Saturday, September 19, 2015

Why 'greenhouse gases' don't 'trap heat' in the atmosphere

Optical and electronic engineer KevinK, a frequent contributor to the Hockey Schtick, posted an excellent comment a couple days ago on the WUWT post How Reliable are the Climate Models, and with which I fully agree, and have elevated to a post here. 

KevinK elegantly explains why the Arrhenius radiative greenhouse effect essential to the theory of catastrophic anthropogenic global warming (CAGW) is fictional, and confuses the actual cause (the 33C gravito-thermal greenhouse effect of Maxwell, Clausius, Carnot, Boltzmann, Feynman, US Standard Atmosphere, the HS greenhouse equation, et al) with the effect (IR absorption and emission from IR-active 'greenhouse gases'). 





Mike Jonas writes:
“Carbon Dioxide (CO2) : At last we come to something which is quite well understood. The ability of CO2 to absorb and re-emit a specific part of the light spectrum is well understood and well quantified, supported by a multitude of laboratory experiments.
Yes indeed this is not in doubt. However, the result of this phenomenon in the climate is still very much in doubt. Especially with regard to the “average” temperature. Aside from the fact that an “average temperature” has no useful meaning. I’m reminded of the old observation that if one of your feet is in ice water and the other is in boiling water you are “on average” quite comfortable overall.
Here is where the alleged “GHE” breaks down. There are numerous examples of human designed optical systems (aka applied radiation physics) that exhibit “back radiation”. Including the optical integrating sphere and the multi layer optical interference filter. In both cases “back radiation” certainly exists, but it can be difficult to measure. In neither case does the “back radiation” alone cause the source to “reach a higher temperature”.
In the specific case of an optical integrating sphere the interior surface of the sphere (highly reflective) becomes a “virtual light source”. This concept of a virtual source is somewhat specific to the optical engineering community. It helps with understanding (and predicting) the paths that photons will follow through a system. However (and this is a very big however) it DOES NOT predict the energy present at any point in the system.
In the case of an optical integrating sphere with an incandescent filament (aka a light bulb) inside this “back radiation” merely delays the elapsed travel time of the photons flowing through the system. This is a result of the photons “bouncing back and forth” inside the sphere until they find an “exit port”.
This is known as the “transient response” of an optical integrating sphere. 
This is a somewhat obscure but still well understood concept. If you inject an input “pulse” of light (off, then quickly on, then quickly off again) this transient response function will create a “stretched” pulse of output light. Specifically this square input pulse is no longer a square output pulse since some photons will quickly find an exit port and others will “bounce near and far” before exiting the sphere.
The gaseous atmosphere of the Earth is quite like an optical integrating sphere in this regard. The photons arriving from the Sun and being converted to emitted IR radiation (still a form of light or electromagnetic radiation and following all of the same rules/laws) simply bounce “back and forth” between the atmosphere and the surface. All this bouncing merely delays the flow of energy through the system as the energy alternates between light energy and thermal energy.
Given the dimensions of the atmosphere (about 5 miles high) and the velocity of light (still considered quite speedy) this alleged “GHE” merely delays the flow of energy (arriving as sunlight) through the system by a few tens of milliseconds. The specific delay for any given photon is of course described by a statistical distribution.
Since the period of the arriving light is about 24 hours this delay of a few tens of milliseconds has no effect on the “average temperature” at the surface of the Earth.
Another example of “back radiation” and its practical uses is the multi layer optical interference coating. This is the highly engineered coating on most modern optical lenses. It appears slightly purple when observed off-axis. The purpose of this coating is to reduce reflections from the surface of a lens.
These coatings have greatly improved the quality of photographs and videos by increasing contrast and reducing “ghost images” (images that are created by the individual surfaces inside a modern optical lens).
These coatings function by delaying “following photons” by a time equivalent to a fraction of the wavelength of the arriving light. By creating exactly the correct delay interval the reflected light is exactly “out of phase” from the arriving light and destructive optical interference occurs. This moves the optical energy to a location inside the optical lens where it is no longer subject to surface reflections.
Both of these “applied radiation physics” effects/techniques have been applied for decades and are quite well understood.
The alleged “radiative greenhouse effect” merely delays the flow of energy through the system and has no effect on the “average temperature”. It does change the response time of the gases in the climate. Since the gases have the smallest thermal capacity of all the components present (Oceans, land masses, atmosphere) the idea that they are controlling the “average temperature” is quite ludicrous.
Modeling these radiative effects in the climate is probably impossible. The required spatial distances are sub-micron the the time steps necessary are in the nanosecond range. There would need to be a increase of computing power of about ten orders of magnitude to even begin to attempt this.
There is of course a gravitational greenhouse effect whereby the effects of gravity acting on the gases in the atmosphere of the Earth predict quite well (see the US standard atmosphere model last updated in 1976) the temperature of the atmosphere of the Earth with no use of radiative effects at all.
It is quite sad that all this effort has been wasted on modeling the “unmodelable”.
Cheers, KevinK.

    • Bubba, thank you.
      I did submit a somewhat whimsical explanation of this delay line effect to Anthony several years ago.
      I have submitted a more detailed explanation to other climate science sites as well.
      The “radiative greenhouse effect” is merely a form of hybrid optical/thermal delay line. It has no effect on the “average” temperature at the surface of the Earth.
      Cheers, KevinK
    • KevinK – Your comment is at a greater level of detail than my article, so as suggested would be better as a separate article. I note your “Since the gases have the smallest thermal capacity of all the components present (Oceans, land masses, atmosphere) the idea that they are controlling the “average temperature” is quite ludicrous.“, but to my mind the GHG theory whereby some outgoing IR is in effect turned back and thus affects surface temperature is at least prima facie credible [HS Comment: No, that's not credible, radiation from cold blackbodies cannot ever warm/increase the temperature/frequency/energy of hotter blackbodies, ever, proven by Planck's Law of Blackbody Radiation and Quantum theory]. I’m prepared to work with this version (even though, just like everything else, science may one day overturn it) while there are such glaring errors elsewhere.
  • KevinK,
    I think that is the best comment I have read here in several weeks at least. (a high complement considering the quality of the comments here)
    I do hope that you will offer that comment as a post, that it is posted, and that then the moderation allow a full and complete debate on all parts of it. There are many of us who think the mass of the atmosphere along with gravity is the main reason for the misnamed “green house effect” along with H2O in all its phases.
    ~ Mark
    • The thermal capacity of water is much greater than CO2.
      This is why the main purpose of indoor air conditioning is to remove the water vapor first and then secondarily reduce the temperature of the now dryer air.
    • Kevin, Liquid water yes, because of it’s much greater density. However the difference between water in the vapor stage and CO2 is much, much smaller.
      Regardless, the warming affect of water occurs even when it is the air aloft that is damp and the air at the surface is dry. IE, clouds.
      [HS comment: No many papers prove the net effect of clouds is cooling, although they can reduce convective cooling somewhat, but which has nothing to do with radiative forcing. In addition, increased water vapor increases the heat capacity Cp of the atmosphere, which decreases the lapse rate, which COOLs the surface].
  • Has anyone calculated the average delay for a photon that is within one of CO2 absorbtion bands?
    I strongly suspect that it is more than a few milliseconds. Given that the direction of the photon when it is re-emitted is random, it could be down as easily as up, if it is sideways, it will have many miles of dense atmosphere to traverse compared to up.
    • At about 22 minutes, Dr. Happer shows the “xylophone effect” on a CO2 molecule.https://youtu.be/gMdYmAo08O4
      Here is an email exchange between Dave Burton and Will Happer concerning the issue of “re-emitting” a photon v. collisions with other molecules in the air, mostly N2 of course:
      A portion of their discussion:
      After hearing Will’s lecture, Dave asks:
      1. At low altitudes, the mean time between molecular collisions, through which an excited CO2 molecule can transfer its energy to another gas molecule (usually N2) is on the order of 1 nanosecond.
      2. The mean decay time for an excited CO2 molecule to emit an IR photon is on the order of 1 second (a billion times as long).
      Did I understand that correctly?
      Will replies: [YES, PRECISELY. I ATTACH A PAPER ON RADIATIVE LIFETIMES OF CO2 FROM THE CO2 LASER COMMUNITY. YOU SHOULD LOOK AT THE BENDING-MODE TRANSITIONS, FOR EXAMPLE, 010 – 000. AS I THINK I MAY HAVE INDICATED ON SLIDE 24, THE RADIATIVE DECAY RATES FOR THE BENDING MODE ALSO DEPEND ON VIBRATION AND ROTATIONAL QUANTUM NUMBERS, AND THEY CAN BE A FEW ORDERS OF MAGNITUDE SLOWER THAN 1 S^{-1} FOR HIGHER EXCITED STATES. THIS IS BECAUSE OF SMALL MATRIX ELEMENTS FOR THE TRANSITION MOMENTS.]
      Dave: You didn’t mention it, but I assume H2O molecules have a similar decay time to emit an IR photon. Is that right, too?
      [YES. I CAN’T IMMEDIATELY FIND A SIMILAR PAPER TO THE ONE I ATTACHED ABOUT CO2, BUT THESE TRANSITIONS HAVE BEEN CAREFULLY STUDIED IN CONNECTION WITH INTERSTELLAR MASERS. I ATTACH SOME NICE VIEWGRAPHS THAT SUMMARIZE THE ISSUES, A FEW OF WHICH TOUCH ON H2O, ONE OF THE IMPORTANT INTERSTELLAR MOLECULES. ALAS, THE SLIDES DO NOT INCLUDE A TABLE OF LIFETIMES. BUT YOU SHOULD BE ABLE TO TRACK THEM DOWN FROM REFERENCES ON THE VIEWGRAPHS IF YOU LIKE. ROUGHLY SPEAKING, THE RADIATIVE LIFETIMES OF ELECTRIC DIPOLE MOMENTS SCALE AS THE CUBE OF THE WAVELENTH AND INVERSELY AS THE SQUARE OF THE ELECTRIC DIPOLE MATRIX ELEMENT (FROM BASIC QUANTUM MECHANICS) SO IF AN ATOM HAS A RADIATIVE LIFETIME OF 16 NSEC AT A WAVELENGTH OF 0.6 MIRONS (SODIUM), A CO2 BENDING MODE TRANSITION, WITH A WAVELENGTH OF 15 MICRONS AND ABOUT 1/30 THE MATRIX ELEMENT SHOULD HAVE A LIFETIME OF ORDER 16 (30)^2 (15/.6)^3 NS = 0.2 S.
      Dave: So, after a CO2 (or H2O) molecule absorbs a 15 micron IR photon, about 99.9999999% of the time it will give up its energy by collision with another gas molecule, not by re-emission of another photon. Is that true (assuming that I counted the right number of nines)?
      Will: [YES, ABSOLUTELY.]
      Dave: In other words, the very widely repeated description of GHG molecules absorbing infrared photons and then re-emitting them in random directions is only correct for about one absorbed photon in a billion. True?
      Will: [YES, IT IS THIS EXTREME SLOWNESS OF RADIATIVE DECAY RATES THAT ALLOWS THE CO2 MOLECULES IN THE ATMOSPHERE TO HAVE VERY NEARLY THE SAME VIBRATION-ROTATION TEMPERATURE OF THE LOCAL AIR MOLECULES.]
    • HS comment: Whether the true delay is microseconds to minutes makes little difference, since a 12 hour night can easily erase & reverse this "radiative heat trapping," with no net effect on a daily, annual, or multi-decadal basis whatsoever. 
  • There can only be one and only one 33C greenhouse effect: 1) the 33C Arrhenius radiative GHE, or 2) the 33C Maxwell et al gravito-thermal GHE, otherwise the greenhouse effect would be double (66C) that observed. Clearly, overwhelming evidence, such as the above, favors the gravito-thermal GHE by lightyears. 

9 comments:

  1. See here:

    http://www.newclimatemodel.com/greenhouse-confusion-resolved/

    published July 16th 2008 which said inter alia:

    "A warming effect in the atmosphere arises because between coming in and going out the radiant energy is ‘processed’ by the molecules in the atmosphere into heat energy and then back again, often many times for a single parcel of radiant energy, the number of times being directly proportionate to the density of the atmosphere. It is the density, not the composition which gives more or less opportunities for such collisions between radiant energy and molecules whilst the incoming and outgoing radiant energy is negotiating the atmosphere. When an atmospheric molecule absorbs radiant energy it vibrates faster thereby becoming warmer. It is momentarily warmer than the surrounding molecules so it releases the radiant energy again almost immediately. The speed of release is again dictated by overall atmospheric density because greater density renders it less likely that the neighbouring molecules are cool enough for a release of radiant energy to occur. However the time scales remain miniscule on the level of an individual molecule BUT on a planetary scale they become highly significant and build up to a measurable delay between arrival of solar radiant energy and it’s release to space.

    It is that interruption in the flow of radiant energy in and out which gives rise to a warming effect. The warming effect is a single persistent phenomenon linked to the density of the atmosphere and not the composition. Once the appropriate planetary temperature increase has been set by the delay in transmission through the atmosphere then equilibrium is restored between radiant energy in and radiant energy out."

    I would add that the thermal energy in the atmosphere is a consequence of conduction and convection from an irradiated surface beneath the atmosphere and NOT from interception of outgoing IR by GHGs.

    The fact is that as one descends deeper into the mass of an atmosphere then collisional activity gradually takes over from photon emission and the temperature rises accordingly.

    The lapse rate gradient follows the changing balance between collisional activity and photon emission with changing height above irradiated surface.

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    1. "I would add that the thermal energy in the atmosphere is a consequence of conduction and convection from an irradiated surface beneath the atmosphere and NOT from interception of outgoing IR by GHGs."

      Exactly. The Arrhenius-believers have confused the cause (gravito-thermal) with the effect (IR absorption/emission from IR active 'greenhouse gases').

      Not only that, the ONE BILLION TIMEs more likely, according to Prof. Happer above, transfer of energy by collisions with N2/O2 than emission of photons *accelerates* convective cooling of the troposphere.

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  2. I think I should clarify these words in that 7 year old article since subsequent discussions with AGW proponents over the years have shown that such clarification is helpful:

    " It is momentarily warmer than the surrounding molecules so it releases the radiant energy again almost immediately. The speed of release is again dictated by overall atmospheric density because greater density renders it less likely that the neighbouring molecules are cool enough for a release of radiant energy to occur."

    When referring to a release of radiant energy I mean that the absorbed radiant energy is transferred by conduction to surrounding molecules rather than via the release of a photon.

    Hence greater density allows the surrounding molecules to take more energy via conduction so that photon release becomes less likely.

    If density were lower and the surrounding molecules cooler then less energy would be transferred by conduction as opposed to photon emission.

    The relevant point is that mass density alters the ratio between conduction and photon emission at any given temperature.

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  3. My understanding is that the 15um frequency only happens at -80C? If so that's fairly high in the atmosphere where air is less dense.
    So point 1 is that stopping high altitude air at -80C getting colder isn't going to warm the surface at all.
    Point 2 is that the temperature of air full of radiant energy is still governed by the kinetic energy of the molecules. For example the top of Everest on a sunny day is still very cold, even though it receives a lot of short wave radiation. Therefore the amount of radiant energy in the air has no effect on temperature at all.

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    1. Due to the molecular structure of CO2, the bending mode transitions only occur and 15 ┬Ám. If CO2 was an actual black body (climate scientists falsely assume it is) the equivalent black body temperature is 193K or -80C by Wein's law for 15 um radiation. CO2 only absorbs/emits at 15um regardless of the surrounding kinetic temperature of the atmosphere.

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  4. That's what I understood. According to http://www.srh.noaa.gov/jetstream/atmos/atmprofile.htm -80C only occurs either side of the Mesopause between 80 and 95 km high. So how can any warming there affect ground level temperatures? We know there is no hotspot so is this not a fairly hefty box of nails in the CO2 warmist coffin?

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    1. Sure it just one of many unphysical assumptions that have nailed that coffin shut really since the Poisson Relation in 1823, but are so inconvenient that the warmists simply ignore them and move on with their religion.

      The US Standard Atmosphere shows that the atmosphere 0-100km is at a minimum temperature of 200K in the tropopause, thus the kinetic temperature of the atmosphere greatly exceeds the equivalent blackbody emitting temperature of 15 micron CO2 absorption/emission at 193K everywhere from 0-100+km!

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    2. typo should say "The US Standard Atmosphere shows that the atmosphere 0-100km is at a minimum temperature of 220K in the tropopause

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  5. I would have thought that the amount of radiant energy in the air has no effect on temperature?

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