What explanation of the Greenhouse Effect do you use?

Discussion in 'Environment' started by IanC, May 19, 2019.

  1. IanC
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    IanC Gold Member

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    I looked for a reasonably scientific explanation of the GHE on Google and was very disappointed. You would think it would be everywhere but it isnt.

    I then specifically searched for the IPCC version. Imagine my surprise when 'denier' sites were the major places of discussion.

    How weak is their case if they are effectively hiding it? For the record, I believe in the GHE in principle as a very important part of atmospheric radiative physics. I don't see how the addition of more CO2 can cause huge changes though.

    What is your reference site for the GHE? Or do you just know it?

    I'll post up a few links later if no one cares to post theirs.
     
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  2. toobfreak
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    toobfreak Gold Member

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    The Greenhouse Effect, stated simply is any closed system where more infrared energy is trapped than released artificially raising the mean temperature above what it would be otherwise unless a thermal equilibrium is reached. What determines the equilibrium point or whether it becomes thermal runaway is the fact that as heat increases, so does the rate of radiative escape, hopefully to some point where the elevated rate of escape finally equals the incoming energy. It is at that point the system stops heating.
     
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  3. Likkmee
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    Likkmee Gold Member

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    The cow fart theory sounds good.
    Ever been to India ?
     
  4. Wuwei
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    Wuwei Gold Member

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    I found that a rich source of information on climate is given by the American Institute of Physics (AIP). It is more accessible and succinct than the IPCC. Here is one link titled Basic Radiation Calculations, but they show no mathematics.
    Basic Radiation Calculations

    The paragraph above the last says,

    Note: this Website does not cover developments from the 1980s forward in radiation models....
    Look at the top of the page to see a link to the Table of Contents to other pages.

    If you want more of the math for an idealized radiation aspect only, they refer to
    Idealized greenhouse model - Wikipedia

    However the model is a one layer atmosphere. They say,

    The simple one-level atmospheric model can be readily extended to a multiple-layer atmosphere. In this case the equations for the temperatures become a series of coupled equations.

    I have been working on the coupled equations and find that they are very easy to solve with simple assumptions for parameters, however it is a basis for making more complex computations. When I have time I will post what I got.

    .
     
  5. IanC
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    IanC Gold Member

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    Where is the link to your source? Or is that just your personal interpretation of what the GHE is?

    I'm not trying to harass you. I want to look at 'official' explanations.

    .
     
  6. IanC
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    IanC Gold Member

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    I too have a lot of faith in the radiative models to calculate energy transfer for a specific set of atmospheric constituents. I think the water feedback assumptions are wrong though.

    That said, I am looking for an explanation of the GHE that is suitable for laymen. And which hopefully doesn't include the phrase "97% of scientists agree".
     
    Last edited: May 19, 2019
  7. IanC
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    IanC Gold Member

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    An old IPCC explanation but the link is now broken-

    "
    From http://www.ipcc.ch/ipccreports/tar/wg1/518.htm

    Greenhouse effect
    Greenhouse gases effectively absorb infrared radiation, emitted by the Earth’s surface, by the atmosphere itself due to the same gases, and by clouds. Atmospheric radiation is emitted to all sides, including downward to the Earth’s surface. Thus greenhouse gases trap heat within the surface-troposphere system. This is called the natural greenhouse effect.
    Atmospheric radiation is strongly coupled to the temperature of the level at which it is emitted. In the troposphere the temperature generally decreases with height. Effectively, infrared radiation emitted to space originates from an altitude with a temperature of, on average, -19°C, in balance with the net incoming solar radiation, whereas the Earth’s surface is kept at a much higher temperature of, on average, +14°C.

    An increase in the concentration of greenhouse gases leads to an increased infrared opacity of the atmosphere, and therefore to an effective radiation into space from a higher altitude at a lower temperature. This causes a radiative forcing, an imbalance that can only be compensated for by an increase of the temperature of the surface-troposphere system. This is the enhanced greenhouse effect."

    Reasonably accurate? Maybe. Reasonably understandable? To me yes, but...

    GHGs that exist right now have a large effect. Predictions of the effect caused by an increase is much less straight forward.
     
  8. Wuwei
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    Wuwei Gold Member

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    The last two paragraphs bother me. I would like an estimate of the altitude where the output radiation is in balance with the input. The pressure is dropping exponentially with altitude so the number of GHGs molecules radiating drops exponentially. The temperature in Kevin is relatively constant compared to the exponential change in altitude. So I would think the first sentence of the second paragraph would be

    ....Atmospheric radiation is strongly coupled to the altitude of the level at which it is emitted.....

    The equipartition principle is always in effect so the radiation is proportional to the number of CO2 in excited states emitting their photons. That number follows the stronger density of CO2 function of altitude while temperature has a weaker linear function.

    .
     
  9. SSDD
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    SSDD Gold Member

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    The fact that you warmers have your own “versions” which are different from the mainstream version speaks volumes.
     
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  10. BlackFlag
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    BlackFlag BANNED

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    ^ thinks a magic man in the clouds will return and make it go away
     

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