Guest post by Ira Glickstein
Albert Einstein was a great theoretical physicist, with all the requisite mathematical tools. However, he rejected purely mathematical abstraction and resorted to physical analogy for his most basic insights. For example, he imagined a man in a closed elevator being transported to space far from any external mass and then subjected to accelerating speeds. That man could not tell the difference between gravity on Earth and acceleration in space, thus, concluded Einstein, gravity and acceleration are equivalent, which is the cornerstone of his theory of relativity. Einstein never fully bought into the mainstream interpretation of quantum mechanics that he and others have called quantum weirdness and spooky action at a distance.
So, if some Watts Up With That? readers have trouble accepting the atmospheric “greenhouse” effect because of the lack of a good physical analogy, you are in fine company.
For example, in the discussion following Willis Eschenbach’s excellent People Living in Glass Planets, a commenter “PJP”, challenged the atmospheric “greenhouse” effect:
“The incoming energy (from the sun) you express in w/m^2, lets simplify it even more and say that energy is delivered in truckloads. Lets say we get 2 truckloads per hour. … when we come to your semi-transparent shell [representing greenhouse gases (GHG) in the atmosphere], you are still getting two truckloads per hour, but you say that these two truckloads are delivered to both the earth and to the shell — that makes 4 truckloads/hr. Where did the extra two truckloads come from?”
In that thread, I posted a comment with an analogy of truckloads of orange juice, representing short-wave radiation from Sun to Earth, and truckloads of blueberry juice, representing longwave radiation between Earth and the Atmosphere and back out to Space. A later commenter, “davidmhoffer” said “Ira, That was a brilliant explanation. …”
This Post is a further elaboration of my physical analogy, using a pitching machine and yellow and purple balls in place of the truckfulls of juice.
Graphic 1 shows the initial conditions. The Sun is a ball pitching machine that, when we turn it on, will throw a steady stream of yellow balls towards the tray of a weight scale, which represents the Earth. The reading on the scale is analogized to “temperature” and, with the Sun turned off, reads “0” arbitrary units.
TURN ON THE “SUN”
Graphic 2 shows what happens when the Sun is turned on and there are no GHG in the Atmosphere. The stream of yellow balls impact the tray atop the weight scale and compress the springs within the well-damped scale until equilibrium is reached. The scale reads “1”. This is analogous to the temperature the Earth would reach in the absence of GHG.
The balls bounce off the tray and, for illustrative purposes, turn purple in color. This is my way of showing that Sun radiative energy is mostly in the “shortwave” visible and near-visible region (about 0.3μ to 1μ) and that radiative energy from the warmed Earth is mostly in the “longwave” infrared region (about 6μ to 20μ). The Greek letter “μ” (mu) stands for a unit of length called the “micron” which is a millionth of a meter.
Since, at this stage of my physical analogy, there are no GHG in the Atmosphere, the purple balls go off into Space where they are not heard from again. You can assume the balls simply “bounce” off like reflected light in a mirror, but, in the actual case, the energy in the visible and near-visible light from the Sun is absorbed and warms the Earth and then the Earth emits infrared radiation out towards Space. Although “bounce” is different from “absorb and re-emit” the net effect is the same in terms of energy transfer.
If we assume the balls and traytop are perfectly elastic, and if the well-damped scale does not move once the springs are compressed and equilibrium is reached, there is no work done to the weight scale. Therefore, Energy IN = Energy OUT. The purple balls going out to Space have the same amount of energy as the yellow balls that impacted the Earth.
ADD GHG TO THE “ATMOSPHERE”
Graphic 3 shows what happens when we introduce GHG into the Atmosphere. The yellow balls, representing shortwave radiation from the Sun to which GHG are transparent, whiz right through and impact the weight scale and push it down as before.
However, the purple balls, representing longwave radiation from the Earth, are intercepted by the Atmosphere. In my simplified physical analogy, the Atmosphere splits each purple ball in two, re-emiting one half-ball back towards the Earth and the other half-ball out to Space. Again, you can assume that half of the balls “bounce” off the Atmosphere back to Earth like reflected light from a half-silvered mirror and the other half pass through out towards Space. In the actual case, it is “absorb and re-emit half in each direction” but the net effect is the same in terms of energy transfer.
OK, here is the part where you should pay close attention. The purple half-balls that are re-emitted by the Atmosphere towards Earth impact the tray of the weight scale and press against the springs with about half the force of the original yellow balls. So, at this stage, when equilibrium is reached, the well-damped scale reads “1.5” arbitrary units.
But, we are not done yet. The purple half-balls are absorbed by the Earth, and re-emitted towards Space. Then they are re-absorbed by the Atmosphere and once again split into quarter-balls, half of which head back down to Earth and re-impact the weight scale. Now it reads “1.75”. As you can see, the purple balls continue to get split into ever smaller balls as they bounce back and forth and half head out to Space. The net effect on the weight scale is the sum of 1 (from the yellow balls) + 1/2 + 1/4 + 1/8 + 1/16 and so on (from the purple balls). That expression has a limit of “2”, which is approximately what the scale will read when equilibrium is reached.
Again, the well-damped scale does not move once the springs are compressed and equilibrium is reached, so there is no work done to the weight scale. Therefore, Energy IN = Energy OUT. The purple balls going out to Space have the same amount of energy as the yellow balls that impacted the Earth. But the “temperature” of the Earth, as analogized by the reading on the weight scale, has increased.
DOUBLE THE GHG IN THE “ATMOSPHERE”
Graphic 4 is the final step in my physical analogy. Let us double the GHG in the Atmosphere. (NOTE: I am assuming that the doubling includes ALL the GHG, most especially water vapor, and not simply CO2!) This is represented by putting a second layer of Atmosphere into the physical analogy.
The purple balls emitted towards Space by the first layer of the Atmosphere are intercepted by the second layer, where they are absorbed, and smaller balls are re-emited in each direction. The downward heading balls from the upper atmosphere are intercepted by the lower Atmosphere and half is re-emitted down towards the weight scale that represents Earth. Once again, they compress the springs in the weight scale increasing the reading a bit, and are re-emitted back up. The purple balls get halved and bounce around up and down between Earth and the two layers of the Atmosphere, further increasing the reading on the scale once equilibrium is reached.
Again, the well-damped scale does not move once the springs are compressed and equilibrium is reached, so there is no work done to the weight scale. Therefore, Energy IN = Energy OUT. The purple balls going out to Space have the same amount of energy as the yellow balls that impacted the Earth. But the “temperature” of the Earth, as analogized by the reading on the weight scale, has increased due to the doubling of GHG in the Atmosphere.
WHAT I LEFT OUT OF THE PHYSICAL ANALOGY
Any simplified analogy is, by its very nature, much less than the very complex situation it is meant to analogize. Here is some of what is left out:
- My purple balls are re-emitted in only two directions, either up or down. In the real world, longwave radiation is emitted in all directions, including sideways.
- My purple balls are all totally absorbed by the Atmosphere and re-emitted. In the real-world, a substantial amount of longwave radiation is re-emitted from the Earth and the Atmosphere in the 9μ to 12μ band where the Atmosphere is nearly-transparent. A substantial portion of the radiation from Earth and the Atmosphere thus passes through the Atmosphere to Space without interception.
- My physical analogy addresses only radiative energy transfer. In the real-world, energy transfer from the Sun to Earth and Earth to Space is purely radiative. However, the Earth transfers a considerable amount of energy to the Atmosphere via convection and conduction, in the form of winds, precipitation, thunderstorms, etc. These effects are absent from my analogy.
- I represent the Atmosphere as a single shell, when, in fact, it has many layers with lots of interaction between layers.
- I represent doubling of GHG as adding another shell, when, in fact, doubling of GHG, if it occured (and if it included not just CO2 but also a doubling of water vapor and other GHG) would increase the density of those gases in the Atmosphere and not necessarily increase its height significantly.
- In my analogy, all the energy from the Sun strikes and is absorbed by the Earth. In the real-world, up to a third of it is reflected back to Space from light-colored surfaces (albedo) such as snow, ice, clouds, and the white roof of Energy Secretary Chu’s home :^). If a moderately warmer Earth, due to increased GHG, evaporates more water vapor into the atmosphere, and if that causes more clouds to form, that could increase the Earth’s albedo to counteract a substantial portion of the additional warming.
I am sure WUWT readers will find other issues with my physical analogy. However, the point of this posting is to convince those WUWT readers, who, like Einstein, need a physical analogy before they will accept any mathematical abstraction, that the atmospheric “greenhouse” effect is indeed real, even though estimates of climate sensitivity to doubling of CO2 are most likely way over-estimated by the official climate Team. When I was an Electrical Engineering undergrad, I earned a well-deserved “D” in Fields and Waves because I could not create a physical analogy in my overly-anal mind of Maxwell’s equations or picture the “curl” or any of the other esoteric stuff in that course. Therefore, those WUWT readers who need a physical analogy are in great company – Einstein and Glickstein :^).
I plan to make additional postings in this series, addressing some implications of the 9μ to 12μ portion of the longwave radiation band where the Atmosphere is nearly-transparent, as well as other atmospheric “greenhouse” issues. I look forward to your comments!
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Dr. G.
With respect, as they say when they’re about to get stuck right in.
With respect, I cannot fault your simple analogy, with the exception of a couple of small quibbles:
(1) I presume in later episodes you will explain how clouds and water vapour and such like complicate your very clear exposition.
(2) How does you model explain the paleontological evidence that in times long gone, somtimes there was much more CO2 than a mere doubling would entail, yet temperature remained quite cool? At other times it was quite hot with low levels of CO2, while yet at other times, it was hot with high CO2 or cold with low CO2. Does you physical model explain all these as well. If not, WUWT?
that’s all for now.
Ira
Interesting approach. I always enjoy your posts.
As you tune this model, one factor should be considered along the lines of your number 6.
Since you are doubling all greenhouse gasses, I begin to loose confidence as to the validity of the model.
In reality if we double the water vapor would not the increased clouds significantly reduce the amount of energy that reaches the earth in the first place? And possibly cause cooling, as well as other impacts since a lot of things on earth depend on the sunshine energy, including trees etc.? Ideally the model needs to consider only doubling the CO2 which is more complex.
I have no trouble believing in the basic so called “greenhouse” effect as long as we admit the actual Physics may be different than an actual greenhouse.
For example we know that clouds significantly reduce the energy arriving here just by realizing the reduction in radiation reaching our body when a cloud suddenly passes over head on an otherwise sunny day. Unfortunately we cannot sense the effect of any change in CO2, partly because it does not filter out incoming sun energy and probably because it’s presence is so small Similarly I cannot personally detect the claim that CO2 radiates energy back to us either day or night.
Similarly we also know that on a cloudless night the earth cools down significantly faster and much more than when there are clouds overhead. Do we need any further evidence that at least clouds are a huge greenhouse gas? I can also believe that CO2 probably contributes, the question is how much and is it really significant given all the other factors like convection, wind, hurricanes, etc.
I tend to think that water vapor probably “rules” and Co2 may be a secondary effect at best even behind convection, evaporation, etc. Thr CAGW crowd woul be more credible it they acknowledged the fact the Water Vapor RULES.
Look forward to your improvement of the model.
“Ira Glickstein, PhD says:
February 20, 2011 at 7:53 pm
Yet, the longwave radiation that happens to be emitted downward from the added GHG does have to pass through more dense GHGs so some of it will be absorbed and re-emitted upwards. If any WUWT reader actually knows, please tell us. advTHANKSance!”
As you know of course, all gases, including GHGs are more dense as we go down. However I think the biggest thing that needs to be considered is that above the cloud layer, H2O has a very low concentration, so the CO2 above the clouds probably would “see” very little downward radiation hit Earth due to the sudden increase in H2O. At least this would be the case where absorption bands between CO2 and H2O overlap. Does this make sense and at least partly address your question?
Dr G.
On further reflection, I think that you have got the cart before the horse.
Step 1 (horse) you need to explain what the base line was, betore human CO2 emissions began – normal variability. Then you need to explain what has happened since and how much (if any is not due to normal variability).
Step 2 (cart) you should then examine all the competing explanations for what you have found in step 1 and state how well each explains any change that you have found. At that point and only at that point, you can introduce the particular physical laws that you have been explaining, as one possible explanation.
commieBob says February 20, 2011 at 8:29 pm
Nothing wrong with that per se. Now lets suppose some dodgy builder leaves out the vapour barrier on the inside and uses permeable insulation like normal rock wool. What do you suppose the temperature gradient through the insulation will look like now with normal household humidity levels if the dew point falls within the insulation (never mind the damage it will eventually do)?
Until someone shows me otherwise, I maintain water rules the thermosphere – it’s a heat pump running at half throttle with a hunting governor (clouds) and a massive heat sink under it. Please, why can’t these discussions for once address what happens radiatively at and above the thermopause? Earth does not present a solid radiative surface, it becomes increasingly rarefied and eventually physically stratified by molecular weight with elevation. Does simplistic application of radiative physics therefore still apply?
Dr. Glickstein, your thought experiment contains a serious error, and as such derives a false conclusion.
Although your thought experiment does fulfill the conservation of energy, it violates the conservation of momentum principle. Specifically, the blue slab that absorbs purple balls does so without moving. There is an action and no reaction, which means the momentum of the purple balls has been destroyed. However, the momentum of the half size balls that strike the ground is absorbed causing a force on the scales. You simply cannot destroy momentum in one instance and include momentum in another, this leads to a false conclusion.
To fix this thought experiment, you need to attach poles from the blue slab to the earth. When a large purple ball strikes the blue slab, tension is created in these poles. This tension creates a force that is exactly equal and opposite to the force generated by the half size balls striking the ground, i.e. Newton’s third Law. This means there will be no increase on the scales.
To leave out the reaction of the blue slab, to leave out the poles attaching the blue slab to the earth, and to leave out the counter balancing force on the earth means your conclusion that the scales will increase is false.
Dr. G.
First an apology – as usual my poor spelling and poor typing have again made my questions in my last two comments, even more difficult to understand than usual.
Second, it has just occurred to me that you have been talking about doubling GFC’s purely by increased human CO2 emissions.
Now that seems rather an odd way to approach the subject.
My understanding is that H2O represents between 0% and 4% of the atmosphere on different days and different places. In contrast CO2 and the other GFC’s make up only a tiny fraction of H2O’ contribution, bearing in mind that some of these have a more powerful effect that H2O.
Then you apply the logarithmetic effect and the fact the human emissions are only a part of total CO2 emissions. To that add the unknown (or at least un-agreed) reaction of H2O, clouds and so forth (positive and negative feedback). Well…
Perhaps the horse is not yet broken in, nor at all willing to drag your cart along.
(If you like my physical model of the task before you to simply explain the climate.)
An analogy, Ira Glickstein PhD, is supposed to ease the understanding of a problem, not make it more difficult.
You – and Willis Eschenbach when he starts ‘thought experimenting’ – just replace a relatively straightforward physical phenomenon with a complicated system with quite different physical properties. As a result you have now got many of your commentators worrying about elasticity and the various conservation laws – all of which has nothing to do with the ‘greenhouse effect’.
The greenhouse effect in essence is a simple, two step argument:
– CO2 (like a number of other gases) absorbs long wavelength IR. Any lab with a standard spectrometer can demonstrate this in under 30 minutes. What is to doubt?
– Such ‘greenhouse’ gases in the atmosphere therefore absorb long wavelength IR from the Earth’s surface. This heats them up, followed by all the consequent and well-known thermodynamic processes (radiation, etc.).
Now, the magnitude of this effect for particular greenhouse gases, the strata of the atmosphere that are affected and the resulting effects on our immensely complicated atmospheric system – that is the debate. To which, Ira Glickstein PhD, your analogy contributes nothing.
My response to Anthony’s appeal for suggestions for the future of WUWT: keep Ira Glickstein PhD in the cupboard under the stairs and don’t let him out without serious peer review. Publishing this kind of rubbish just exposes you to ridicule.
How does this re-heating of the earth by GHG, initially warmed by the same earth, go with the second law of Thermodynamics?
Just asking…
Greenhouse effect is simple indeed.
Ira, however, follows the wisdom: “Never choose a simple solution, if there is a way to make the things complex and beautiful”.
Great explanation for the day-time, but what happens when the sun goes down? What happens when the sun is cooler? (Why do greenhouses need heating in the winter?)
As with most analogies the compromise needed to create them looses a lot of the detail and the detail is key here.
“Why don’t we fill greenhouses with CO2?” – DocMartyn
We already fill greenhouses with the essential plant and planet nutrient CO2, and it works great growing us lots of yummy nutricioius food!
“For the majority of greenhouse crops, net photosynthesis increases as CO2 levels increase from 340–1,000 ppm (parts per million). Most crops show that for any given level of photosynthetically active radiation (PAR), increasing the CO2 level to 1,000 ppm will increase the photosynthesis by about 50% over ambient CO2 levels.
…
Carbon dioxide enters into the plant through the stomatal openings by the process of diffusion. Stomata are specialized cells located mainly on the underside of the leaves in the epidermal layer. The cells open and close allowing gas exchange to occur. The concentration of CO2 outside the leaf strongly influences the rate of CO2 uptake by the plant. The higher the CO2 concentration outside the leaf, the greater the uptake of CO2 by the plant. Light levels, leaf and ambient air temperatures, relative humidity, water stress and the CO2 and oxygen (O2) concentration in the air and the leaf, are many of the key factors that determine the opening and closing of the stomata.
Ambient CO2 level in outside air is about 340 ppm by volume. All plants grow well at this level but as CO2 levels are raised by 1,000 ppm photosynthesis increases proportionately resulting in more sugars and carbohydrates available for plant growth. Any actively growing crop in a tightly clad greenhouse with little or no ventilation can readily reduce the CO2 level during the day to as low as 200 ppm. The decrease in photosynthesis when CO2 level drops from 340 ppm to 200 ppm is similar to the increase when the CO2 levels are raised from 340 to about 1,300 ppm…. The level to which the CO2 concentration should be raised depends on the crop, light intensity, temperature, ventilation, stage of the crop growth and the economics of the crop. For most crops the saturation point will be reached at about 1,000–1,300 ppm under ideal circumstances.”
http://pathstoknowledge.wordpress.com/2011/02/20/real-benefits-of-an-enriched-co2-atmosphere/
Not bad at all Ira, you did a fairly good job of “people talk” to try and explain “the greenhouse effect”. It is really difficult to get through that the greenhouse effect has nothing to do with a greenhouse. Don’t worry about the Physics Major, he doesn’t understand “people talk”and wanted to show off his ignorance. Have a good one. pg
Ira, Possibly another 2 stupid questions. Could you firstly, explain to me why the temperature difference is significantly greater between day and night in the dry windless desert than it is in the humid stormy tropics and secondly, has the desert day/night temperature difference changed over time in accordance with climate modelling .
Ira, I think you alluded to it by the generic manner you addressed GHG’s versus singling out CO2 as one of many constituents (N2, O2, H2O, etc.) of the atmosphere but we need to get down to brass tacks here. Isn’t the real issue here the “density” of the atmosphere acting as an insulator that determines how much heat remains on a planetary body? If Venus’s atmosphere were pure Nitrogen versus CO2 with the same 90 bar pressure wouldn’t it be exactly as hot as it is now?
In fact, the only difference if there were any at all would be due to the physical property of specific heat of N2 (.18 Btu/lbsF) versus the specific heat of CO2 (.16 Btu/lbsF)? http://www.engineeringtoolbox.com/spesific-heat-capacity-gases-d_159.html Note: the specific heat given here is at 1 bar, not 90 bar but you get the point.
And wouldn’t that difference in specific heat be overcome by the wave lengths absorption ability of N2 versus CO2? http://www.iitap.iastate.edu/gccourse/forcing/images/image7.gif So if CO2 is not an absorber of UV or visable light but mostly of infrared then it stands to reason CO2 is only slowing down the rate of radition back to space just as Nitrogen is working to capture and hold it longer before radiating it off at infrared wave lengths. http://brneurosci.org/co2.html Given that there is vastly more N2 in the atmosphere than CO2, CO2 on a molecule per molecule basis can not in any way given its trace amount in any significant degree affect the temperature of the air much less get out of the error bar of a scientific calculation when dealing the heat balance of the planet.
So isn’t the whole issue really revolving around how dense the atmosphere is at any given time and has atmosphere during the latest warm spell been denser than say in the 1970s during that cold spell? As Anthony pointed out some time ago, when looking at the temperature profile of Vensus, where the atmospheric density reaches one bar in the atmospheric column, the temperature is nearly the same as Earth’s. Which in itself is remarkable given Vensus gets double the insolation of Earth due to it’s closer orbit to the Sun.
I am not a radiative physicist, so please bear with me. Infrared is energy of a certain wavelength, this hits a co2 molecule and is then instantly re-emitted, and the direction of emission is random, or does it re-emit at a 90 right angle to the incoming direction on a 360 degree plane? I assume the latter is correct, like light hitting a mirror?
Either way, it would then hit another particle below and bounce back only to hit others. There will be more particles to hit closer to the surface and less above so the energy isn’t trapped forever and eventually is emitted to space. The time is takes for the infrared energy to make its way through this tortuous path creates a back log of infrared energy which causes heat to be trapped. Correct?
My last question would be, does the net flow of energy have an effect on the direction of emission? A stone thrown into a still lake casts a perfect circle, but cast into a fast torrent the circle is emitted only forwards, due to the net flow of energy – does this analogy apply to the atmosphere, or does it not – as photons of energy cannot collide with each other but only interfere? Could upwards convection affect the emissive behavior of co2 and other GHG’s? or is it the otherway round, where the extra infrared energy results in increased upwards convection?
One issue I have with this sort of analogy is that 50% goes up and 50% comes back, I doubt its that simple in reality. Throw a stone in a still pond and its creates a circle, 50% one way, 50% the other, but if there is a net flow of water there is no longer a circle cast, and the stronger the flow of energy the more skewed it is on one direction, and when the flow of energy becomes supercritical, there circle is emitted in one direction only. I suspect this is more like the reality, as if two particles hit each other, one going upwards would have more speed and therefore anything emitted backwards is more likely to be ‘knocked’ back up then the other way around ( I hope I am explaining myself here!).
Any thoughts or views on this or is the net flow of energy to small an effect? I am interested to know if this has ever been considered, or is the greenhouse analogy of 50% one way and 50% the other a simplification to keep it simple? i.e. avoid difficult calculations that were not possible during the theories conception?
Graeme says (February 20, 2011 at 8:54 pm): “But a colder surface can’t radiate to a hotter surface…”
Ask yourself this question: As a sphere with a temperature, the earth radiates infrared energy in all directions. Does it radiate any of this energy at all in the direction of the sun, a much hotter body?
Sounds plausible until you realise that Atmospheric CO2 is not plentiful enough to have the stated effect.
Atmospheric CO2 = 0.034% Now try to imagine a box filled with one million smaller boxes. Now picture 390 boxes are CO2 molecules spaced evenly throughout the remaining 999.610 boxes. Now double the number of boxes to 780 and again imagine them spread evenly throughout the remaining 999210 boxes.
The few CO2 boxes within the larger box cannot have the proposed ability to both absorb, store and pass on all the solar radiation in the form of heat to different boxes each with their own particular absorption ranges which do not match the huge majority of boxes surrounding the CO2 boxes, only a fraction of the energy will make it through all the atmospheric obstructions. The proposed model assumes that solar radiation flows constantly with no interruptions through the other boxes and into the CO2 boxes which then absorbs this constant energy and passes it onto the surrounding boxes in the form of heat. This is not the case, the solar energy entering the atmosphere is not constant and the CO2 boxes can only absorb a narrow band of the incoming radiation which it cannot both store and emit through the other boxes which do not store or emit the same energy and when there is no incoming solar radiation to sustain the proposed action. If this were the case the nights would have become warmer and warmer until the night was as warm as the day and the planet would just another Venus and as dead.
In reality only a small proportion of the solar radiation band relevant to the CO2 boxes actually reaches them through the other boxes which obstruct the passage of this non constant radiation and not all of that is absorbed and here I think is the error. It is assumed that all the solar radiation from relevant absorption band makes it to the CO2 boxes through all the other boxes and does this constantly with no loss and if it did the model might be correct, as it is there are tens of thousands of other boxes between each CO2 box so the absorption and the storing and the re emitting of this narrow band cannot be total or anywhere near total and the incoming source is not constant nor does all all the solar radiation actually make it the CO2 boxes, it would only be a proportion the rest being intercepted and dissipated beforehand. The model also does not take into account dust and water in the form of clouds which both hold great quantities of CO2 and which takes it directly and quickly into the carbon life cycle at ground level and uses it up and none of this directly absorbed solar radiation is taken into account in the model. Its obvious that much of the remaining solar radiation absorbed by atmospheric CO2 is quickly and efficiently used up by the planets biomass cycle. I suppose that if you estimated the amount of urine produced each day by all the creatures of the earth and worked out how much CO2 makes its way through this biological process and how much of the proposed heat retention is taken out of the atmosphere by this process alone it would be no small amount!
While the model itself is viable it does not account for variables and other factors, it assumes a constancy of input and a far greater net absorption and conversion than is the case, nor does the model take into account the amount used and sequestered by earths prolific biomass. Imagine that every living thing that uses CO2 is taking energy directly from the solar radiation saturated atmospheric CO2 and using that energy within the CO2 molecule and this is something that the model does not take into account. We are not talking about a small amount either, the amount directly consumed and translated by the planets biomass is huge. The model might be of some greater use when all the other factors are included.
Ira thanks for the excellent analogy. While some suggest to put you in the dungeon under the steps Ira to censor you, I say the article is a good introduction to the first part of the issue.
I find when teaching with analogies it’s always best to add in the scientific language so people get familiar with it while learning the concepts; at the end would spruce it up. Something like the following might work, although we’d want verifiable empirical observational data and numbers to substantiate it:
“The greenhouse effect in essence is a simple, two step argument:
– CO2 (like a number of other gases) absorbs long wavelength IR. Any lab with a standard spectrometer can demonstrate this in under 30 minutes. What is to doubt?
– Such ‘greenhouse’ gases in the atmosphere therefore absorb long wavelength IR from the Earth’s surface. This heats them up, followed by all the consequent and well-known thermodynamic processes (radiation, etc.). Now, the magnitude of this effect for particular greenhouse gases, the strata of the atmosphere that are affected and the resulting effects on our immensely complicated atmospheric system – that is the debate.” – Richard Smith
Oh, it would actually be really great to see the afore mentioned 30 minute experiment in a video. I wonder if such a video exists or if one can be made by some enterprising skeptical scientist? What would it take to replicate such an experiment at home or at school?
Science “believed” or “accepted” is not much better than religion. Science replicated and verified (or refuted) is knowledge gained and infinitely better than “belief” of any form.
You’ve forgotten that before most of the excited CO2 molecules can re-emit the quantised IR energy, they’ve lost it in collisions to O2 and N2 molecules. The heating effect on the air is shown by the mirage effect.
That heat is convected to the tropopause where it can radiate to space at night!
See this: http://notrickszone.com/2011/02/11/is-co2-warming-a-mirage/#comment-15200
AJB says:
February 20, 2011 at 10:16 pm
“Until someone shows me otherwise, I maintain water rules the thermosphere – it’s a heat pump running at half throttle with a hunting governor (clouds) and a massive heat sink under it.”
+1
@pwl
“Oh, it would actually be really great to see the afore mentioned 30 minute experiment in a video. I wonder if such a video exists or if one can be made by some enterprising skeptical scientist? What would it take to replicate such an experiment at home or at school?”
Er… A spectrometer?
CO2 is not collected in simple layers.
The vertical distribution of CO2 in the air in a perfect mix would be equal from the ground upwards. This means you would measure 380ppm at sea level and in the mountains.
However, CO2 is heavier than O and has the tendency to collect more in the lower part of the atmosphere. This means that the concentration is higher on the ground than higher up in the atmosphere.
The main natural sinks are the oceans and plants and other organisms that use photosynthesis to remove carbon from the atmosphere by incorporating it into biomass.
Hi great diagram for a layman to have a stab at understanding the greenhouse effect.
Only one question. How much of that affect is contributed by manmade C02?
Reply to Joe 12.12 am.
CO2 is effectively perfectly mixed in the troposphere. H2O falls with height because of thermodynamic issues.