logical sense – just as in the AGWScience Energy Budget, that, for example, “most of the energy is being emitted in near to mid IR” in incandescent bulbs. HEAT is THERMAL IR. NEAR IR is NOT HOT.
AGWScience has this amazing method, I’m really impressed, truly, of producting ‘experiments’ which supposedly prove what it says about something, but when looked at in more detail, and I’m not going to bother with your example, perhaps someone else here has an interest, show a complete breakdown of scientific reality.
For example, dry ice forming fog on a stage for effect – obviously this proves that Carbon Dioxide mixes in the atmosphere.. Heating a jar of Air and a jar of Carbon Dioxide – obviously this proves that Carbon Dioxide is nasty hot thing in the atmosphere..
Are you one of the ones detailed to churn these out? And the put-downs? Which are so readily believed by the gullible/trusting/without access to real science? Let’s see, reply to Carbon Dioxide being heavier than Air, much merriment and ‘then why isn’t there a layer of Carbon Dioxide at the bottom of our atmosphere? Dead Sea? Brownian motion to thoroughly mix CO2 in the atmosphere? You must have a lot of giggles …
Just answer my question, give me real science proof how these Solar energies convert to heat on reaching Earth and make it hot enough to emit that much Thermal IR, real Thermal IR..
..or admit they can’t.
And do get on with it.
The Crackpot Index from John Baez
A simple method for rating potentially revolutionary contributions to physics:
1) A -5 point starting credit.
2) 1 point for every statement that is widely agreed on to be false.
3) 2 points for every statement that is clearly vacuous.
4) 3 points for every statement that is logically inconsistent.
5) 5 points for each such statement that is adhered to despite careful correction.
6) 5 points for using a thought experiment that contradicts the results of a widely accepted real experiment.
15) 10 points for each statement along the lines of “I’m not good at math, but my theory is conceptually right, so all I need is for someone to express it in terms of equations”.
36) 40 points for claiming that when your theory is finally appreciated, present-day science will be seen for the sham it truly is.
Just sayin’ …
Solar visual light energies convert to heat in much the same way the bluish-white light from the LEDs in the sealed metal boxes convert to heat. Light cannot penetrate the metal walls, so it bounces around and is absorbed, bit by bit, by the metal, heating it. Solar light strikes the surface of the Earth, and some fraction is absorbed, heating the Earth, while some reflects back through the Atmosphere and out to Space.
Ira Glickstein, PhD says:
…..”I’ve got four identical, sealed metal boxes, well-spaced from each other and each sitting on its own wooden table. They are each plugged into the electrical mains with voltmeters and ampmeters to measure the wattage going into each. According to the meters, there is 1 KW of electrical power going into each box. Each one has the same voltage and amperage going in. I come back an hour later after temperatures have stabilized”……
Ian you have assumed the outcome of your “thought” experiment !
What does that prove?
With that kind of reasoning you could prove anything!
Are there any real experiments to back up your conclusions?
Its quite clear that for instance light energy converts to chemical energy in the case of photosynthesis.
This chemical energy can remain locked up for hundreds of millions of years in the case of fossil fuels.
It will remain there for even longer if the crackpot advocates of AGW have their way.
In the meantime for all lovers of “backradiation” this new study should provide interesting reading.
http://journals.ametsoc.org/doi/abs/10.1175/2011JCLI4210.1
“However, I think by any reasonable definition, it is more proper to say that the greenhouse gases slow the cooling rate…or that they change the radiative balance between the sun, earth, and space”
So you do not agree with Ira then.
“The greenhouse effect heats the earth because greenhouse gases absorb outgoing radiative energy and re-emit some of it back towards earth.”
This is similar to
“certain trace gases in the atmosphere absorb and reemit infrared radiation. The component that is radiated downwards warms Earth’s surface more than would occur if only the direct sunlight were absorbed.”
But completely different to slow the cooling rate.
RJ says: April 18, 2011 at 2:56 am
“Its quite clear that for instance light energy converts to chemical energy in the case of photosynthesis.
This chemical energy can remain locked up for hundreds of millions of years in the case of fossil fuels.”
True, it can remain locked up for millions of years, but very little of it does remain locked up. Plants absorb energy via photosynthesis as they grow, converting that EM energy into chemical energy. But plants also use that energy themselves to process chemicals they need; furthermore plants get eaten and decay, converting the chemical energy back into other forms (ultimately into thermal energy). There would only be a NET absorption of energy if there was a net sequestration of plant matter over the years.
Sure, there is a significant net growth during the spring & summer, but there is a net drop in the fall and winter. Year over year, the change is pretty small.
In fact, since we as a race are currently 1) digging up & burning stored chemical energy from plants and 2) chopping down and burning forests and replacing them with much smaller and lighter crops, I strongly suspect the net energy flow is more thermal energy (from burning fossil fuels & forests) rather than less thermal energy (from annual average NET plant growth).