måndag 7 januari 2013

Fiction of GHE 3: Infrared Thermometer

The CO2 global warming alarm is based on the idea of substantial absorption/emission of the atmospheric trace gas CO2 around a wavenumber of 667, supposedly changing the energy balance of the Earth + atmosphere according the following radiance spectrum presented on WUWT as Visualizing the Greenhouse Effect: Emission Spectra, with the ditch around 667 the overwhelming visual evidence of major impact:



The evidence comes from the Nimbus 4 Michelson interferometer/infrared thermometer viewing the atmosphere from above and recording a temperature of 220 K of outgoing radiation around wavenumber 667, which is attributed to the presence of the trace gas CO2 at the tropopause.

But is it possible that the trace gas CO2 can have such a major impact on the radiation balance of the Earth? Is the ditch in the radiance spectrum reality or fiction? How is the radiance spectrum constructed?  By directly measuring the radiance of different frequencies?

No, it is constructed from measurements of temperature according to Planck's law of radiation assuming an emissivity = 1. This is because the Nimbus 4 infrared thermometer measures temperature and not radiance, and the emissivity is not measured.

An infrared thermometer is in principle a blackbody BB which can measure the temperature of a given object O through radiative equilibrium at distance, as illustrated below in analog situation with two communicating vessels with the water level representing temperature: The level/temperature of O can be measured at distance by the reference BB through equilibration, while the widths of the vessels represent different emissivities. Evidently the wide vessel has much greater capacity of delivering water than the narrow vessel, thus has a much bigger (potential) emissivity, as indicated by the red arrows.
We thus understand that an infrared thermometer can measure the temperature of an object at distance without knowing the emissivity of the object. This is what makes an infrared thermometer so useful, because the emissivity of an object cannot be measured by temperature equilibration.

The Nimbus 4 infrared thermometer thus reports the temperature as function of wavenumber with in particular a temperature of 220 K from the presence of the trace gas CO2 in the tropopause, from which the above radiance spectrum is constructed according to Planck's law assuming emissivity = 1.

But is the emissivity of atmospheric CO2 = 1? No, it is not: Nasif Nahle computes using experimental data by Hottel and Leckner, presented in many books on heat transfer, that the emissivity of atmospheric CO2 is less than 0.002, thus very small.

But this means that the above radiance spectrum presented as the visual evidence of the greenhouse effect, is misleading. The ditch appears to be fiction.

23 kommentarer:

  1. Here is an explanation why Nasif Nahle is completely off with his computation.

    Explanation

    So that the emissivity is less than 0.002 is not true.

    SvaraRadera
  2. So you mean the emissivity = 1?

    SvaraRadera
  3. How on earth can you interpret the sentence,

    "So that the emissivity is less than 0.002 is not true."

    to mean that it is suggested that it is equal to one??

    Did you actually read what was written in the link?

    SvaraRadera
  4. I asked the question if it is not 0.0002, then what is it?

    SvaraRadera
  5. Think and search yourself...

    SvaraRadera
  6. Many instruments, using these "fictional" techniques, accurately measure climate values.

    - They measure SST - accurately compared with the temperature measurements in the ocean. They do it with different instruments at widely different wavelengths (infrared & microwave).

    - They measure the lower tropospheric and upper tropospheric atmospheric temperature - accurately compared with radiosondes.

    - They measure humidity - accurately compared with radiosondes.

    How do these instruments, using a fictional theory of physics, get the correct answer?

    And why do these radiometers on satellites measure much lower values of radiance at 667cm^-1 compared with 1000cm^-1 (from upward radiance)?

    When you take a surface radiometer and point it up at the sky in for example, the very dry cold Antarctic it measures much higher value of radiance at 667cm^-1 compared with 1000cm^-1.

    Does a radiometer measure something of value? Or not? What is your theory to explain these measurements?

    Please explain the spectral measurements in Atmospheric Radiation and the “Greenhouse” Effect - Part Ten – spectral measurements of radiation from the surface looking up, and from 20km up looking down, in a variety of locations.

    Claiming the measurements are all invalid because you don't believe in photons is nice.

    Explaining the measurements via a theory would be a "small step" forward.

    SvaraRadera
  7. The emissivity can be calculated from:

    1. Absorptivity,a = emissivity, e at the same wavelength (from Kirchhoff)

    2. Absorptivity is experimentally shown to follow the Beer-Lambert law, with a=1-exp(-tau) - wavelength dependent formula

    3. tau = sigma x N x d - again found from experiment
    where sigma = capture cross section of the molecule at that wavelength in cm^2, N = molecules/cm^3, d = path length in cm

    4. sigma = S.f(v-v0), where S = line strength, and f(v-v0) is the line shape as a function of wavenumber v centered on v0, integral of f.dv = 1, and the formula in the troposphere is Lorenzian with the half width of the line = [measured line half-width at p0,T0] x p/p0 x (T0/T)^n where n is also a measured parameter, typically around 0.5.

    The values of line strength, S (and n) at each wavenumber are experimentally determined and journals like Journal of Quantitative Spectroscopy & Radiative Transfer have published 100's of papers with these values. For example, The HITRAN 2008 molecular spectroscopic database, by L.S. Rothman et al, 2009.

    However, you should let your audience know whether you think these journals are writing fiction.

    Is there such a thing as absorption and emission of photons? What on earth are the instruments measuring? Why do higher concentration of gases result in darker absorption lines at certain wavenumbers? Why do the absorption lines get narrower at lower pressures?

    If the journals are correct - **please tell us** - then it is easy to show how the value of emissivity is calculated for, say, CO2, for a given pressure, temperature and thickness of atmosphere.

    Some results are shown in Visualizing Atmospheric Radiation where strangely, the calculated results using the HITRAN database and the above formula produce up and down radiance very similar to samples of measurements of radiance from FT-IRs.

    SvaraRadera
  8. I say that you can measure temperature by radiative equilibrium and net detector input by recording a transient, but not gross detector input because that requires knowledge of gross detector output, which cannot be measured and thus has to be fabricated e.g. using a false Planck law, and that is fiction or fraud depending on your mood.

    SvaraRadera
  9. The basic misconception is to believe that there is a two-way heat transfer version of Planck's law, with net transfer as the difference between two gross transfers back and forth. There is no such version. There is only a Planck law for net transfer, and that is the only quantity which can be measured. The misconception is widely spread and it my take some courage to free yourself from this spell. Have you tried, or is it enough for you that the misconception is common to turn it into a truth?

    SvaraRadera
  10. About the one-way, two-way issue.

    Can you be more explicit in what you really mean.

    How do you define heat transfer in this specific matter?

    How do you define heat?

    SvaraRadera
  11. You should read and ponder the book to find answers.

    SvaraRadera
  12. I have read some parts of that book now. And there are some serious issues, such that I will probably not spend any more time on it.

    First, you seem to want to model material oscillators, I don't really see the rational for that. Planck did it in his original approach but later changed it. There is a passage in the beginning of Bohm's Qantum Mechanics that discusses this issue.

    Later (p 63), you introduce some finite element scheme with some mesh size that you claim have physical correspondence. If I understand you right you argue that this is needed for coherent emission.

    That is just not true. The simplest counter example is ordinary hydrogen in dilute form ( Hydrogen spectral series ).

    Looks like ambitious work though. Is it only you who contributed or are there more persons behind this?

    SvaraRadera
  13. Claes Johnson17, januari 2013 04:05:

    "The misconception is widely spread and it my take some courage to free yourself from this spell"

    Why not assist us in freeing ourselves from this spell by providing us a little bit more detail? As already asked:

    Why do these radiometers on satellites measure much lower values of radiance at 667cm^-1 compared with 1000cm^-1 (from upward radiance)?

    When you take a surface radiometer and point it up at the sky in for example, the very dry cold Antarctic it measures much higher value of radiance at 667cm^-1 compared with 1000cm^-1.

    SvaraRadera
  14. The sensor which is sensitive to radiative contact with whatever is emitting/absorbing in a certain frequency band, takes on the temperature of the emitting/absorbing body in radiative equilibrium. Depending on the frequency this can be different looking down or up.

    SvaraRadera
  15. I asked:
    "Why do these radiometers on satellites measure much lower values of radiance at 667cm^-1 compared with 1000cm^-1 (from upward radiance)?

    When you take a surface radiometer and point it up at the sky in for example, the very dry cold Antarctic it measures much higher value of radiance at 667cm^-1 compared with 1000cm^-1.


    Claes said:

    " Depending on the frequency this can be different looking down or up."

    That's a description of what we see.

    Why specifically do we get these differences at the wavenumbers where CO2 is measured via spectroscopy to be a strong absorber?

    You've claimed it can't be CO2. So you must have a theory.

    Or perhaps you don't have a theory, perhaps you haven't thought this subject through.

    SvaraRadera
  16. Again: the instrument measures the temperature of an emitting/absorbing body within some frequency band, by radiative contact in equilibrium. Looking down it can thus record the temperature of CO2 at high altitude and a higher temp of water vapor at lower altitude. Looking up it can record high temp of CO2 at low altitude and low temp of outer space through the atmospheric window. The instrument can be made sensitive to a trace gas like CO2, but that does not say that the whole atmosphere radiates like CO2, only that the temp is the measured temp of CO2. if you understand that it is temperature which is measured and nor DLR or OLR, the mystery disappears together with GHE. Have you tried this line of thought?

    SvaraRadera
  17. Claes,

    You say the radiometer is measuring the temperature of CO2. Why is the CO2 colder than the water vapor when we look down from the satellite, but hotter than the water vapor when we look up from the surface?

    How is this possible?

    Of course in the crazy "last 100 years of physics" theory we can explain it very easily.

    Please help me understand how your theory explains this.

    SvaraRadera
  18. It is not strange. If you detector is sensitive to wave number 667 it may detect CO2 at high altitude looking down, thus detect CO2 at lower temp than water vapor, while looking up it may detect CO2 at low altitude, thus detect CO2 at higher temp than water vapor. What is your explanation? And what does the detector effectively detect? Radiance like DLR and OLR? Or do you agree that it is temperature?

    SvaraRadera
  19. Claes,

    Still trying to piece together your thesis.

    You commented (favorably) on the calculation by the illustrious Nahle of CO2's emissivity in the atmosphere. Under your new paradigm what is emissivity? [Under the "flawed 20th century physics world" it is the thermal emission of radiation/black body thermal emission of radiation].

    And do you have a formula for how to determine in advance what temperature (for a given wavenumber) the radiometer will "see"?

    SvaraRadera
  20. Since by definition absorptivity = emissivity, these terms are misleading by suggesting two-way heat transfer in and out, when there is only one-way heat transfer from warm to cold. Better is a neutral term like responsivity. A radiometer assumes the temperature of the radiating body within it's range of vision in space and frequency, from radiative equilibrium.

    SvaraRadera
  21. Are you trying to help me piece together your thesis?

    You favorably report on a calculation of emissivity as if it supports your thesis.

    When asked you say this term is misleading.

    So are you saying your article is misleading? You misled your readers?

    And please supply the formula as requested above.

    Saying "A radiometer assumes the temperature of the radiating body within it's range of vision in space and frequency, from radiative equilibrium." is not a formula.

    SvaraRadera
  22. Read my book on blackbody radiation and then return with questions.

    SvaraRadera
  23. Yes, radiative equilibrium is a formula:

    Temp of detector = Temp of source object.

    SvaraRadera