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Can Infrared Radiation Warm the Atmosphere???

Discussion in 'Science & Technology' started by palerider, Jan 21, 2018.

  1. Lagboltz

    Lagboltz Well-Known Member

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    Nope. You said:
     
  2. palerider

    palerider Well-Known Member

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    And in your mind that looks like a blank space...if you want to see light waves cancelling out, you can see it happening on a soap bubble...imagine that...it actually happens in the real world.
     
  3. The Scotsman

    The Scotsman Well-Known Member

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    I think the issue here is that not even the scientists can definitively explain what effect CO2 has in terms of "global warming". Radiative forcing is a massively complex issue and to say that this gas or that cloud or that ocean current or this time of day or night does this or does that is just not possible based on where they are with understanding all the feedback mechanisms etc etc etc. You are right there is a lot of data cherry picked and quoted and and and. The issue is that there is no one data set or analytic tool or computer model that can bring all the data together because science still does not know what data to bring to the table and what to do with it once its there....I'm not even sure we have the computational power to attempt it yet.

    It really is still the wild west in terms of this whole cliamte debate and the issue is that more and more people are understanding less and less as the complexities become apparent. So if someone comes and tells you that thay have the answer then maybe best to adopt the attitude of de omnibus dubitandum...personally I think all that one can say with any degree of accuracy is that climate changes....why and how....who the fuck really knows...god maybe?
     
  4. PLC1

    PLC1 Moderator Staff Member

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    Carbon dioxide traps the outgoing long wave radiation. Without it, the Earth would be frozen because more radiation would be returned to space. That's just basic junior high school level physics.

    well, maybe high school.

    But, it 's pretty basic stuff.

    Here's a more in depth analysis:
     
  5. The Scotsman

    The Scotsman Well-Known Member

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    Good news now start to factor that one teensy factoid into the whole picture bearing in mind it also emits long wave radiation...
     
  6. PLC1

    PLC1 Moderator Staff Member

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    Hardly a "factoid." That CO2 blocks outgoing long wave radiation is what keeps the planet from being an ice ball. Without it, in fact, life as we know it could not exist at all. Carbon Dioxide and water are two very important compounds. Too much or too little, and we start to have serious problems.
     
  7. Lagboltz

    Lagboltz Well-Known Member

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    A complete explanation of how CO2 affects the atmosphere is given in
    https://history.aip.org/history/climate/simple.htm#L_0141

    Start with the paragraph that begins with "What happens to infrared radiation emitted by the Earth's surface?"
    That explanation is not meant to describe the entire complexity of the atmosphere, but it does tell how CO2 radiation works it's way up the atmosphere, and the ramifications at the top of the atmosphere where the IR radiation is is dissipated to space. Although the link is titled as a simple explanation, it does require a good attention span and reading for comprehension.
     
  8. palerider

    palerider Well-Known Member

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    exactly how does CO2 do this magic. At atmospheric pressures and temperatures, CO2 absorbs, and then either immediately emits the radiation it absorbed, or in the vast majority of cases, it loses the energy it absorbed via a collision with another molecule. In either event, CO2 does not "trap" anything...so do describe this magic by which you believe it does.

    Then you should be able to offer up a pretty plausible description of the mechanism in question.


    I
    looked at your link and didn't see any explanation as to how CO2 supposedly "traps" outgoing long wave...
     
  9. PLC1

    PLC1 Moderator Staff Member

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    Basic eighth grade level science.

    I copied your question, redacted the silly word "supposedly", and pasted it in Google. Here's your answer:
     
  10. palerider

    palerider Well-Known Member

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    Clearly you have less understanding than an 8th grader...your source says that the IR leaving the earth is "caught" by the "excess" CO2 in the air.. There is only one gas known to man that can absorb and actually retain energy at atmospheric pressures and temperatures...and it is not CO2...Water vapor holds that position...and it is due to its ability to change phases in the open atmosphere...CO2 can only absorb and hold energy it its liquid or solid form and then releases it when it changes phases...but alas, CO2 does not change phases in the open atmosphere...

    CO2 and all the other so called greenhouse gasses except for water vapor simply absorb and emit...or lose that energy by collisions with other molecules in the atmosphere..usually oxygen or nitrogen...

    Here is a conversation between a student and the man that most scientists believe to be the second most brilliant physicist on the planet (William Happer) regarding how energy moves through the atmosphere.

    From:David Burton
    Sent: Wednesday, November 12, 2014 10:49 PM
    To: William Happer
    Subject: Another dumb question from Dave

    Dear Prof. Happer,

    At your UNC lecture you told us many things which I had not known, but two of them were these:

    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? [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.]


    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.


    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)? [YES, ABSOLUTELY.]


    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? [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.]


    Here's an example from the NSF, with a lovely animated picture, which even illustrates the correct vibrational mode:

    Carbon Dioxide Absorbs and Re-emits Infrared Radiation | UCAR Center for Science Education

    [​IMG]

    Am I correct in thinking that illustration is wrong for about 99.9999999% of the photons which CO2 absorbs in the lower troposphere? [YES, THE PICTURE IS A BIT MISLEADING. IF THE CO2 MOLECULE IN AIR ABSORBS A RESONANT PHOTON, IT IS MUCH MORE LIKELY ( ON THE ORDER OF A BILLION TIMES MORE LIKELY) TO HEAT THE SURROUNDING AIR MOLECULES WITH THE ENERGY IT ACQUIRED FROM THE ABSORBED PHOTON, THAN TO RERADIATE A PHOTON AT THE SAME OR SOME DIFFERENT FREQUENCY. IF THE CO2 MOLECULE COULD RADIATE COMPLETELY WITH NO COLLISIONAL INTERRUPTIONS, THE LENGTH OF THE RADIATIVE PULSE WOULD BE THE DISTANCE LIGHT CAN TRAVEL IN THE RADIATIVE LIFETIME. SO THE PULSE IN THE NSF FIGURE SHOULD BE 300,000 KM LONG, FROM THE EARTH'S SURFACE TO WELL BEYOND A SATELLITE IN GEOSYNCHRONOUS ORBIT. THE RADIATED PULSE SHOULD CONTAIN 667 CM^{-1} *3 X 10^{10} CM S^{-1}*1 S WAVES OR ABOUT 2 TRILLION WAVES, NOT JUST A FEW AS IN THE FIGURE. A BIT OF POETIC LICENSE IS OK. I CERTAINLY PLEAD GUILTY TO USING SOME ON MY VIEWGRAPHS. BUT WE SHOULD NOT MAKE TRILLION-DOLLAR ECONOMIC DECISIONS WITHOUT MORE QUANTITATIVE CONSIDERATION OF THE PHYSICS.]


    (Aside: it doesn't really shock me that the NSF is wrong -- I previously caught them contradicting Archimedes: before & after.)

    If that NSF web page & illustration were right, then the amount of IR emitted by CO2 or H2O vapor in the atmosphere would depend heavily on how much IR it received and absorbed. If more IR was emitted from the ground, then more IR would be re-emitted by the CO2 and H2O molecules, back toward the ground. But I think that must be wrong.[YES, THE AMOUNT OF RADIATION EMITTED BY GREENHOUSE MOLECULES DEPENDS ALMOST ENTIRELY ON THEIR TEMPERATURE. THE PERTRUBATION BY RADIATION COMING FROM THE GROUND OR OUTER SPACE IS NEGLIGIBLE. CO2 LASER BUILDERS GO OUT OF THEIR WAY WITH CUNNING DISCHARE PHYSICS TO GET THE CO2 MOLECULES OUT OF THERMAL EQUILIBRIUM SO THEY CAN AMPLIFY RADIATION.]


    If 99.9999999% of the IR absorbed by atmospheric CO2 is converted by molecular collisions into heat, that seems to imply that the amount of ~15 micron IR emitted by atmospheric CO2 depends only on the atmosphere's temperature (and CO2 partial pressure), not on how the air got to that temperature. [YES, I COULD HAVE SAVED A COMMENT BY READING FURTHER.] Whether the ground is very cold and emits little IR, or very warm and emits lots of IR, will not affect the amount of IR emitted by the CO2 in the adjacent atmosphere (except by affecting the temperature of that air). Is that correct? [YES, PRECISELY. WE HAVE BEEN TALKING ABOUT WHAT CHANDRASEKHAR CALLS AN “ABSORBING ATMOSPHERE” AS OPPOSED TO A “SCATTERING ATMOSPHERE.” ASTROPHYSICISTS ARE OFTEN MORE INTERESTED IN SCATTERING ATMOSPHERES, LIKE THE INTERIOR OF THE SUN. THE BLUE SKY DURING A CLEAR DAY IS AN EXAMPLE OF SCATTERING ATMOSPHERE. VERY LITTLE HEATING OR COOLING OF THE AIR OCCURS WITH THIS “RAYLEIGH SCATTERING.”]


    Thank you for educating a dumb old computer scientist like me! [YOU ARE HARDLY DUMB. YOU GET AN A+ FOR THIS RECITATION SESSION ON RADIATIVE TRANSFER. ]


    So...CO2, at atmospheric temperatures and pressures simply absorbs and very occasionally emits a bit of IR but in almost every instance, absorbs IR and then promptly loses that energy via collision with another molecule before it can be radiated away.

    And again...refer to the OP...those engineers who are in the business of radiative heating are repeating over and over that IR does not warm the air...IR can only warm objects...do you think the IR coming from an infrared heater is somehow different from the IR emitting from the surface of the earth? Don't you think that they would know if IR were capable of heating the air...after all, infrared, and what it does, and does not do is how they make their living...it is the subject of their study...and none of them have ever seen infrared warm the air.

    That being said, you can certainly change my mind by showing me some real, observed, measured data which establishes a coherent relationship between the absorption of IR by a gas and warming in the atmosphere...got any?

    Of course you don't because there is none.

    Maybe if you worked on getting smarter than an 8th grader, you might not be such an easy dupe.
     
  11. Lagboltz

    Lagboltz Well-Known Member

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    Mr Pale, my BFF, we need quantum mechanics to answer all your questions. We really do. But you don't believe quantum mechanics. You said it is fantasy. We need to answer your questions using the idea of photons. But you don't believe that either. This whole area was covered before. You want to get into that quagmire again so you can causticly belittle every person and idea that disagrees with you?

     
  12. PLC1

    PLC1 Moderator Staff Member

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    Bullshit and insults are all you have.

    Radiative heating, i.e., long wave infrared, does indeed warm objects just as your source says. The Earth, in case you hadn't noticed, is an object. Some of that heat is radiated back into space, of course. Were it not so, then the Earth would be too hot to support life. It isn't. If all of the infrared radiation were to be lost back into space, then that object that is the Earth would be a ball of ice. In case you hadn't noticed, it isn't.

    Well, maybe you can find some site that claims it is, but no....
     
  13. palerider

    palerider Well-Known Member

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    Sorry but radiation from the cooler atmosphere does not warm the earth, except in rare instances of temperature inversion where the air is warmer than the earth. But if you believe it happens, then by all means show me a measurement of energy returning to the surface of the earth made with an instrument that is not cooled to a temperature lower than that of the atmosphere....

    Of course you won't be able to because energy does not move from cool to warm. Interesting, isn't it that we have no problem measuring energy leaving the surface with instruments that are not cooled and yet, the energy you claim returns to the surface can't be measured unless the instrument is cooled to around -80 degrees which is about the radiating temperature of CO2. ..you were aware of that weren't you? No? The primary radiating frequency of CO2 is 15 microns which is equivalent to about -80 degrees...you believe that a molecule radiating at -80 degrees is warming anything above -80 degrees?

    And again...radiation is barely a bit player in the movement of energy from the surface of the earth to the top of the troposphere...The energy absorbed by CO2 is almost always lost via collision with other molecules...it is conduction that warms the air...not infrared radiation...again, look to the literally millions of hours of observation and industrial use that demonstrates conclusively that IR does not warm the air.

    Water vapor is able to hold on to some energy as a result of its ability to change phases at atmospheric temperatures and pressures...a water molecule will absorb energy in the process of changing phases, for example, from liquid to vapor. That energy is held until such time as it changes phases again..say to ice when it has reached the upper atmosphere...at the time it changes phases from vapor to ice, it releases exactly as much energy as it required to change from liquid to vapor. ..being in the upper atmosphere, that energy is then radiated on out to space.


    Of course it is true...IR does not warm the air...again, feel free to provide a single measurement that establishes a coherent relationship between the absorption of IR by a gas and warming in the atmosphere. Like that single piece of observed, measured data that supports the AGW hypothesis over natural variability that I am always asking for, you won't be able to produce this one either...because there is no coherent relationship between the absorption of IR by a gas and warming in the atmosphere.
     
  14. palerider

    palerider Well-Known Member

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    So what you are saying is that observation, and actual measurement supports my position and unobservable, unmeasurable, untestable models are all you have in support of yours.. Yeah..that is what I have been saying all along.

    And again...IR does not, will not, and can not warm the air...millions of hours of observation and industrial application prove this to be true.
     
  15. palerider

    palerider Well-Known Member

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    If conduction rules the transport of energy from the surface to the upper troposphere...and IR can not warm the air...where, exactly does that leave the radiative greenhouse effect that you so fervently believe in?
     
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