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. Robert Woods showed in 1909 that “Greenhouses” don’t work the way the “Greenhouse Effect” does! In point of fact, it is properly called the “Atmospheric Effect”, as there is that error in the comparison, as Greenhouses work because they are “convective boundaries”.
Alas, myths are so hard to destroy.
Max
@Ira Glickstein PhD
‘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.’
How do they ‘block and reflect’ this radiation? Do you mean ‘absorb’ – in which case, how do they ‘reflect’ it. Or do you mean that they absorb some percentage and reflect another percentage?
‘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.
Hmm. So in Bangkok at night you can hold your hand up and feel all the warmth coming from the clouds?
AJB says February 20, 2011 at 10:16 pm
Arrgh, thermo should read tropo. Late and tired!
Pull the other Sydney says:
February 20, 2011 at 11:13 pm
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 .
These are good questions to Ira as he has reduced everything to radiation and is trying to measure heat content (the scales going down and reading more) at one place by using temperature. The only place where this is a correct metric is ocean temperature (the total ocean temperature) as that would give a reasonable guide to Earth heat content. Atmospheric temperature is not a measure of atmospheric heat content.
Ira has (like almost every physicist) completely disregarded atmospheric enthalpy – so let’s give him a pass and assume that he really meant to indicate that it was ocean average temperature that the scale was measuring and that is equivalent to heat content.
However, that creates a problem in another way – as the blue balls will bounce off the ocean with an infinitesimally small effect ‘on the scale’ as while the orange balls can go deep into the ocean and warm it up – the blue ones cannot. So from the ‘ocean scale’s’ point of view they are effectively of zero mass. Note that the oceans cover 2/3rds of the planet so this is not a minor consideration.
The disregard of water goes further. As the temperatures increase so water vapor levels will increase (Henry’s law) and this will lead to convection carrying the water vapor up and pulling drier air in over the surface which picks up even more water vapor and so on. Each molecule of water in the water vapor has taken the latent heat of evaporation with it from the surface. Of course as every AGW proponent will tell you this increases the green house effect as lots and lots more blue balls will be trapped and split by the water vapor (although as we said this will have zero impact on the oceans). However, as the water vapor rises the lapse rate means that the volume of air cools and eventually the water vapor condenses into water droplets and then into ice latent heat is given off to the surrounding air at each of these phase changes, with two effects. One the convection upwards continues as the air is warmer AND the (latent) heat in the water has been carried past the main CO2 trapping and two the droplets start reflecting incoming radiation. Or to use Ira’s little analogy as the scales get pushed past a certain point a sunshade is created over the scales and some if not all the orange balls are bounced straight back out to space without affecting the scales. This is the Earth albedo increase that like convection Ira has ‘forgotten’ to add to the analogy.
So to the simple analogy we need to add that:
* the blue balls have ZERO effect on 2/3rds of the Earth’s surface.
* Most energy reaches the tropopause (the top of the convective atmosphere) by convection NOT as blue ball radiation and this is well above the main density of CO2 so as these blue balls are created above the CO2 most escape without being caught
* Clouds that form as water condenses into droplets and then freezes into crystals raise albedo that can prevent most of the orange balls reaching the surface.
One of the aspects not considered at all in this simple (simplistic?) analogy is the overall impact of the hydrologic cycle on the heat into and out of the planet.
– Initially as water vapor the feedback to heating is strongly positive as water vapor ‘traps’ (catches far more blue balls) than CO2.
– As water vapor rises and begins to condense into clouds the albedo starts to rise and the feedback of the system to more heating starts to become neutral
– Eventually if the clouds are dense enough and reflective enough the feedback can go negative due to albedo bouncing away almost all the orange balls. (This has been shown with ERBE measurements)
There is not ‘one’ simple feedback for the atmosphere the effect of water vapor and convection and albedo from clouds leads to a stabilizing feedback.
(Of course this is as simplistic as orange and blue balls – but it at least shows some understanding of the hydrologic cycle and its effect on the energy flows rather than just looking at the overblown effects of CO2 )
Thanks Ira for your answers.
Can we infer from your explanation that the atmosphere over the tropics has a more enhanced “greenhouse effect” than does the atmosphere over a desert ( due mainly to water vapour) and therefore if the models are correct and c02 plays a role in enhancing the greenhouse effect we should see a narrowing of the day/night temperature differential in desert atmospheres over time.
@John Brookes
‘RichardSmith, you are a bit harsh … attempts like Ira’s are good.’
Ira Glickstein PhD’s analogy will bring no one closer to an understanding of the greenhouse effect. It is just so wrong. On the contrary, it will just get people confused.
Instead of presenting the greenhouse effect directly, Ira Glickstein PhD has us all wondering about a barrage of balls of infinitely elastic energy bouncing off a table top placed on a set of kitchen scales. The kitchen scales give us a temperature reading of the surface. The balls then split into two, which is supposed to represent absorption… I just can’t go on…
I’m trying not to be ad hom, but this guy has some issues.
I’m only relieved that Flubber somehow stayed out of the analogy.
. A greenhouse works primarily by preventing absorbed heat from leaving the structure through convection, i.e. sensible heat transport.
Ira, I have to take issue with this explanation. A greenhouse works because when light comes through the glass of the structure, it is shifted to longer wavelengths that can no longer penetrate the glass.
This is not true with the atmosphere and greenhouse gases because the probability function of reflection in a greenhouse is 100% while the probability function of reflection due to GHG gasses, at the concentration in the atmosphere today, along with the fact that the absorption wavelengths are small, is a small value (ignoring other factors).
I am not the Richard Smith who has posted so far on this thread.
The diagram is false because the purple balls bouncing up meet the purple balls coming back down. So the descending purple balls never reach the ground (the scales in the diagram) because the force of the ascending balls is greater than that of the descending balls. (They have twice the mass in the diagram.) The descending balls simply slow down the upward progress of the ascending balls. So energy is conserved.
As an engineer familiar w/insulating effects, the “greenhouse” effect, at least qualitatively, is pretty straightforward.
For any object at a higher temp than the surroundings, anything that impedes the loss of heat to the surroundings (in the earth’s case, cold outer space) will cause the object to either rise in temp or cool more slowly. Whether this is thru a layer of solid/liquid that confines convection/conduction and/or absorbs outgoing radiation, or a layer of gas that absorbs some or all outgoing radiation, doesn’t matter. It will cause some insulating effect. How much and where are the questions.
One caveat above is that I’m assuming the object’s heat input, either self-generated or from, say the sun, is NOT impeded by the presence of this “insulation”. GHGs typically don’t interfere w/short-wave incoming radiation from the sun. Something like dust, clouds or SO2 droplets in the atmosphere that absorbs, reflects, or scatters incoming solar SW radiation is a different matter — that can cause cooling. Willis E’s “Steel Greenhouse” was for an internally-heated body, not for an externally heated one w/an atmosphere transparent to incoming SW radiation.
Ira
You have produced a simple analogy which illustrates the principles behind the ‘robust science’ as proferred by those who expound the AGW theory.
However, this is far removed from the real world (with convection, conduction, evaporation etc which are the overwhelming features of our atmosphere and which dwarf the effects of CO2). Just one and perhaps the most obvious point you are missing is that none of your graphics illustrates the position when the sun is switched off (ie., night).
During the night, there are no yellow balls; there is nothing to weigh down the scales (which now drop to a recording of less than 1) other than the little purple balls which gradually during the course of the night completely dissipate so that no extra warmth is locked in.
During the course of the seasons, and on every clear night whenever there is a temperature inversion, any heat that has been built up is shed. One can see how little heat trapping effect CO2 has when one considers night temperatures on a cold, dry and clear night, or for that matter night time dessert temperatures.
Unlike a green house (with solid glass ceiling and walls), the so called greenhouse gases do not provide an inpenetrable blanket. They are full of holes and thus the heat/energy escapes.
If CO2 really had the ‘magic’ properties you suggest, double glazing would be widely spaced and filled with an enriched CO2 atmosphere which would then heat the glass and make the glass panes act as if they were panel heaters. Double glazing would not simply act as an insulator to slow down heat loss from the room but could instead be used as the main source for heating a room.
I am one of those people whose brains work by visulisation. Don’t forget the wheel was invented without the use of maths and the initial idea of the bouncing bomb was too so thanks Ira for the analogy.
As for the question by Doc Martyn why isn’t co2 being used in greenhouses, it is.
What I have been trying to find out is if these greenhouses need more heating than normal geenhouses?
Sorry that sould have read less heating!
As a quick sidetrack, Einstein was wrong to state there no difference between acceleration due to gravity as compared to acceleration through space. The reason being is I can simply place a gravity meter at my toes and at my head. If the meters read different then my acceleration is due to a gravitational field. The reason being is that in the case of a gravitational field the strength of gravity CHANGES based on your distance from the source.
If my acceleration is due to motion, then both gravity meters will read the same since my body will not experience a change in a gravitation field. In other words, the assumption Einstein makes is incorrect.
I should also point out that in the case of a real greenhouse there is not some substance in the air that traps the heat in that closed house. It is the glass that prevents movement of the air that causes heat to be trapped. In other words, the glass prevents convection of heat and this effect is NOT due to some substance in the air that traps energy. So the greenhouse effect in terms making your car or greenhouse warm inside on a cold day is due to a VERY different physical process then how the Earth’s atmosphere traps energy.
So to be really clear there is actually no greenhouse effect in the atmosphere in the sense as to how greenhouses work. So while co2 and other substances can trap energy in the atmosphere one must keep in mind that process is complete different then how a greenhouse works.
This explains why some point out there is no such thing as a greenhouse effect in the atmosphere (they are correct). However those same people accept that gases in the atmosphere can trap energy.
So the Earth’s and atmosphere trapping of energy is not due to stopping of convection or a simple preventing movement of air like a real greenhouse does. Thus the term greenhouse effect to describe co2 in the air is a very poor choice of words.
Richard Smith,
“Publishing this kind of rubbish just exposes you to ridicule.”
Why do you have to be so nasty? While it is true that analogies can sometimes confuse, Ira was attempting to deal with a specific problem, namely the misunderstanding over ‘where did the extra truckloads of energy come from?’ That’s it really, and I think Ira did a wonderful job. And based on the comments so far, so do many others.
A fascinating discussion and the core physics is not really in question. The ‘greenhouse’ hypothesis has been around for the best part of a century but until the 1980’s was dismissed out of hand by most scientists in the field. The problem is how the differential absorption of radiation by the CO2 molecule plays out in the real climate. Leaving aside the anthropogenic/not anthropogenic argument what we should clearly observe is a dependable relationship between changes in CO2 and changes in global mean temperature. The critical word here is ‘change’.
This is a very simply empirical proposition. Taking annual % change in T as our response variable and annual % change in CO2 emissions as our explanatory variable the R2 should tell us the proportion of variability in the former that can be explained by the latter. The data is easily available through the NOAA and setting up the regression in this way eliminates most of the problems in handling the relationship between the two variables, (eg data recalibration, UHI effects, unit root problems etc) but more crucially it targets the empirical hypothesis we are interested in.
Following Ockham’s Razor, I started with a simple linear regression. Result? R2 insignificantly different from zero. Slope, such as there is, negative. Fascinated I repeated the experiment using various data lags – zero R2. I then tried various fancy transforms of the explanatory data, I used ocean as well as air temperatures, then in desperation tried the combined air/ocean temperatures. Conscious that the effect may be more significant at higher concentrations I time sliced the data just to make sure. Result: R2 = 0. Finally I did something very bad: I regressed nominal CO2 against nominal temperature. Result: R2 = 0.77. Totally meaningless: autocorrelation is a seducer of souls. I haven’t tried it but I suspect there is a good relationship between global mean temperature and the annual goals scored by Watford FC.
At this point I assumed someone else had done this almost trivial statistical experiment before. In the International Journal of Geosciences (Soares, P.C., (2010) Warming Power of CO2 and H2O: Correlations with Temperature Changes, International Journal of Geosciences, 2010, 1, 102-112.) I found the corroboration I needed. Now I know the IJG is regarded as a rubbish journal by the cognoscenti but hey-ho if the author has done what I have done then we are both missing something or there is a rather large problem with the whole debate about the greenhouse effect.
Result of all of this: having unquestionably supported the greenhouse gas hypothesis I became a 50:50 sceptic. Maybe it’s right, maybe it’s wrong. A bit of data, a spreadsheet and an hour working the problem and I now need a lot of convincing that the beautiful bouncing balls have any real meaning.
Ps: Watford’s goal scoring did increase dramatically during the 80’s and 90’s but then flattened off – maybe even declined since about 1998.
Could someone explain why water vapour does not do to itself what CAGWA’s assert that increasing CO2 will do to it? The theory is that heating from increased CO2 will warm the earth, sea and atmosphere and so produce more water vapour, the foremost greenhouse gas in total effect, which in turn warms the system further and releases both more vapour and CO2 from the seas. So why doesn’t summer, with its increase in water evaporation levels, lead to an irreversible thermal runaway? (And don’t say because it’s winter in the other hemisphere?)
The problem is that when CO2 absorbs a 15 um photon emitted by the surface, before that CO2 molecule can re-emit it (half downward as people like to think), it is immediately absorbed by another atmospheric molecule through collision.
The excited CO2 molecule will experience many thousands of collisions with other molecules before it can re-emit that photon.
The up and down re-emittance is only relevant for atmopsheric heights of 10 kms to 20 kms high where the emittance time becomes faster since it is colder and the density of the atmosphere reduces the collision rate. Emittance to space from this height then becomes a 50:50 proposition.
Very few 15 um photons re-emitted by CO2 will make it back to the ground except from those that are 3 metres high, not from the tropopause. Think of how many CO2 molecules a 15 um photon has to skip past to make it back to the ground from 10 kms high.
If CO2 is absorbing 15 um photons on the way up, they are also absorbing them on the way down.
I found these references of interest :
http://acmg.seas.harvard.edu/publications/jacobbook/bookchap7.pdf
http://www.geo.utexas.edu/courses/387H/Lectures/chap2.pdf
As to the atmosphere not getting sunlight at night, consider the average temperature of
the atmosphere to be 255 K, an underestimate, figure how many joules it takes to warm the atmosphere to 255 K, and figure how much additional joules the earth
gets during a day. It works out that the joules we get during a day amount to about
3% of the amount of joules in a 255 K atmosphere- the atmosphere loses only about
3% of its heat overnight.
Ira,
Your explanation to Pull the other Sydney is incorrect. When the tropics are cloud free, they still don’t radiate near as much heat as a desert. Clouds play a role, but it is minor. Also, your explanation violates two laws of thermodynamics. Electromagnetic radiation will not transfer information from a cold source to a hot source. In other words, if the earth is radiating heat toward he CO2, then the CO2 cannot radiate heat back toward the earth. It must radiate it to deep space, or at least an object that is cooler.
I suspect part of the reason some don’t believe in the greenhouse effect is the fact that people cannot SEE greenhouse gases. We can SEE clouds- greenhouse gases operate the same way as clouds, but somewhat less effectively.
I know this analogy has been used before, but they operate the exact same way as a coat in winter. Your body is at 37 C, you put on your coat at go out in 0 C weather. The coat is heated up by your body, then radiates the heat away in all directions, half to the outside air, and half back to you, making you less cold than if you were standing naked in 0 C weather. Not believing that gases can have a greenhouse effect is like believing that wearing a coat in winter is a wast of effort, time, and money because it will keep you from freezing.
Master of Obvious says:
February 20, 2011 at 8:22 pm
Masters,
Satellites have been measuring Outbound Longwave Radiation (OLR) from the Top Of the Atmosphere (TOA) for over thirty years. That OLR is a fairly good measure of the rate of energy lost to space. Radiation from the earth’s surface (absent any atmosphere) is proportional to it’s Skin Surface Temperature (SST) to the fourth power. Any atmospheric processes that slow down the rate OLR can be considered a resistance. Think how clouds and high humidity reduce the rate of cooling at night. Now is CO2 appreciably reducing OLR? My answer is NO. For a more detailed explanation, click on my name.
If water vapor has an amplifying effect as climate modelers claim, why is the daily mean temperature in a dry, desert area warmer (in spite of nighttime cooling) than a humid tropical area at the same latitude? For example, in Yuma, AZ the daily mean temperature for July is 94.1 degrees, while Montgomery, AL is 81.8 degrees.
What the modelers ignore is the cooling effect of clouds due to albedo, precipitation , and evaporation.
One other comment on CO2. Since it only intercepts IR radiation in two narow bands, most of the IR passes unhindered to space. It’s like a greenhouse with most of the glass missing.
@cal, concerning the atmospheric window
Looks like we are arguing whether minor increase in 1m2 wall insulation will do any effect indoors, when windows and door are wide open into winter night
I still do no know answers on these basic questions
– when CO2/water vapor will absorb IR, it will pass it as thermal energy to surrounding molecules, or re-radiate it, or depends on the altitude
– if CO2/H2O re-radiates the IR, the frequency is the same as absorbed, or it is changed? Because matter radiates only based in its temperature.. or CO2 at -50C radiates 20C warm IR backwards?
– when all molecules including N2 and O2 radiate IR according to their temperature, how can we recognize and quantify the radiation effect of the single anthropogenic CO2 molecule, which makes only one of 10,000 other molecules?
Brian says
Note to Don Shaw: clouds are not a gas, GH or otherwise. They are water droplets suspended by Brownian motion and updrafts.
Thanks, you are absolutely correct water droplets are not a gas. Possibly you can help me with several questions.
Are you also saying that there is no local concentration of water vapor associated with those water droplets that are in equilibrium and respond like a greenhouse gas?
We know that clouds locally have a huge effect of preventing the suns energy from heating the earth’s surface during the day and also preventing heat from escaping in the evening. Are you suggesting that the impact of a cloudy day/night has nothing to do with the “greenhouse” effect? If not, much of the discussion about the significant effect of CO2 seems to be greatly exaggerated.
Also I note that:
Ira says
“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.”
To Eric Anderson…
People are adding CO2 to greenhouses, but they do not notice any increases in temperature (not 1C or 3C or 4.5C or 8C).
See: http://academic.research.microsoft.com/Paper/5017614.aspx