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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A bouncing ball absorbs and re-emits energy… so the analogy is pretty good… when the balls hit the earth they bounce off in different directions… but they do bounce off… all the greenhouse effect can do is slow down the speed at which the balls bounce off through the atmosphere of the earth… a bit like wind resistance… the balls do not endlessly bounce backwards and forwards between the earth and the atmosphere… the balls just bounce off the earth through the atmosphere at a slower speed… so basically the greenhouse effect is just balls…
@Joe Kirklin
“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.”
Er… Winds? Downdrafts? Convective lifting? Stratospheric insertion (jet aircraft)? Jet streams?
Hi Ira,
I fully agree with your simplification to explain the GHGs effect, well done.
I just have a question about your reply at February 20, 2011 at 7:24 pm to what Ken Coffman says at February 20, 2011 at 5:15 pm.
You wrote:
“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.”
How do you know that the atmosphere “it would be a heck of a lot cooler at night”? Do you believe that non GHGs couldn’t keep the Earth and the atmosphere warm via the thermodynamic exchanges at all?
I mean, if the atmosphere was made only of nitrogen I don’t believe that the ground temperature will be the same as the atmosphere wasn’t there at all.
The same “jumping pop-corn” analogy could be done for the non GHGs molecules which “bumping” on the ground “smooth” the ground thermal agitation during the day when the atmosphere is cooler, and “enhance” the same ground thermal agitation during the night time when the atmosphere is warmer. From my point of view this effect should exist and should be weighted against the sole radiative effect to establish how much the GHGs affect the Earth temperature. I also haven’t find any proof that an increase of GHGs in the atmosphere do not reduce the thermodynamic effect described above. It is my opinion that it could reduce the thermodynamic effect, and in that case it could be that the GHGs do not changes the Earth temperature at all, they could just change the place where the photons exits the system.
Massimo
Here is a problem I have with AGW. I think it is a true statement to say that if increasing CO2 since the industrial revolution has had an effect, then the recent record setting low in Bartlesville, OK would be impossible, since it is all radiative cooling. We shouldn’t be seeing record setting lows, and yet there it was.
I just realized something your physical analogy doesn’t take into account and someone else also refered to it, the earth being round. It’s more than being round though, it’s the amount of atmosphere at various points in the day that receive the Sun’s energy. Why is it that as soon as the sun is visable from the horizon at sun rise that the temperature doesn’t go to the maximum value as your analogy would imply? Because the amount of the air that the sunlight/energy has to travel through is GREATER, hence the energy is absorbed and radiated off into space at much greater amounts than directly overhead. Given that CO2 is NOT uniformly mixed in the air column but is greatest at sea level and given that greatest amount of energy transport to the ground is between 10 a.m. and 2 p.m. due to the sin of the angle because the earth is round, the only time that CO2 could possibly have an influence IF it even did would be only 4 hours per day. Your analogy as far as CO2 is concerned only works IF you discount the other 14 to 8 hours per day depending on the seasonal variation of day length. So not only is CO2 a non factor due to its being a trace gas, it has absolutely no effect due to its being a rarefied gas most of the day when the distance the sun’s energy has to travel is even greater through in the O2 and N2 volumetrically dominated atmosphere.
Being a trace gas, it is physically impossible for a CO2 molecule to collect and re-emit radiation from ALL or a substancial part of the N2, O2 dominated atmosphere at a ratio of 1 to .00034, to claim that kind of efficiency of heat transfer is simply magical.
Ken Coffman says: February 20, 2011 at 5:15 pm
On even numbered days, I believe this happens, but the effect is so small it cannot be measured. On odd days, I don’t believe this at all and think CO2 can only increase coupling to space (increase our cooling rate).
Ken, likewise I think CO2 has a significant cooling effect which is ignored … because it is an inconvenient truth that it does cool.
Everyone has heard about CO2 ‘s ability to absorb IR, but have heard about that its increased power of absorption is EXACTLY MATCHED with the increased power of emission. It’s a bit like saying a room gets cooler if you open the fridge … that’s the mind numbing stupidity of this “science”. Yes a fridge does make a room cooler (for a few minutes) and yes it does if you have a theoretical model that ignores one side of the equation.
Also, heat rises, hot air rises, the atmosphere is in constant circulation. The atmosphere is really part of the active cooling system of the planet, and increasing CO2 increases the rate of cooling because the sun-heated atmosphere is hotter than the bulk of space and the higher emissivity of the CO2 helps cool the atmosphere.
There is no question that heating and cooling of the earth are balanced (save the rounding errors), yet somehow people treat us as if the fridge door being open is cooling the planet!
We are constantly bombarded with nonsense diagrams with a minuscule sun heating the planet that is an object covering 6×10−5 steradians … where are the diagrams for the other 99.9995% of the sky which is at mind boggling -270C, or -455 Fahrenheit.
Come on guys! 99.9995% of the sky is super cooled, yet you are fixated by an “insignificant” (joke) little 0.0005%!!! (obviously the two are equal … but the point is the cooling effect deserves 50% of the coverage not the 0.0001% it seems to get (a
The theory of GHG’s assumes that heat loss is constant but it is not. It also assumes that heat adsorbed by the so called greenhouse gasses is re-radiated to the surface. It is not. The 2nd law of thermodynamics always applies so as temperature increases so heat loss increases. Also any energy adsorbed at height will only be re-radiated to the surface if it results in a temperature increase above that of the surface. This is questionable. Heat radiated is in all directions proportional to the temperature difference.
HaroldW says:
February 20, 2011 at 6:12 pm
Assuming the second layer also reflects half the balls downward (and lets the other half pass through into space), if you calculate the infinite sum, I think you’ll find the “2+” for the 2-layer model comes out to 3.
Ira Glickstein, PhD says:
February 20, 2011 at 7:53 pm
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″.
I have to side with HaroldW. The reading on the scale will be 3, even considering the interaction with the second layer. The reading on the scale comes from the incident (yellow balls) rate plus what comes down from the tier 2 (middle): Reading = I + R2down. This is the same as R1up.
Now
R1up=I+R2down
R2down=R2up=R1up/2+R3down/2
R3down=R3up=R2up/2=I
Doing the algebra, one finds R2down=2I. Hence, the reading on the scale is 3. (This way of doing the math accomplishes the infinite series for you. In the first example when the third tier is absent, the equations are just R1up=I+R2down and R2down=R2up=R1up/2=I, which gives a reading of 2.)
Well, instead of Trenberth arrows there are violet balls now, but still no proof how much the back-radiated IR actually affects the surface temperature. Let’s measure the rate of nigh-time cooling above the desert with balloons measuring the humidity up to 10km or something and observe changes with changing humidity. Or lets feed the climate model with the desert data, extremely low humidity and CO2 – I bet we would obtain unrealistically low night time temperatures. All those models ignore simple fact – that oceans, soil and atmosphere have heat-retaining capacity and all models just scale the mythical 33K effect onto theoretically calculated back-radiation, so no wonder the climate models are wrong; they are based on nonsense.
@RichardSmith
Er… Winds? Downdrafts? Convective lifting? Stratospheric insertion (jet aircraft)? Jet streams?
You are right and that is the reason why it is going up. It would not go up without it.
The layer of CO2 is the whole atmosphere und not just a ring higher up, as it is shown in a lot of illustrations. CO2 is all around you.
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.
Of course this would break the analogy if the real effect subject to the analogy was significantly impacted by the momentum of the photons .
It doesn’t .
Few people have in mind what the real proportions in the atmosphere are .
15µ photons go very fast and transport a huge energy at their scale what has for consequence that there are very few of them .
In 1 m^3 of lower troposphere air you have approximately 10^22 CO2 molecules .
In this same 1 m^3 you have approximately 10^14 photons 15 µ – assuming radiated power of 300 W , everything in 15 µ what is not exact but we only need an order of magnitude .
In reality there are less 15 µ photons than that number .
So there are 1 billion times more CO2 molecules than 15 µ photons in 1 m^3 .
Therefore few CO2 molecules will meet a 15 µ photon and as the CO2 molecules have a huge momentum compared to the momentum of the 15 µ photon , the total momentum of the CO2 layer is constant for all practical purposes .
The collisions between CO2 and photons are just a negligibly small perturbation of the total momentum .
This also explains why the 15µ photons have little chance to go very far when 1 billion hungry CO2 molecules are waiting for each of them .
Actually the process that exites the energy levels of CO2 in a much larger manner than CO2 absorbtion are the collisions with N2 and O2 .
There are much much more such collisions than the available 15 µ photons .
As for the validity of the analogy , the biggest problem I see is that “doubling” CO2 doesn’t consist at all in “doubling” the atmosphere height .
The latter stays approximately constant , just the density increases .
So the right analogy should be that the initially single layer splits in 2 layers what increases the number of purple balls by 2 . Of course as there is no conservation law for the number of photons (purple balls) , this may be confusing for some .
But now this problem of non conservation of number of photons has always been a big problem for mechanical analogies where one uses concepts like balls whose numbers generally conserve .
To those who make 2nd Law objections to radiating from cool to hot: the “Law” is about a bulk effect, a statement about NET transfer.
Two guys having a hose water fight. One has a garden hose, one has a firehose. (We’ll restrict both to spray rather than jet, just to take kinetic effects out of the analogy. 😉 ) Both get wetted, but the wetting of the guy with the garden hose is much greater. That’s all the 2nd Law has to say about ‘direction’ of NET heat flow.
Ira’s analogy suffers far more from ignoring the thermal transfer of received energy from CO2 molecules, orders of magnitude greater than radiative loss. And then a very little of that thermal energy cycles back to CO2 molecules, which radiate another minute fraction before losing heat in collisions, etc. This logarithmic decline is far steeper than the ~.50 described in the model. Further, each radiative emission cools the CO2 molecule, which then chills the atmosphere around it by collision absorption of heat energy. (The specific heat and mass of the atmosphere is much lower than that of the surface, so air temps swing far faster than ground temps, it should be noted. But rarely is.)
It is interesting that figures I recall seeing for Mars (which has 30X as much CO2 in its atmosphere, despite the low density overall) suggest that it is actually 0.1°C cooler than its blackbody temp. In any case, it certainly isn’t warmed much by the GHG effect.
Note to Don Shaw: clouds are not a gas, GH or otherwise. They are water droplets suspended by Brownian motion and updrafts.
_Jim says:
February 20, 2011 at 5:45 pm
tallbrokes wordpress page
Hi Underscore Jim. You scored under on spelling there. :¬)
Doc Martyn wrote: “Why don’t we replace the vacuum in Dewer flasks with CO2?”
Dewar flasks are made of metal that emit very little IR keeping radiation losses down. In order to block IR in the few millimeters available between the walls in a dewar flask you’d need to have a fairly high pressure of some efficient greenhouse gas. This would reduce radiation losses, but on the other hand you’d get heat loss through conduction and convection in the gas, and the latter would be far larger.
tb;
tallbroke is what they call you in Japan and China. Hearing is believing!
;┘)
DocMartyn says:
February 20, 2011 at 5:13 pm
“human beings are very smart, they can take any piece of scientific knowledge and turn it into technology, so not has no one[?] used the CO2 green house effect for anything?”
The ability of CO2 to absorb energy in the microwave part of the electromagnetic spectrum and emit it because of the quantum energy levels of the vibrational modes of the dipole molecule are utilized to make the CO2 laser. Probably the most common high-power laser in use for industrial and medical purposes.
Not to mention a measuring device for determining the atmospheric level of CO2.
RichardSmith;
If it is so simple, why is it that so few understand it?
Your own explanation boggles the mind. A simple two step process followed by the consequent well known laws of thermodynamics. Show me the computer code from any two climate models out of the 20 or so in the IPCC report that are the same on that score. If it was that simple, they would be.
Well if you take off the glass ceiling roof of your “greenhouse” than I’m on board, but then you’d probably loose the whole classic “greenhouse effect” and probably adopt a rodent problem. :p
Maybe it should be called the greenhouse affect in connection with temperature?
Some seem to like the analogy some seem to hate it. I am in the middle. I like analogies but the problem with this one is that it is not realistic enough to come to any conclusions about the effect of small changes and it is clearly not simple enough to convince people who believe the effect can’t exsist. I also worry that it seems to focus on radiation dynamics and not enough on the simple issue of how energy is radiated to space. Like some others I think the real world is actually simpler than the analogy.
I see the real world as follows:
1) For the earth to maintain a constant temperature averaged over the whole surface averaged over a whole year the earth has to radiate all the energy it receives from the sun over that time. If it does not the balance of energy will have to be stored in or released from something. This does happen in practice with ice and the oceans being the main reservoirs. But for a simple analysis this can be ignored as can the fact that my opening statement is not exactly true given that one cannot measure heat balance using averages without taking thermal capacity into account.
2) The radiation absorbed by the earth is dependent on its albedo (reflectivity) and the output from the sun. These can be considered constant to the first approximation but obviously cloud albedo is a hot topic at the moment (Svenmark).
3) All the energy lost to space is by radiation. If one looks at the satellite measurements of radiation from the earth you see that at certain wavelengths the radiation is characteristic of the temperature of the earth’s surface. This is particularly true for the 9 -12 micron ‘atmospheric window’. However particularly between 5-8 micron where water absorbs strongly and 14-18 micron where CO2 absorbs the radiation is characteristic of a much cooler body. There is no point discussing this because here we have one of the few cases in climate science where we have actual measurements to prove something.
4) The reason why the radiation at these wavelengths is characteristic of a body at a cooler temperature is because that is exactly what is happening. Radiation at these wavelengths cannot be radiated directly into space from the surface because these photons are easily absorbed by water and CO2 molecules. All the detailed arguements about absorption and re-absorption are largely irrelevant. The fact is that the actual amount of energy lost into space at these wavelengths is dependent on the altitude this finally takes place. The basic theory is that the higher the cooler and the less the radiation loss. The greater the density of water and CO2 the greater the altitude at which unobstructed radiation to space can occur. So it follows that more CO2 ought to lead to less radiation and, to a first approximation, it does. The measurements prove it.
5) Thus the presence of water vapour and CO2 means that less energy is radiated into space from within their characteristic radiation bands so the temperature of the earth’s surface has to increase in order for energy radiated at other wavelengths to increase to compensate. This is the warming due to the, poorly named, greenhouse effect.
However the devil is in the detail and this is where analogies do not help. As the concentration of CO2 has increased in recent years it should have been a simple matter to provide radiation measurements supporting the theory. However, the measurements I have seen are not convincing. At the very least the variation of outgoing IR on a month to month basis is huge compared with the small linear decrease that the CO2 increase should generate. Clearly there are other transient factors which dominate the actual radiation balance so could any of these act as negative feedbacks? No one really knows.
One of the biggest issues I have is whether the effective height that CO2 radiates is already above 16km in the tropics and 8km at the poles. These are the altitudes at which the tropopause starts. That is the altitude where temperature no longer drops as one goes upwards. The satellite pictures I have seen suggest it is. If this is the case an increase in CO2 would not automatically lead to reduced radiation loss. Indeed it could actually lead to an increased loss if there were more radiating molecules at the same temperature. To me this is a crucial issue. If the tropopause is not increasing in altitude (and therefore cooling) I do not think a further CO2 based warming effect is physically possible. It should be measureable but, like the outgoing IR measurements, if such a change had indeed taken place I think we would have heard about it by now.
RichardSmith, you are a bit harsh. Different people understand stuff in different ways. As is clear from a lot of the comments here, many people don’t understand how greenhouse warming works, and attempts like Ira’s are good. You obviously understand stuff differently, which is lucky for you….
Of course, if people don’t want to understand, they will find a way not to.
I haven’t the time to read all of the comments, but I’d like to say that Indur’s attempt to visualize the “Greenhouse Effect” of the Earth’s atmosphere is not much better than Willis’, and Willis’ attempt was just plain wrong.
Sorry.
The natural phenomena you explain is real–earth would be a very different place without the GHGs–dominated by dihydrogen monoxide, I might add. I doubt any thinking, serious scientist would deny it. However, the question becomes whether the increase in carbon dioxide will ever reach a tipping point beyond which earth’s climate spirals out of control and is irreparably damaged. Since per-historic levels of CO2 have been many times the current level, I say such a supposition is completely unfounded, flawed, even dangerous–their hypothesis is false. I read all sorts of specious arguments by warmers that we’ve already passed this “tipping point”, and see precious little evidence supporting said arguments–even though they say the evidence is all around us. I think they’re idiots.
I also submit that having a warmer earth is beneficial–to plants, to humans, and to other animals. I’m not at all convinced that forcing humans into a no-carbon lifestyle (do you catch the contradition in terms there?) will be benefical in any way whatsoever. Evil people are using scare tactics and selective science to thwart civilization’s most fundamental freedoms and foisting upon them elitist controls–all in the name of some false notion that CO2 is king of the GHGs.
It simply isn’t.
It’s as if these pre-eminent scientists are completely lacking in the ability to do a thorough systematic analysis–and they call themselves “scientists”. I call them “what–iffers”, and “if” is actually the biggest, most irresponsible word in the English language. That makes them irresponsible scientists.
Good questions. In the daytime, the humid tropics have more clouds than the dry desert, and they tend to block and reflect back to Space some of the shortwave radiation in direct sunlight, which would limit the increase in daytime temperatures. At night, the clouds in the humid tropics absorb and re-emit longwave radiation back to the Earth which has the effect of increasing nightime temperatures. Relative lack of clouds in the dry desert exposes the surface to more daytime warming and more nightime cooling. I do not know the answer to your second question.
Joe says:
February 21, 2011 at 12:12 am
“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.”
We DO measure 380ppm at sea level AND in the mountains.
Convective and turbulent mixing VASTLY outweigh the effect of gravity.
And the speed of air molecules at room temperature is about twice that of a bullit from a handgun, they collide and bounce off other molecules long before they can ‘fall’ to earth under gravity.
@davidmhoffer
‘A simple two step process followed by the consequent well known laws of thermodynamics’ is not what I wrote. The ‘consequent and well-known thermodynamic processes’ are part of step 2. The paragraph that followed the second step points out the problems that arise when we go beyond the first two steps, which is where all the problems arise. The two steps themselves are theoretically and empirically well-founded.
‘Your own explanation boggles the mind’. I was trying to avoid writing a 500 line post explaining in depth what it means when a molecule absorbs a photon so I tried to cut the corner by writing ‘well-known thermodynamic processes’.
Ira Glickstein PhD’s post is just so wrong on so many levels that it would take thousands of words to deconstruct it and we would be no better off. I’m not going to do this, nor am I going to write an alternative description of the ‘greenhouse effect’ in a comment that will disappear out of view about ten minutes after posting.