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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Most of that short wave energy that goes into the oceans is transmitted to the atmosphere in the form of water vapor rather than radiation. That evaporation causes up drafts forming clouds that can carry that energy to the TOA where there is very little GHG to split your blue balls. The driving force for that convection is the difference in temperature between the sea surface and TOA. The rates of evaporation and condensation and freezing and thawing are controlling the rates heat is lost to space. CO2 follows these processes. Warming seas give off CO2. Cold clouds absorb it and carry it up and away or return it to the ocean in rain. CO2 is going along for the ride like a flee on an elephant. Think about the difference in magnitude between the heat of vaporization of water and the heat capacity of air.
My understanding is that all the energy supposedly absorbed by CO2 gets absorbed in the first 15m. If you double the amount of CO2 it gets absorbed in the first 7.5m, and then if you double it again it gets absorbed in the first 4.75m.
Since there is no real difference if the atmosphere is heated int he first 15m, 7.5m or 4.75m, CO2 makes ZERO difference. Unless of course you removed all Co2 fromt eh atmosphere – thereby killing all plants.
The infrared activity of the troposphere keeps tropospheric temperatures and surface temperatures cooler than they would be otherwise, not warmer. The infrared activity of the troposphere is what allows the troposphere to cool to space. That keeps surface temperatures cooler, not warmer.
If the troposphere was transparent to infrared energy and incapable of absorbing or emitting infrared energy, the troposphere would still be warmed via conduction with the planets surface, but it would not possess any means of ever cooling.
Under those conditions, tropospheric temperatures and surface temperatures would be very, very hot, day and night, year-round, forever.
Why on earth any rational person would believe that the infrared activity of the troposphere results in some kind of mystical, magical “greenhouse effect” that keeps surface temperatures warmer than they would be otherwise I cannot imagine. Perhaps it is some kind of leftover from the drug culture of the 1960’s or something, I don’t know.
Go figure.
This “explanation” makes no sense at all. Explain why more heat is not deflected back into space on entry IF the GHG is so good that it deflects heat FROM the Earth back to Earth.
Foe anyone not wishing to take Ira’s post on its merits, I suggest you stand before a large class of students and explain how the troposphere works. You have 2 hours. The next day return to those students and ask them to write out an explanation from only what is in their head. Let’s assume that class has only 80 students and they have 2 hours. When they are done you get to read all they have concocted and grade it. Come back and tell us how that works out.
All those balls would break the glass in a greenhouse.
Perhaps it would be better described as a “bounce house” effect?
Dunno.
One thing – all the wind/air currents blowing those balls around can’t be making the “bounce” any easier to predict or sometimes, perhaps, even discern. (OK, make that two things.)
@DocMartyn says:
February 20, 2011 at 5:13 pm
” Why don’t we fill greenhouses with CO2?”
Actually, it is common practice to increase the level of CO2 in large commercial greenhouses. It seems that it makes the crop in the greenhouse grow faster. Imagine that! Just use your favorite search engine to look for the use of CO2 in commercial green houses.
Ira:
Thanks for the opportunity to comment.
In my view, “the atmospheric greenhouse effect” is a misnomer and piece of propaganda. That there is an “effect” implies that there is an “efficient cause.” Tacking “the” onto the front of the phrase implies the uniqueness of the effect, given the efficient cause.
The “effect” is an increase in the equilibrium temperature at Earth’s surface. The “efficient cause” is an increase in the concentration of a greenhouse gas in the atmosphere. The equilibrium temperature is not an observable, making the claim of the alleged cause and effect relationship scientifically nonsensical.
To argue that a complex system can be reduced to cause and effect relationships is the logical error that is known as “reductionism.” In using the phrase “the atmospheric greenhouse effect” as though it were a fact, one makes this argument.
I get upset when I see “The greenhouse effect heats the earth because greenhouse gases absorb outgoing radiative energy and re-emit some of it back towards earth.” repeated. This is totally false. All the re-emitted radiation back to Earth represents is the RESULT of the Earth being heated by atmospheric greenhouse gases, NOT THE CAUSE. The atmospheric greenhouse gases act as a radiation partial insulator, but since the air transports the absorbed solar energy (by the atmosphere, ground and oceans) freely up by evaporation and convection, along with some net radiation, there is no heat trapping. The result of the radiation partial insulation is to raise the location of radiation to space to a high altitude rather than directly from the surface. The lapse rate caused by basic atmospheric dynamics (adiabatic wet lapse rate =-6.5 C/km) does the rest. The effective average location of outgoing radiation is about 5 km, so the lapse rate times 5 km=-33 C. Note that the higher ground and thus air temperature near the ground then cause the higher radiation levels. Also note it is ONLY the difference between up and down radiation that causes heat transfer, so both being bigger is just the RESULT not cause of heating.
According to the law of “Conservation of Momentum” your analogy is wrong!
After the initial absortion by the CO2 of the longwave radiation from the earth, most of the re-emitted longwave radiation should be emitted upward into space.
I see I did not address the point: does more CO2 increase the atmospheric greenhouse effect? The answer is yes, it slightly raises the location of outgoing radiation to space, and thus the lapse rate times the slight increase in altitude would raise the ground temperature. The main question is how much, and this is not clear. My best guess based on historical and recent data supports a raise of between 0.1 and o.5 C per doubling of CO2, with cloud negative feedback being a major controlling factor. This is much smaller than the CAGW estimates.
DocMartyn: You are correct, see my CO2 is Plant Food (Clean Coal, Say WATT?) for a potential way to use that CO2 to grow more food.
Brego,
The surface temperature would go to 255 C and the atmosphere would go to 255 C for an optically transparent atmosphere and a uniformly heated and cooled planet. However, since only one side is heated at a time and it rotated, and storage and transfer of energy from one location to another occurs, the problem is more complicated (as it is for Earth). It would NOT get hot.
Ira,
I think you’ve done an excellent job. The quibles about missing details (including your own list) are really insignificant. The main concept is intact, and in terms of providing an entry level explanation that can be easily visualized, I think it is excellent. Anyone with a reasonable understanding of your article ought to be able to walk up to a white board and explain it free hand to someone else in a matter of minutes. That’s the big piece we’re missing in the climate debate, widespread knowledge of the basics.
What I do think needs to be added doesn’t change the basic explanation at all, but I think a couple more graphics would really be beneficial, in fact answering some of the questions already posted in this thread.
The first regards what really happens as CO2 is added. The “shells” you illustrate help with the over all concept and provide for a basic approach from a math perspective as well. But I think once a person has that in their head, there ought to be one showing several examples of the actual path any given photon might take. For example, one going straight out to space, one going half way up then one quarter down then sideways… the net AVERAGE might be reasonably well represented by the concept of shells, but in reality there’s gadzillions of photons travelling at the speed of light and any one can change from any direction to any direction at any point in the atmosphere.
The next one I don’t have such a good handle on, but it needs both your shell explanation and the randomness of the photon paths explained first. How does one illustrate both those concepts at once, and in the gadzillions? I tried to create a graphic once but never finished it. My idea was to show the photons in the atmosphere as a shaded gradient. The gradient would be darkest at the bottom where the LW photons originate, and lightest at the top. BUT there would also be a darke fuzzy stripe somewhere in the middle. Since we’re trying to understand both the possible paths a photon might take to leave the atmosphere AND how the concentration at any given point changes, the dark stripe in the middle would represent that area of the atmosphere where downward bound LW and upward bound LW have a peak concentration.
From there is starts to be a lot easier to answer a lot of questions. Like someone;s question above about all the LW being absorbed within a certain distance, so what difference does it make? Another comment I hear a lot pertains to water vapour being so much stronger and absorber of LW that the CO2 doesn’t matter. You can show that it does by illustrating water vapour as being very “thick” at the bottom of the graph and very “thin” at the top because water vapour declines with temperature which declines with altitude. So CO2 is nearly insignicant close to ocean surface, but increases in signicance with both altitute and latitude.
No such thing. You cannot “back-radiate”, therefore, you cannot have a “greenhouse effect”
Gives me a better understanding of the conceptual difference between energy and temperature: how in the presence of the same amount of energy, an increase in GHG raises the temperature. Well done. Much appreciated…
CCR
Sorry Ken, but, although the nighttime Earth is cooler than it is in daytime, it remains warm enough to continue emitting longwave radiation. If not for the GHGs in the atmosphere (not just CO2 but also water vapor and other GHGs) it would be a heck of a lot cooler at night and, over the entire day and year, the Earth would be too cold to support life. Those are the facts. Please do not allow the distortions of the facts about CO2 sensitivity and the temperature record by the official climate Team lead to an equal and opposite reaction in the wrong direction.
Oh Ira, no look what you have done? You started the ball rolling, that’s what you have done. ☺ I’ve been waiting for someone for a long time to get that same visual. I’m terrible at art but your the man! And up from I don’t seem to be able to write very smooth and congenial but it is all meant that way all from a small injury from years ago, got my words but not my mind thank heaven!
Hope this post lingers long enough to discuss. Think after reading this we might.
I for one don’t need the drawing, I’ve had that very thing in my mind, but I do need it for others to see the complete picture placed in neat graphics so everyone can follow in step. By the way, fantastic graphics. I’ve been scanned.
Some additions/factors on your six points:
1. ½ up, ½ down — By the end of your series I sure hope you will cover the curvature of the Earth for this is the topic, this division is not real by 1%-2%. This correction is strictly geometric being a sphere and I have raised that in comments at least three times here in the past month’s and no one seems to get it or at least no one comments one way or the other. That factor favoring upward is enough alone to be Trenberth’s “missing energy” thought it probably isn’t per se.
2. The radiative window — Ok with that.
3. Thermals & evapo-transpiration — Ok with that for all of that energy ends up in the atmosphere just as if it had been radiated upward and absorbed high above so no real difference when only speaking of radiation.
4. Shells — Really it integrates as an infinite number of shells.
5. Doubling & H2O — I’ve got a problem here. That feedback to H2O is still up in the air and even though I feel it’s negative could you just set it for a while at a mean of 2½ % (Wikipedia says 1%-4% so I’m pick the middle, you might want some other) till the very last possible correction to your sequels? Please?
At that two and one-half percent concentration in the lower troposphere works out to be 62 water vapor molecules for each carbon dioxide molecule.
6. Albedo & reflection — Once again, could any possible cloud corrections wait till the end? Please?
However Ira, there is one huge error here on graphic two.
You can’t have double layers the way you drew it. Your first drawing is near perfect because ½ purple goes down, ½ purple goes up, same for ¼ and so on. Perfectly symmetrical. As should be.
But then you do what all AGWers would love to do but it violates pure integration logic, you add a new layer only on the top so look what is going up… always ½ of what goes down. That is you then have ½ down and ¼ up, ¼ down 1/8 up, and so on. You add more layers and quickly there is basically NO energy going up, all down. Do you see that?
Yes the atmosphere is an infinite number of layers but it really should be drawn that way on you very first graphic. But that is quite impossible right? So we are back to your imagination a bit.
Then what really happens when you double the CO2? You have double the molecules that *can* absorb but you have to replace each purple by two with ½ the energy. Double the balls but half their size. Conservation of incoming energy. Now that is correct. You see we have NOT increased the energy from the sun, we have only made it so each CO2 will only have ½ the energy it absorbs compared to the first example but the overall process is identical. Best to view the balls as some picked groups of photons, not individual ones. See that?
That is really what is buried in the words of Miskolczi’s work. I’m not propping him up but his paper did do one great thing, it measured the, how do I say it, average clear-sky Planck weighted IR optical thickness to a constant. That is basically the window. He places no cause on the recent century rise but it does become clear (took me months to see it) that doubling the carbon dioxide OR water vapor OR any other GHG will have no effect at all.
Once again, that is because solar input is rather constant and the energy there is divided by the *available* molecules. If you half the molecules (half the concentration), each molecule will be double busy absorbing photons and 90% or so will thermalize, bi-directionally. If you double the GHG molecules (double the concentration) each molecule will be having it easy for it is working half as hard absorbing photons. Probably a better way to word it but that’s the best I can do. Can you see it yet?
No wonder we need simple graphics, Einstein was right again! This is my third attempt to have at least one person seated in physics to see this. ☺
The more time goes by the more quantum physics changes and go away from being what what Einstein didn’t like about it. It looks like Einsteins opinion of quantum physics just might have been right!
Frank, that is not a stupid question. If we doubled ALL GHGs (not just CO2 but also water vapor, etc.) the Atmosphere would not double in height as it does in my simplified analogy. It would mainly increase the density of GHGs in the Atmosphere. Many scientists who know this stuff far better than I have done the analysis and they all agree that successive increases have a logarithmic effect, which my physical analogy also has. That means that doubling GHGs will increase warming, but by successively smaller increments, even considering just the radiative effects alone. (In the real-world, of course, if warming leads to more water vapor and if that leads to more daytime clouds, possibly more precipitation and thunderstorms and so on, the additional warming will be reduced, but, there will still be some warming with increased GHGs).
A way to think about the logarithmic effect on radiative transmission is to imagine you have a very sunny window. So, you install sun curtains that block 80% of the sunlight coming in, so the sunlight coming in will be 20%. If you then add another layer of sun curtains, that will block 80% of that 20% so the sunlight coming in will be down to 4%. Yet another layer of curtains will block 80% of that 4% and only 0.8% will come in. Of course, GHGs in the Atmosphere are not exactly like sun curtains, and there are other effects that reduce GHG warming, but the idea is the same. Each additional increment of GHG causes less additional warming than the previous increment.
Good explanation – but only if the concentration of the greenhouse gas is vanishingly small so that it’s absorption of the infrared is near zero. Doubling of the gas concentration would essentially double the absorption. Things are not that simplistic when the absorption bands are nearly saturated, like CO2.
At about 300 ppm CO2 there is only enough room in the atmosphere for a total of 5% more absorption of infrared. That is THE physical limit of the atmosphere density & depth and those additional 5% blueinfraredenergyberries occurs at 1,000,000 ppm CO2, yeh 100% CO2. Okay, so I concede that figure 3 is representative of 300 – 400 ppm CO2.
In doubling CO2 from 300 to 600 ppm (I know were at nearly 400 ppm now but my 95% CO2 band saturation information is at 300 ppm) the additional blueIRenergyberries that must be added to figure 3 to give figure 4 is only 2.5% so figure 4 grossly exaggerates what doubling of CO2 would do. This means that the scale would only increase to 1.025, NOT 2. And looking at the quality of the scale, I doubt if an additional 0.025 could even be detected. It would be hidden in the uncertainty.
Finally, I see a number of commenters above are now raising the sphere factor!
It’s a good day! (but a long, long day today)
HaroldW, you may be right, but only if the downward balls from the upper Atmosphere layer in my physical analogy could fall directly on the Earth, without having to go through the lower Atmosphere layer. In my analogy, however, those balls have to go through the lower layer and only half of them will make it on the first shot. That is why I made the meter stop short of “3”.
The real-world situation is different, of course, because additional GHG increase density and don’t add another layer. 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!
RayG, I think you are missing DocMartin’s point. He is not talking about inputting greenhouses with CO2 to help with plant growth, which everyone knows is common practice. Rather, is anyone putting CO2 in greenhouses to make them warmer?
FatBigot says:
February 20, 2011 at 6:21 pm
What happens in those parts of the world that don’t play baseball?
Soccer balls, footballs, hockey pucks, tidleywinks, marbles, snowballs, cow flops, etc. :^)