The Energy Balance and the Greenhouse Effect: 3 of 3


This article wasn’t supposed to be so long, but it is important to understand the science behind the Greenhouse Effect (GHE).  My view is that net energy transfer to the atmosphere is the primary driver of the warmer atmosphere and the GHE.  While that isn’t currently the conventional approach, there is nothing that precludes it from being a better approach and there are some benefits.

The first benefit is that the ratio’s of convective and radiative heat transfer are more in line with each other.  In a typical situation with a 10-20 °C temperature difference between objects, the ratio of energy transfer between natural convection and radiative transfer should be of a comparable order of magnitude.  The net transfer shows a ratio of 0.74.  That the atmosphere doesn’t absorb all the energy skews the ratio a little.  The FT08 gives a ratio of 0.05.  This equation was modified for the horizontal surface for the Nusselt number from the basic derivation here.  This case is limited to small temperature gradients.

The Inconvenient Skeptic

Ratio of Convective to Radiative Heat Transfer: For hot bottom convecting upwards.

One benefit from my view is that it allows the different components of the overall GHE to be directly weighted and compared to each other.  If the assumption is made that half of the energy absorbed by the stratosphere (78 W/m2 total) and the other half by the troposphere, then the total energy radiated up by the troposphere is 159 W/m2.  If that energy is the primary cause of the GHE, then 159 W/m2 of energy is causing the 33 °C GHE.

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Fog surrounding the Space Shuttle.

Evaporation / Transpiration:

This is the largest source of energy transferred to the troposphere at 80 W/m2.  This accounts for 50.3% of the total.  If it is the same ratio of the GHE, then this accounts for 16.6 °C of the GHE.  When liquid water evaporates it takes energy away from the surface.  This causes a cooling effect at the surface.  When water vapor condenses in the atmosphere (to make clouds or fog depending on where it happens) the energy is then transferred to the atmosphere.  This is only part of why water is the most important part of the GHE.

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Direct absorption from the Sun

78 W/m2 of energy are directly absorbed by the atmosphere.  This is divided up into two parts.  The ozone layer strongly absorbs the different wavelengths of shortwave (SW) energy from the sun.  This is why the stratosphere is warm.  Almost none of the very high energy UV from the sun reaches the surface of the Earth.

The 2nd part is absorbed in the lower atmosphere by water vapor.  Since water vapor is very rare above the troposphere, the energy that can be absorbed by water vapor is absorbed in the troposphere.  The precise breakdown is difficult because clouds really alter this.  I will simply split the total in half.  It is probable that the stratosphere gets more than the troposphere.  The effect of that change would be to decrease the direct portion of the GHE.

If the troposphere does get 39 W/m2 then it is the 2nd most important part of the GHE at 24.5%.  CO2 does absorb a small portion of this amount, but at 1% it is not very significant and that absorption would take place much higher in the atmosphere as the CO2 concentration is mostly constant in the atmosphere.

The Inconvenient Skeptic

The portion of energy transferred to the Troposphere.

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Greenhouse Gas Absorption

At 23 W/m2 the absorption of longwave energy from the surface is 14.5% of the 33 °C total, or about 4.8 °C.  Of that water vapor is the most important.  It causes between 60-80% depending on cloud cover.  KT97 puts the clear sky at 60% and the cloud estimates put it around 80%.  Regions with high humidity also favor water vapor over CO2.

CO2 on average is 15-18% of the greenhouse gas absorption, or it is responsible for 0.72-0.86 °C of the total GHE.  If changing CO2 levels did increase this by a few percent, the contribution of CO2 would then be 0.74-0.88 °C.  This is a part of why I remain unconvinced that CO2 is capable of causing significant global warming.

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Dust Storm

Convection / Thermals

Last and actually least is direct convection of the air caused by the air collisions with the warm ground.  This warms the air which then circulates.  At 17 W/m2 it is the smallest contributor to the GHE at 10.7% of the total.  This means that convection by itself contributes 3.5 °C of the GHE.  Or about the same as water vapor by itself.

Here is a NASA picture that uses percentages of the total incoming solar energy to show the atmospheric energy balance.  You will see it is very similar to my own.

The Inconvenient Skeptic.

NASA illustration by Robert Simmon. The atmosphere radiates the equivalent of 59% of incoming sunlight back to space as thermal infrared energy, or heat. Where does the atmosphere get its energy? The atmosphere directly absorbs about 23% of incoming sunlight, and the remaining energy is transferred from the Earth’s surface by evaporation (25%), convection (5%), and thermal infrared radiation (a net of 5-6%). The remaining thermal infrared energy from the surface (12%) passes through the atmosphere and escapes to space. http://earthobservatory.nasa.gov/Features/EnergyBalance/images/atmosphere_energy_balance.jpg

Posted in Energy Balance and Radiative Heat Transfer by inconvenientskeptic on December 5th, 2010 at 5:15 am.

22 comments

This post has 22 comments

  1. Malaga View Dec 6th 2010

    Mmmmmmmm… so this is the average…. no heat arriving from the equator… no heat going to the poles…. no clouds… no weather… no seasons… no Northern Hemisphere…. no Southern Hemisphere… no tropics… no poles… no night… no daily variations… no maximum insolation… no minimum insolation… no oceans… no continents… no ice caps… no forests… no mountains… no below sea level… just average daylight everything… nothing really tangible… just a few percentages scattered around at random on a graphic.

    After a huge amount of foreplay everything seems to have gone very limp all of a sudden.

  2. inconvenientskeptic Dec 8th 2010

    Malaga,

    Sorry you are disappointed, but everything leads to more. This is a good approach to the issue and as always it will lead to more.

  3. Malaga View Dec 8th 2010

    Its getting late in the afternoon… there is hazy cloud… the sun is low in the sky… its the 8th of December… and at 16:00 CET the insolation at La Viñuela, Malaga measured 248 W/m²… and the temperature is a lovely 21.3ºC… so I will try to get this into perspective when I’m relaxing on the beach tomorrow :-)

  4. inconvenientskeptic Dec 8th 2010

    ROFL… I just finished up a 1149 mile drive through the snow and freezing temperatures…

  5. Glenn Tamblyn Dec 8th 2010

    John

    I am carrying this over from our previous discussion at http://theinconvenientskeptic.com/2010/11/the-earths-energy-balance-simple-overview/ to include what you have added here.

    You are trying to make 2 basic points here John, both of which are wrong. Firstly that the GH Effect is rather small and then the CO2 component of that is quite small. And then that the Convective & Radiative heat transfers ‘should’ for some reason be of a comparable magnitude.

    I will break my comments up into 3 sections

    1. That your figure of 23 W/M^2 for the GH Gas component is based on dodgy accounting practices and a bit of smoke & mirrors from your previous posts. And that your estimation of the CO2 component of this is wrong

    2. A more detailed description of the GH Effect and why CO2 is so significant.

    3. Why your idea that Convective & Radiative heat transfers ‘should’ be comparable is incorrect.

    Readers can focus on which section they find more interesting. Unfortunately, since I can’t post graphics, this needs to be a bit verbose. So bear with me…

    John. In your earlier posts on RHT you presented simple examples of radiative heat transfer between 2 objects – fire & hands, hands & ground. Simplistic descriptions, useful as far as they went but not a full description of the process – as I pointed out. You focused strongly on the importance of the NET energy transfer for temperature change. Then you introduced your term for ‘Forcing’, talking about a potential for heat transfer which was gobbledeegook. But it let you try to ‘claim’ the word ‘forcing’ as if you were using it in the same sense in which it is used in Climate Science – which it isn’t. Perhaps setting up a strawman but at the very least, using a very simplistic, illustrative description of Radiative Heat Transfer between 2 solid objects.

    Then you jump to KT and look at a more real world example. Energy transfer now between 4 components – the Sun, The Surface of the Earth, The Atmosphere & Deep Space. And at least one of those components CANNOT be treated like the surface of a solid object – Gas Radiation Transfer is totally different from radiation from a solid surface. And most engineering examples of Gas Radiation deal with situations where the gas is essentially at 1 temperature – a boiler or blast furnace for example.

    In the atmosphere we are dealing with a temperature range from +15C down to at least -60C. You don’t mention any of these complexities in your discussion. Thats fine in so far as you are engaging in a tutorial on the most basic aspect of RHT.

    Unfortunately you then extend the discussion way beyond this but continue with the simplistic analogies.

    A friend of mine is an amateur magician and I have looked at some of his stuff. One of the most basic concepts in magic is called Magic by Misdirection. If I can keep your attention focussed on what my right hand is doing, or the ‘big’ expression on my face, you wont notice what my left hand is doing.

    You are doing this – misdirection, although I will give you the benefit of the doubt and assume it is unintentional. After spending several posts fixating on RHT between 2 solid objects, you introduce Heat Transfer between 4 locations, one of which is a multi-temperature gas environment, and including heat transfers that are not just radiative but also convection and evapotranspiration. Then continue on as if the simplistic description from earlier is sufficient.

    At the very least an analysis of such a heat transfer system requires the use of a ‘network’ heat transfer analysis and goes way beyond the scope of your simple example.

    Then, having focussed your readers attention of the NET flows of RADIATIVE heat transfer between ONLY TWO OBJECTS, you slip in other energy sources and heat transfer processes and hope no one will notice. Gas Radiation, Convection, Evapotranspiration.

    So, you then compare BR with total SR absorbed by the atmosphere and come up with a figure of 23. You assume that the total SR absorbed by the atmosphere can be balanced against BR. Because in you illustrative, simplistic example you only considered RHT between 2 components.

    In this more real world example, energy flows INTO the atmosphere are 78+17+80+356 = 531. Flows OUT are 333 + 199 = 532.

    To then say that the 356 SR ONLY should be balanced against the 333 to get 23 is absurd & unphysical. All that energy flows into the atmosphere and swirls around. Then ANY part of that energy will ‘come out’ in proportion to what has flowed in.

    So that 333 Back radiation will be made up of the following flowing back down:
    223 Surface Radiation,
    49 Incoming Solar,
    11 Thermals ,
    50 Evapotranspiration.

    So you need to NET each of these flows. Not NET one flow against the BR and assume that the other flows play no part.
    This gives
    133 Surface Radiation absorbed by GH gases, 67.2%
    29 Incoming Solar, 14.6%
    6 Thermals , 3%
    30 Evapotranspiration. 15.2%

    In addition, as I explain in the second piece it is the radiation absorption properties that result in the BR and radiated to space not being 50/50 so the GH Gases are making an additional increase in the BR and hence the surface temperature

    Next you compare the percentage of CO2’s impact among the GH gases and rightly point out that water vapour contributes more. What you don’t mention is that an increase in the GH gases will produce a small temp change and this will in turn allow greater water vapour retention in the atmosphere and thus more GH Effect from the water. In addition, as temps rise the Thermal and ET flows will also increase as a consequence.

    If you where a company accountant John and the Auditors were called in to look at the books, they would ‘ping’ you for dodgy acounting. Your numbers seem contrived to present CO2 in the most irrelevent light.

  6. Glenn Tamblyn Dec 8th 2010

    Lets establish what the GH Effect is. It is actually made up of two separate components. And we are interested in its effects on surface temperatures since that is where we live

    First, ANY heat transfer process, not just radiation, that results in heat transfer from the Earth’s surface up into the atmosphere, RATHER than directly out to Space, WILL produce a GH Effect.

    So your comment John: ” My view is that net energy transfer to the atmosphere is the primary driver of the warmer atmosphere and the GHE” is essentially correct but I suspect you may not be seeing the real reason why it is.

    ANY absorption of heat by the atmosphere from the surface will cause a GH effect. This is because the surface can only radiate upwards, while the atmosphere can radiate in all directions, including down. So if some of the energy that is being lost by the surface is captured by the atmosphere (by whatever process) rather than getting out to space, part of that will be re-radiated BACK down to the surface – GH Effect

    Lets start with an Earth with no atmosphere at all. So no reflection off the atmosphere, no reflection off clouds, no absorption by the atmosphere, no thermals, no evapotranspiration, or Back Radiation. So incoming solar is 341. Assuming that the same percentage is reflected from the surface, absorbed by the surface is 341 x (161/184) = 298. Therefore SR = 298. Everything else is zero

    Now consider a hypothetical version of the KT diagram from the earlier post but with an atmosphere that doesn’t absorb any radiation at all. But reflection due to the atmosphere & clouds still occurs.

    – Absorbed by Atmosphere from Solar (ABAS) is now 0 not 78
    – Absorbed by Surface (ABS) is now 229 (Allowing for the previous ABAS of 78 reaching the surface but being partly reflected from the surface)
    – Thermals (TH) is still 17
    – EvapoTranspiration (ET) is still 80
    – Absorbed by Atmosphere from Earth (ABAE) is 0
    So Total Absorbed by the Atmosphere (TABA) is 97

    Assume 1/2 of this is then radiated by the atmosphere to space and 1/2 back to the Earth,
    – So Back Radiation (BR) is 48.5
    – Balancing the flows, Surface Radiation (SR) is then 229 + 48.5 = 277.5
    which all goes out through the atmospheric window as SR
    – Emitted by Atmosphere (EBA) is also 48.5

    277.5 is lower than the no atmosphere case because of the reflection of incoming solar from clouds. Obviously, with only 277.5 radiating from the surface rather than 396, the surface temperature is VERY much colder. In reality the TH and ET flows would be much lower than these figures, since in a colder world they would not be nearly as great, so the SR value would be EVEN SMALLER STILL. But this is a world that still has SOME GH Effect. And after allowing for the reflection from clouds, it isn’t much different from a world with no atmosphere.

    Next we add back the amount absorbed from Incoming solar – 78. But still leave the atmosphere transparent to Outgoing radiation. The new balance is now
    ABAS = 78, ABS = 161, TABA = 175(17+80+78), BR = 87.5 (175/2), SR = 161+87.5 = 248.5

    THIS IS LESS THAN THE PREVIOUS CASE!!!

    Absorption of ABAS by the atmosphere has a COOLING EFFECT on the surface
    because some of the energy in ABAS is reradiated back to space and never reaches the Earth.

    So your inclusion of this in your pie chart as part of the GH Effect is incorrect. If anything you should include this as a NEGATIVE TERM.

    Now lets look at the second part of the GH Effect – the radiation absorption properties of the so called GH Gases – Water, CO2, Nitrous Oxide, Methane, Ozone, CFC’s etc.

    This brings us back to the KT diagram. What do we see that is different from my previous example?
    – 90% of the SR is now absorbed by the atmosphere with only 10% making it out through the atmospheric window.
    – BR is much larger
    – The ratio between BR and EBA, the two parts of the atmosphere’s radiation, is no longer 50/50.

    What is this saying? Most of the energy radiated from the surface, 90%, is absorbed by the atmosphere. So this has added a major additional atmosphere absorption mechanism, over and above absorption through TH & ET, greatly increasing the GH Effect.

    And secondly, a smaller percentage of the energy absorbed and then re-radiated by the atmosphere is making it out to space.

    This is because of the characteristics of the GH Gases. They absorb a lot of the energy coming up from the Earth – 90%. In fact they absorb most of it in the lower atmosphere. Once it is absorbed by the atmosphere, this energy bounces around, up, down, left, right, mixing with all the other energy sources.

    Since most of the lower atmosphere
    has enough GH gases in it to be ‘optically thick’, most radiation can only escape from the atmosphere, rather than being RE-ABSORBED within the atmosphere, when its path isn’t blocked by GH Gases. This happens relatively close to the surface. Or high in the atmosphere where the reduction in atmospheric density reduces the ‘blockage’. So radiation
    can ‘get out’ of the atmosphere and go somewhere else when it is close to the surface or high up. Otherwise it just cycles around and around.

    Because the upper atmosphere is much colder than the surface, the Stefan-Boltzmann Equation dictates that it cannot radiate as much energy as the lower atmosphere which is warmer.

    So we have a basic situation where energy is bouncing around inside the atmosphere. Its movement back to the surface is based on a relatively warm temperature when the ‘path length’ is short. In the upper atmosphere, when lower density makes the atmosphere not optically thick, the much colder temperature limits how much radiation can get out to space.

    It is this interaction between temperature variation with altitude, and optical thickness due to GH gas concentrations that produces the asymetry between BR & EBA.

    So Summarising this
    No Atmosphere SR = 298 Temp = -5
    Atmosphere but no absorption SR = 277.5 Temp = -10
    Atmosphere and absorption of incoming only SR = 248.5 Temp = -17
    Full current situation SR = 396 Temp = +15

    In reality, changes in TH & ET in a colder world would magnify these differences. And this assumes that surface albedo is unchanged which is unreasonable.

    So the existance of the GH Gases changes the balance hugely.

    Now what happens if we add more GH Gases. Add CO2, Methane, Nitrous Oxide etc. The atmospheric window from the surface is currently 40. Thats around 10% of the flow. What if additional GH gases narrow that to 9% for example?

    An additional 4 doesn’t get out to space and is absorbed by the atmosphere. It can’t be reradiated out to space since this is limited by the temperature of the upper atmosphere. So the lower atmosphere heats a little until the BR is now 337 and the atmosphere comes back into thermal balance.

    But now the surface isn’t in balance. It is gaining 4. So the surface starts to heat and SR rises. Most of this increase is absorbed by the atmosphere but some gets out through the atmospheric window. And the rest comes back down as increased BR. So we have a cycle of atmospheric and surface heating until a new balance point is reached. What is that point? It occurs when SR has grown to the point that 40 W/M^2 can again get out through an atmospheric window that is now only 9% rather than 10%.

    When SR has risen to 40/0.09 = 444, Temp = +23

    Is there anything else that could have an impact on this? Well, if the lower atmosphere is heating, some of that might cause some heating in the upper atmosphere. So at the altitude at which the air is no longer ‘optically thick’, if it is warmer then additional heat could get out to space that way, resulting in the new thermal balance at the surface being lower, but still warmer than the current situation.

    Balanced against this is the fact that with more GH gases the altitude at which the air stops being ‘optically thick’ increases, lowering the radiation temperature.

    I can’t tell you what the balance is between these two effects, they may diminish the surface warming or they may enhance it – dunno.

    So John. Your Pie Chart is quite wrong. GH Gases are major drivers of the GH Effect, Incoming Solar absorbed by the atmosphere is a net cooling and shouldn’t be included, and human released GH Gases, particularly CO2 are very important since changes in their levels initiate temperature changes and then changes in Water Vapour, Thermals & ET magnify that effect.

    Like the first few boulders that start an avalanche, those first few rocks may not be the bulk of the slide, but they are the important part because they trigger it.

  7. Glenn Tamblyn Dec 8th 2010

    Finally John, this idea that the convective & radiative flows ‘should’ be similar. I have never heard that contention put forward before. Then you put up an equation for which you give very little explanation. The site you link to – DrPhysics – does contain something similar but that is in the context of heat transfer from the human body – hardly a comparable situation to heat transfer for an entire planet.

    Lets look at some of the components of the equation.
    To is ambient temperature. What value is applicable here? +15, -60? Since this value is cubed, these differences are hugely important
    e Emmissivity. That is valid for a surface but is a meaningless concept for a gas.
    L the Characteristic Length. In the example at DrPhysics this is 2 metres since they are talking about the human body. What is yours? A metre, The circumference of the Earth, the height of the Atmosphere?
    Nu Nusselts Number. What value does this have since it is based on the ratio of conductive to convective heat transfer within the thermal boundary layer. How tall is the boundary layer? The very thin boundary layer around normal objects that are common in engineering problems? Or the 1 kilometer thick boundary layer of the earths atmosphere as it applies in meteorology. Are ou suggesting that conduction is meaningful over a height of a kilometer???

    So the equation you have added is utterly meaningless in this context without a lot more detail and some very more precise quantification of the terms within it.

    As to your general contention that the flows should be comparable in size, a comment you have made previously – why should they? You have commented that engineers who deal in heat transfer have this expectation. Quite possibly, but how does that transfer to the context of the heat balance of a planetary atmosphere?

    Engineering operates with a lot of ‘rules-of-thumb’ that are useful tools and short cuts in the day to day practice of engineering. So an observation such as this may be valid in their working context, dealing with boilers, furnaces, calculating the cooling load for a building etc. Small scale structures and phenomena. The fallacy is that these rules of thumb can then be extrapolated to very different contexts and particularly scales such as a complete planetary atmosphere.

    Take an analogy. An engineer who spends their working life designing factory machines. They deal in Newtonian Mechanics and standard Electronics. They will have a range of rules of thumb that they use in their working life. Then ask that engineer to design something like the GRACE orbital gravity sensor satellites. 2 satellites flying in formation, that use very precise measurement of the changes in the distance between them to measure the local gravity below. Will their rules of thumb from their past experience be any use to them here? Now the mechanics are non-Newtonian, Electronics needs to allow for strange behaviour due to cosmic ray bombardment, orbital trajectories are influenced by atmospheric drag, they need to understand the quantum mechanical impact of temperature changes on the lasers measuring the distance between the satellites.

    Will this engineers working experience provide them with the ‘tools’ they need to do the job. Or will they get it wrong because they don’t recognise that their ‘tools’ aren’t relevent and that they need to go right back to basics

    I have seen this before online John. Engineers, Geologists, Chemists, Economists trying to use the tools of their trade to critique (and usually reject) the findings of Climate Science. They fail because they are trying to apply their ‘domain’ knowledge outside their domain. So a geologist I had a conversation with tried to tell me that CO2 absorption by the ocean couldn’t lead to problems with carbonate saturation levels because the size of the ocean is so great that carbonate levels can’t vary that much. But he did’t understand the nature of circulation in the ocean; that the absorbed CO2 isn’t distributed evenly through the ocean but rather is concentrated in the top 100 metres or so and carbonate levels therefore can change markedly. He failed because he didn’t take into account Oceanography.

    I suspect you are falling into the same trap here John, applying Domain knowledge about convection and radiation in small-world scale phenomena and then presuming that this understanding applies on a far more macroscopic scale. Yes engineers who deal with heat transfer may have this rule of thumb. But it isn’t applicable in this vastly different situation.

    So rather than diagrams such as KT being wrong because they don’t match the understanding of heat transfer held by engineers, it is the engineers who are wrong in thinking that their understanding is applicable in this different context without going back to basics.

    And an idea such as this that the heat transfers ‘should’ be of comparable magnitude is certainly not transferable to an entire planetary atmosphere.

  8. inconvenientskeptic Dec 8th 2010

    I am glad Glenn recognize’s the significance of this which is why he disagrees with it. I have been in transit, but will get a reply to this soon. I might have to article it a little bit to break it down.

    :-)

  9. Malaga View Dec 9th 2010

    First, ANY heat transfer process, not just radiation, that results in heat transfer from the Earth’s surface up into the atmosphere, RATHER than directly out to Space, WILL produce a GH Effect.

    That statement I agree with… but the important point to me is that by definition this means ALL the components of the atmosphere are Green House Gases. Therefore, the whole concept of Green House Gases is really a misdirection… and the emphasis placed upon the 0.039% of the atmosphere that is CO2 is really a misdirection… this seems like an extreme example of the tail wagging the dog.

    This is supported by a few observations:

    THERMOS flasks do not use CO2 to reduce heat loss.

    The geological history of the earth indicates that the earth has not overheated when CO2 was many times greater than current levels.

    The earth is predominately covered in water and any additional heating of the earth will very quickly be offset by increased levels of evaporation.

    Overall, the geological record seems to indicate that the atmosphere works as a temperature regulator especially with regard to maximum temperatures. This seems to support the view that H2O is the major volatile element in the climate system. It is the only part of the atmosphere that changes state, it is the only part of the atmosphere that cycles through gas, liquid and solid states… and it is this state cycling that both absorbs and releases heat. Additionally, the amount of H2O in the atmosphere is also variable… there is more H2O in the air when it warm… and less H2O when it is cold. I would also note that H2O (in the form of seas, oceans and lakes) is a huge heat sink which helps moderate rapid changes.

    In conclusion… my view of the atmosphere, climate and weather is that it is a huge charged system that contains latent heat. The movement and state cycling of H2O (in the oceans and the atmosphere) drives the weather system…and the longer term dynamics of the water cycle drives climate… the variable amounts of H2O in the atmosphere are a response to the overall heat pumped into this charged system from the sun… and the cycling of H2O through its gas, liquid and solid states that limits the maximum temperature of the atmosphere.

    My main point is that you are addressing this whole topic in the wrong way. The earth is not a black body system surrounded by dry air. The climate of the earth is a charged system regulated by H2O which continually responds to changes of insolation.

  10. inconvenientskeptic Dec 9th 2010

    Malaga,
    I would say thing differently, but I don’t disagree with you. Water is the key to everything. What I am doing is building things one step at a time. Sometimes the steps are awkward because explaining things is easier from one place from another. One of the biggest problems with most people understanding the issues is that there are so many aspects that are not properly explained. I am trying to provide a foundation that people can use to understand other things.

  11. inconvenientskeptic Dec 9th 2010

    Glenn,

    You are mis-stating information. In KT97 they state that the net Longwave flux is 66 W/m2. This does not involve any of the items that you have pulled in. KT97 even uses the simple energy balance SW – LW – LH – SH = 0 to determine the sensible (convection) in the 97 paper. Nowhere does that paper imply or state that the atmosphere absorbs 133 W/m2.

    In engineering the most common practice is to determine the simplest, most effective comparison. While the mechanics of transfer from a solid to a gas are different, a comparable average can be used. Some transfer takes place near the surface where there is a small temperature gradient, hence very little net heat transfer, very humid places are the best example. Other transfer takes place at higher altitudes with a much greater temperature difference, arid or polar regions would behave in this manner. Much like KT use a column average to represent the entire Earth, it is perfectly acceptable to use a altitude average. By definition such an average exists. So not using it is foolish. The studies themselves show that the average radiative downward flux is 333 W/m2 (KT08). That gives a net energy leaving the surface as 63 W/m2. There is nothing inaccurate or misleading in that. KT08 themselves state the net LW is 63 W/m2. Read the paper.

    As for you complaints about comparing convective and radiative transfer. You did not pay attention. They use an upright cylinder example to compare low temperature difference to compare to the human body. I did a similar analysis using a horizontal surface to determine the ratio. Unless you are saying that the atmosphere above the surface isn’t transferring heat with the surface, the ratio is valid.

    NASA’s Earth Observatory agrees that the amount of energy absorbed by the atmosphere from convection and absorbed by greenhouse gases is comparable at 5-6% of the incoming solar total. That is from the NASA website. Again, I did not make any of this up.

    Your accusations of being mis-leading are unsupported. That the measured radiative flux matches Stefan-Boltzmann both upwards and downwards. That indicates that the laws of radiative heat transfer are in effect. Therefore the net energy transfer is from the surface to the atmosphere as the surface is the temperature boundary for the lower atmosphere. The net energy flows upwards from higher temperature to lower temperature as the laws of thermodynamics dictate. Once the top of the troposphere is reached, most energy escapes to space from the troposphere. Some small amount continues to be absorbed in certain wavelengths, primarily ozone and CO2.

    You are the only engineer I have spoken to that does not agree with the science as stated. Even the ones that think CO2 is significantly influencing climate agree that what I have presented is accurate. The real mis-direction is the insertion of radiative flux for energy transfer. I did not perform that little piece of magic.

  12. inconvenientskeptic Dec 9th 2010
  13. Glenn Tamblyn Dec 12th 2010

    Malaga

    “but the important point to me is that by definition this means ALL the components of the atmosphere are Green House Gases. Therefore, the whole concept of Green House Gases is really a misdirection… and the emphasis placed upon the 0.039% of the atmosphere that is CO2 is really a misdirection… this seems like an extreme example of the tail wagging the dog”

    That is not the poiunt I was making. The GH Effect is too components, 1 is the general fact that ANYTHING that transfers heat into the atmosphere will produce some degree of GH Effect simply due to the GENERAL radiation EMISION properties of ALL substances and the geometry of that radiation from the atmosphere.

    The term Greenhouse Gases as it is commonly used refers to the specific radiation ABSORPTION properties of the GH gases. As such they contribute STRONGLY to radiation absorption by the atmosphere and then to the more general GH Effect. So comparing CO2’s percentage in tha atmosphere is irrelevent. What matters is CO2’s percentage contribution to the general ABSORPTION of radiation that then feeds into the GH Effect.

    Consider an analogy. When you make a cup of instant coffee, you take a small spoon of coffee crystals and add a cup of boiling water. How can the coffee crystals make any difference to the cup of coffee when it is mainly water? Because the coffee adds to the taste. The water has no taste so dousn’t contribute to the taste.

  14. Malaga View Dec 12th 2010

    Just read a wonderful posting by Willis Eschenbach over at WUWT that describes climate as a heat engine… it is music to my ears… http://wattsupwiththat.com/2010/12/11/which-way-to-the-feedback/

    His Circulation in a Solar Driven Heat Engine diagram is a huge step in the right direction… it includes horizontal flows… like heat from the equator.

  15. Glenn Tamblyn Dec 12th 2010

    John

    You are missing the point. I am not disputing the fluxes – KT08, KT97 or Nasa. All of them are comparable exercises in accounting, tracking where energy comes and goes.

    However, you are then bringing in an extra dimension, trying to argue that underlying physical process such as the absorptive aspects of the GH Effect can be evaluated against the net value of some flows.

    You are trying to draw conclusion from the size of the flows, rather than simply observing what they are, which is all that your sources are doing.

    How can you argue that GH gases are a small component when the LARGEST SNGLE FLUX INTO the atmosphere – 356 – occurs BECAUSE the GH gases absorb nearly 90% of the radiation from the surface.

    Are you saying that of the 356 into the atmosphere, 333 of that flows back to the surface!

    But of the Thermal, ET and Absorbed Solar fluxes into the atmosphere, EVERT LAST WATT OF THEM ONLY FLOWS TO SPACE! NONE of it flows back down!!??!!

    Can you put forward the most vaguely comprehensible mechanism by which the Atmosphere ‘knows’ – ‘Gee, that watt is from surface radiation, send it down. That watt is from Thermals, send it up’

    Are you suggesting that the atmosphere is intelligent at the photon by photon level?

    Think like an engineeer John. Don’t just talk about data. Describe the mechanism. Because otherwise, how do you know that you are drawing faulty conclusion through not considering the mechanism.

    To argue that the LW fluxes up and down can be balanced out as a NET flux for MORE than accounting purposes, to actually EVALUATE A PHYSICAL MECHANISM BASED ON THIS NET FLOW DOESN’T MAKE SENSE!! THE EVALUATION OF THE PHYSICAL PROCESSES NEEDS TO BE DONE ON A FLOW BY FLOW BASIS, NOT ON THE NET OF SEVERAL FLOWS.

    Decide John. Are you just engaging in an accounting exercise. Or if you wish to draw conclusions, start discussing underlying mechanisms or otherwise you are just engaging in a bit of Sophistry.

  16. Malaga View Dec 12th 2010

    Consider an analogy. When you make a cup of instant coffee, you take a small spoon of coffee crystals and add a cup of boiling water. How can the coffee crystals make any difference to the cup of coffee when it is mainly water? Because the coffee adds to the taste. The water has no taste so dousn’t contribute to the taste.

    Mmmmm… the coffee crystals make no noticable difference to the temperature of the water… it is still hot… which is how I like my coffee… so we are looking good so far.

    Now lets try it the other way round…. pour cold water into the cup… then heat up your coffee crystals… and I mean really heat them up… then add them to your cup of cold water… and what do you have… cold water with some burnt coffee crystals floating about… thats not the way I like my coffee… roll eyes.

  17. Malaga View Dec 12th 2010

    Are you just engaging in an accounting exercise.

    Getting the number pinned down seems like a good place to start… accounting for and balancing the flows would be an added bonus.

    Starting with conclusions, statements, sophistry and antagonism is not a fruitful approach in my experience.

  18. inconvenientskeptic Dec 12th 2010

    Glenn,

    Consider what you are saying. Your statement and claim is that the atmosphere provides more energy for warming than the sun. Consider a model where the atmosphere provided TWICE the energy to the surface than the sun.

    The atmosphere provides and insulative effect. It does not warm the surface any more than insulation in a house warms the house. It reduces the rate of heat loss so the house is not at thermal equilibrium with the outside.

    The atmosphere is exactly like the insulation in a house. It does not warm the house, but it INSULATES the house. Look at the temperature profile of the troposphere… It is exactly like the temperature profile of the insulation for a house to a cold exterior.

    Seriously… Radiative heat transfer in the atmosphere is not some magical warming device. You are way off base on this.

    If you know of an insulation that causes warming inside the house then patent it and get rich. Otherwise you are mocking the laws of thermodynamics.

  19. Richard Sharpe Dec 13th 2010

    Hmmm, if there is energy entering the atmosphere and energy leaving the atmosphere (or some layer thereof) the temperature must be a function of the net energy in the atmosphere …

    Is this wrong?

    It’s all about the energy, isn’t it?

  20. inconvenientskeptic Dec 13th 2010

    An object can only change temperature if it gains or loses energy.

    You are correct. It is all about the energy.

  21. Glenn Tamblyn Dec 21st 2010

    John

    This seems to be a splitting of semantic hairs about the meaning of the word ‘warms’. I have a house with a log fire but no insulation and when it is zero outside the inside temp is 10 DegC. Then I add some insulation and now the same log fire is able to keep the temperature at a more comfortable 20 DegC. Has the insulation ‘warmed’ the house? Yes, in the sense that the house is warmer because of the presence of the insulation.

    What matters is the mechanism by which the insulation works, not simply its end result.

    Mineral Wool and other bulk type insulations in a house work by interposing a layer of material between the walls that makes the wall less thermally conductive, restricts convective flow within the wall cavity and makes the wall cavity opaque so that radiative transfer across the cavity is very restricted. All of these make the wall harder for heat to travel through.

    In contrast reflective foil insulation in a wall works by actually reflecting much of the heat radiated across the cavity back to the other side. Instead of blocking heat flow in one direction, it causes an additional heat flow in the reverse direction. So the NET flow is lowered by creating a reverse flow.

    This is the same situation with how the GH Effect works. It is like having reflective foil in the sky.

    As to this comment “Your statement and claim is that the atmosphere provides more energy for warming than the sun. Consider a model where the atmosphere provided TWICE the energy to the surface than the sun” OK

    Lets do this with an analogy. We have a tall water tank. A pipe at the top provides a constant flow into the tank(The Sun). At the bottom an outlet pipe lets the water drain away(Radiation to Space). What is the level in the tank(Total Heat Content of the system)?

    This depends on the size of the outlet. The water level will rise until the water pressure at the bottom of the tank(Temperature) is high enough to cause the flow in the outlet pipe to match the inlet. So when the tank is empty, outflow is smaller than inflow but steadily increases as the level in the tank rises. Eventually the level stabilises when the two flow rates match.

    Then we add a pump fitted to the outlet pipe. This recirculates some of the water in the outlet pipe BACK into the tank. Now the effective flow rate out of the tank has been reduced due to the recirculation. The flow rate of water actually making it all the way OUT of the outlet pipe is the initial flow rate INTO the outlet LESS the recirculation flow rate BACK to the tank.

    What will the new level of the tank be?

    Higher. It will rise until the pressure at the bottom of the tank is high enough to generate a flow INTO the outlet pipe such that the flow remaining AFTER the recirculation pump has drawn some away matches the inlet flow into the top of the tank.

    So if the inlet is 10 litres a second and the pump recirculates 2/3 of the flow in the outlet pipe, then the flow INTO the outlet pipe needs to be 30 litres a second so that the flow OUT of the outlet pipe will 10 litres per second, with 20 litres per second being recirculated.

    If the pump can then recirculate 9/10 of the outlet flow then the level will rise until the flow INTO the outlet pipe reaches 100 litres a second so that the flow OUT of the outlet pipe will be 10 litres per second with 90 litres per second being recirculated.

    What is there about the size of the inlet flow at the top of the tank that requires that the flow through the pump needs to be ‘correlated’ with it in some way? There is no reason why the pump couldn’t recirculate a 100 times the inlet flow, so long as a small part of the outlet isn’t captured by the pump.

    That reflective foil in the sky just needs to be more reflective, as long as it isn’t 100%!

    The fallacy in what you are saying seems to be that you are expecting that energy that flows THROUGH a system needs to be correlated with internal energy that recirculates WITHIN a system. The two flows do not have any correlation at all so long as the underlying physical process exists to enable each separate flow, and that the system has an internal mechanism for accumulating energy.

    This is a classic example of not getting your system boundaries right.

  22. Jacob Mack Jan 31st 2011

    I am a new reader of your blog John. I read many entries and comments prior to posting my own comment. You are very much correct on every major point. Keep up the goodf work!

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