Thread Rating:
  • 1 Vote(s) - 3 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Layman struggles with Science
#41
Derek, thanks for the reminder. I did need to reread that thread. Ferdinand's comment confirms ALL energy absorbed by CO2 is redistributed.
Quote:"So, the answer is really all the original photon energy is redistributed."

This means CO2 does NOT re-radiate any energy received from a higher termperature source, it will radiate at it's local environment temperature as a cooling function but I don't see how this can provide any "forcing" to the much warmer surface.

This will slightly simplify my question to: "How much heat energy is transfered to the 3 tons plus of air by the contained mass of 1,860.86 grams of CO2 that can only "see" 8% of the total upwelling radiation? I must assume there will be a steady rise in temperature over time, but what timescale/temperature riserate are we looking at?

Have you seen the latest Guest post by Willis Eschenbach over at WUWT?

The Steel Greenhouse

I see there is a comment by Monckton of Brenchley (15:30:32) :

In my struggles to understand the GHE I was fooling with "layers", hoping I could find an "Ah-Haaa!!" moment. My 1 meter layer of CO2 at 2,500 meters produced such big numbers that my confusion rate went logarithmic so I reduced my layer (shell ?) to 2 millimeters of CO2 at 5 meters.

Your comment answered my question about how much absorbed energy will go to heating the air. Answer: all of it! And how much is re-radiated. Answer: Non of it!

Progress, of sorts.
Environmentalism is based on lies and the lies reflect an agenda that regards humanity as the enemy of the Earth. - Alan Caruba
Reply
#42
From what I have read,CO2 emits at a lower wavelength than it had received.

I have also read about the real cause of a warmer atmosphere,than it should be.Atmosphere Pressure on temperature has been discussed here in the link below,worth reading.If true then CO2 barely warms ANYTHING at all.

http://omniclimate.wordpress.com/2008/03...e-warming/

Additional links for more background reading:

http://omniclimate.wordpress.com/tag/venus/
It is our attitude toward free thought and free expression that will determine our fate. There must be no limit on the range of temperate discussion, no limits on thought. No subject must be taboo. No censor must preside at our assemblies.

–William O. Douglas, U.S. Supreme Court Justice, 1952
Reply
#43
SST, I have not followed the links you have given yet,
but first impressions are - the virial theorum.
The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.

H. L. Mencken.  

The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
Reply
#44
More stuff to baffle whats left of my poor old brains. Reading WUWT today, I came across a comment about "thermal conductivity". The comparison between air at 0.024 (W/mK) and carbon dioxide at 0.0146 (W/mK) LINK caught my attention. I understand that thermal conductivity applies mainly to solids and fluids but this made me think that however much radiative energy CO2 absorbs, it will not be very efficient passing this heat energy to the surrounding air before it (the CO2) reradiates its excess energy.

So it would seem CO2 is not very good at warming the atmosphere.

Further to my posts about the number 2,500 (two thousand five hundred), I am going to try this on a neighbour who is a bit of a warmist; show him an empty 2 litre plastic bottle and get him to confirm it is full of air. Then ask him how much CO2 is in the bottle, I'll be surprised if he can tell me, but that would be excellent as I will then ask him to think about 2,500 bottles and ask if all the CO2 were collected into just a few of the bottles, how many bottles of pure CO2 would he have?

The answer of course is 1 (one), i.e. 0.04% of the bottles. I am hoping this idea can convey the concept of a trace gas. If any of you have children at school see if you can get them to ask this question of the science or maths teacher.
Environmentalism is based on lies and the lies reflect an agenda that regards humanity as the enemy of the Earth. - Alan Caruba
Reply
#45
Quote:So it would seem CO2 is not very good at warming the atmosphere.

How could it when so little of the atmosphere can absorb IR.Only "greenhouse" gases can do that and that is mostly water vapor,CO2 and Methane.

Cool
It is our attitude toward free thought and free expression that will determine our fate. There must be no limit on the range of temperate discussion, no limits on thought. No subject must be taboo. No censor must preside at our assemblies.

–William O. Douglas, U.S. Supreme Court Justice, 1952
Reply
#46
(12-24-2009, 01:50 PM)Sunsettommy Wrote:
Quote:So it would seem CO2 is not very good at warming the atmosphere.

How could it when so little of the atmosphere can absorb IR.Only "greenhouse" gases can do that and that is mostly water vapor,CO2 and Methane.

Cool
Hmmm... but this is the main pillar of the AGW claim.

I know, and you know, the problem is how to convince the indoctrinated who have been fed AGW propaganda since their school days. My daughter is 27 with a PhD in microbiology and she can quote chapter and verse from her school before going to uni of all the terrible things that will happen to the planet if we didn't change our ways and reduce our consumption of everything. She understands now that humanity has many problems, AGW is a non-problem being used as a lever to gain political control. This is the real problem.

But for those of you interested in the science I think this is a useful site:

http://www.uigi.com/physical_prop_m.html

Be aware that warmists will claim this site is funded by big oil, but I say so what? Science is either true or false.
Environmentalism is based on lies and the lies reflect an agenda that regards humanity as the enemy of the Earth. - Alan Caruba
Reply
#47
Harpospoke can you add Richards latest link to your board?

Physical Properties of Industrial Gases and Common Industrial Chemicals
It is our attitude toward free thought and free expression that will determine our fate. There must be no limit on the range of temperate discussion, no limits on thought. No subject must be taboo. No censor must preside at our assemblies.

–William O. Douglas, U.S. Supreme Court Justice, 1952
Reply
#48
Quote:Hmmm... but this is the main pillar of the AGW claim.

Now you can understand why certain people are amazed at the stupid AGW claims.

Big Grin
It is our attitude toward free thought and free expression that will determine our fate. There must be no limit on the range of temperate discussion, no limits on thought. No subject must be taboo. No censor must preside at our assemblies.

–William O. Douglas, U.S. Supreme Court Justice, 1952
Reply
#49
I have been searching for some time, without success, for a defining value of the optical depth of the atmosphere where ALL radiation at the specific bands for CO2 is totally absorbed.

On reading Pat Tyson's essay THE DYNAMIC ATMOSPHERE...

Quote:The Particulate Nature of the Atmosphere: The gases of the atmosphere comprise some 99.9% of its mass. However, at sea level, these gaseous molecules effectively take up less than 0.1% (one-tenth of one percent—that is, one part per thousand) of any volume of atmospheric air. At higher elevations they take up even less of the available space.

The atmosphere is not in any way a continuous fluid. It is a collection
of very small discrete particles—molecules. The space between the
molecules of the air is just as much an empty vacuum as anything you will find in interstellar space.

Indeed, even the “volume” of an individual molecule itself is
comprised almost overwhelmingly of empty space, with the mass of the
atomic nuclei and the surrounding electron “clouds” taking up a very small percentage of that molecule’s effective “volume”.

In essence, most of what we see and feel as solid matter is—in
reality—empty space in which small particles move about at high speeds in unpredictable and constantly changing directions. It is really those random movements at high speeds that make “solid” matter to appear to be actually “solid”.

...I had an idea. We are told the atmospheric level of CO2 is 395ppmv and it is "well mixed". So if I take 400ppmv this works out at 1 part in 2,500. Thus a one meter square air column 2,500 meters tall will contain the equivalent of 1 cubic meter of CO2. From Tyson's quote above that CO2 will equate to a solid layer of CO2 one millimeter thick. That MUST stop some radiation!!!

I would venture that half a millimeter equivalent of solid CO2 would stop
any radiation and that means 1,250 meters of air, that level is just one and a quarter kilometers up.

So I feel fairly confident in assuming all radiation in the bands 2.7, 4.3
and 15 micrometers (µm) outgoing longwave radiation from the earth's surface will be completely absorbed in the atmosphere within the first kilometer and a quarter. Frankly, I think the real level may be lower.

The actual height of the absorption layer is not that important, what is
important is that there are MANY layers capable of absorbing all the energy that will interact with CO2 in the atmosphere.

Now consider what happens to the absorbed radiation. The CO2 molecules have been raised to a higher level of excitation resulting in faster movement and more collisions with surrounding air molecules. Some of this energy is transfered to the air raising the temperature and the remainder is reradiated such that half continues up and half returns to the earth's surface. The question is how much heat is conducted into the air? I have read that the thermal conductivity of CO2 is worse than dry air which is itself considered to be a good insulator. It is beginning to look like CO2 not only does not, but cannot, heat the air to any great extent if at all.

But what about the surface. We see from above that nearly half the specific outgoing radiation is returned. I read in James Peden's page that total energy from a blackbody radiator contained in the bands mentioned above amounts to some 8%. Since half of that returns we can say 96% of radiated energy passes through the first kilometer of air assuming no low level cloud or fog etc. which is another whole different ball park.

Right, we have a "forcing" of 4%. Assuming the surface is radiating at
15W/m^2 then we get 0.6W/m^2 of "forcing".

What about the rest of the atmosphere? Okay, consider the next kilometer up. This level sees 4% and reradiates 2% up and 2% down. The bottom layer sees and absorbs that 2% and passes 1% down and 1% back up. (emission/absorption works in both directions).

Thus the second layer has raised our surface "forcing" to 5% or 0.75W/m^2. The third layer, up to three kilometers sees 2%, passes 1% and returns 1% which is reduced to 1/2% at second layer and 1/4% at the surface and so on through the layers. If you continue the argument you will find that the total surface "forcing" of CO2 in the atmosphere cannot exceed 6% or 0.9W/m^2. This figure will rise and fall with the surface radiation level such that at 30W/m^2 we will get a max "forcing" of 1.8W/m^2.

By this argument CO2 will be responsible for 6% of surface forcing whatever the surface temperature is and will NOT change for increasing or decreasing CO2 levels.

So if CO2 levels are reduced to 200ppmv temperatures will not change but all life on earth will die. Plants do not grow at 200ppmv or lower.

Now look at the upper atmosphere, from say 6 kilometers up. Here the CO2 is not seeing any radiation at all at 2.7, 4.3 and 15 micrometers (µm), but being a much better radiator than oxygen or nitrogen it is increasing the rate of cooling as CO2 increases.

To summarise, the "greenhouse" effect of CO2 is real but constant. Rising levels of CO2 does not raise surface level temperatures but does increase upper troposphere cooling.
Environmentalism is based on lies and the lies reflect an agenda that regards humanity as the enemy of the Earth. - Alan Caruba
Reply
#50
I think I was a bit generous with my 6%. First layer reflects 4%, secondlayer adds 1%, third layer adds 1/4%, fourth layer adds 1/16% and next adds 1/64% and so on. Basically adds up to 5.336% back radiation. Remember this does not heat up the surface, it reduces the rate of cooling hence the term "forcing" (I think).

I also think the level of heat radiated must be somehow related to the fourth power of the temperature but I don't know how to do that yet. This implies the "reradiated" energy coming from a colder source (think lapse rate) will be less than my assumptions. Either way it remains a constant for CO2 in the atmosphere.
Environmentalism is based on lies and the lies reflect an agenda that regards humanity as the enemy of the Earth. - Alan Caruba
Reply
#51
Quote:Remember this does not heat up the surface, it reduces the rate of cooling hence the term "forcing" (I think).

I believe that is the understanding,but it is so little that there is no reason to have the panic over it.

I never have been able to see how a "returning" to the surface IR emission from CO2 molecules can increase the surface temps because it is actually cooler than the surface.

I got an answer recently from a scientist Jack Barrett,that as usual fails to answer my question of how much of the emission from the CO2 molecule is still in the same wavelength that it had absorbed in.I had stated at the closed climate forum that it had to lose some of it for the emission to occur.Thereby the now lower IR band wavelength can no longer be re absorbed again,being effectively outside of the known main CO2 IR absorption range,but Water Vapor still could absorb it.

I ask because if it always emitted at the same exact wavelength it had absorbed,there would be an endless re absorption of IR going on to the point of saturation and a far warmer atmosphere.Then any addition inflow of CO2 into the atmosphere would promote a true endless warming trend.

In Chemistry I was taught that a "daughter" photon had to occur before a molecule can get out of its ionized state and emit the packet of kinetic energy.Thus a small loss of energy allowed the rest of it to leave the molecule.

Hopefully Richard Courtney will come back and help us on this.
It is our attitude toward free thought and free expression that will determine our fate. There must be no limit on the range of temperate discussion, no limits on thought. No subject must be taboo. No censor must preside at our assemblies.

–William O. Douglas, U.S. Supreme Court Justice, 1952
Reply
#52
Friends:

I have just returned home and have yet to unpack so this is a brief answer. Please say if it is not adequate and I will try to get back.

Ignoring clouds, the air is transparent to short wave radiation from the Sun so that solar radiation travels to the Earth's surface where it is absorbed. This absorbed radiation is energy so it heats the surface. And the surface has to lose the heat it gains from the absorbtion or it would get hotter and hotter with time.

The surface loses most heat by evapouration (as we do when we sweat), by conduction with air (trivially), and by radiation in the form of long wave, infra red (IR) radiation. In this context the IR radiation is of concern.

The air is not transparent to the IR from the Earth's surface because the air contains molecules of gases (known as greenhouse gases, GHGs) that can absorb the IR.

The main greenhouse gas is water (H2O) not carbon dioxide (CO2). Water is by far the major greenhouse gas. Estimates vary, but water is responsible for at least 70% of the radiative greenhouse effect. Cold air contains less water than warm air (which is why dew forms just before dawn), and the air in near polar-regions is very cold so it contains almost no water. Hence, any effects of changes to carbon dioxide in the air will not be masked by effects of water in near-polar regions, so effects of changes to carbon dioxide in the air will be most clear in the near polar-regions. For this reason it is often asserted that the rapid warming now occurring in the Arctic region is evidence for AGW.

Radiation consists of discrete particles of energy known as photons. A GHG molecule can absorb an IR photon that has a certain wavelength. Carbon dioxide can absorb at three IR wavelengths and the most important in this context is close to 15 microns. (in fact, absorbtion of photons with near to ideal wavelength can also happen but that detail need not concern us here).

The ~15 micron photons emitted from the Earth's surface are almost all absorbed by molecules of water and carbon dioxide in the lowest 100m of the air.

A GHG molecule that absorbs a photon is said to be 'excited' (most things get excited when their bottoms are hit Rolleyes ). The excitation can be rotational or vibrational, and it raises the molecule to a higher energy state (it has absorbed energy).

Some excited molecules will lose their gained energy by colliding with non-GHG molecules (e.g. nitrogen or oxygen molecules) and their loss of energy gives heat to the non-GHG molecules with resulting warming of the air. Many more excited molecules will lose their gained energy by emitting a photon of IR. They are said to 'de-excite' when they lose the energy of their excitation.

The photons emitted by de-excitation of GHG molecules are emitted in random directions. Therefore, half of these photons are emitted in upwards directions and half are emitted in downwards directions.

Many of the photons from de-excitation that move downwards will not collide with another GHG molecule. So, they will reach the Earth's surface to heat the surface some more. This additional heating is the radiative greenhouse effect (GHE).

It is sometimes claimed that this GHE violates the Second Law of Thermodynamics, but it does not. That Law says heat travels from 'hotter' to 'colder'. It does not say that each of the thermal transfer mechanisms must be from 'hotter' to 'colder'. And the surface loses all the heat that it gains because the surface loses most heat by evapouration.

When considering a thermal transfer all the thermal transfer mechanisms (i.e. radiation, conduction, convection and latent heat) need to be considered.

If this is hard to understand then think of an electrical radiant heating element shining on a bowl of water. After some time the bowl will achieve a constant temperature (and be losing water by evapouration) but that does not mean it is radiating as much heat as is radiated at it by the electical heating element.

I hope this is clear.

Happy New Year

Richard[/u][/i]

The transfer of heat to the
Friends:

In retrospect, I think I should have been more clear when I wrote:

"Many of the photons from de-excitation that move downwards will not collide with another GHG molecule. So, they will reach the Earth's surface to heat the surface some more. This additional heating is the radiative greenhouse effect (GHE)."

It would have been better if I had said;

"Many of the photons from de-excitation that move downwards will not collide with another GHG molecule. So, they will reach the Earth's surface and will be absorbed by the surface. This additional absorbtion will add heat the surface. And this additional heating is the radiative greenhouse effect (GHE)."

Sorry for the lack of clarity.

Richard
Reply
#53
Friends:

OK. I have still not unpacked but have had time to reconsider (it is now nearing one o'clock in the morning), and I think my above answer missed the point being asked. It seems the relevant bit probably was;

"I ask because if it always emitted at the same exact wavelength it had absorbed,there would be an endless re absorption of IR going on to the point of saturation and a far warmer atmosphere.Then any addition inflow of CO2 into the atmosphere would promote a true endless warming trend."

If so, then I what I wrote was irrelevant.

The pertinent issue is time. The GHG molecule stays excited for a period of time before it de-excites. And excitation can only occur between adjacent energy levels. Hence, an excited molecule has limited ability to absorb another photon.

So, consider the case when a volume of the air contains a number of GHG molecules, say 100 molecules, that can absorb IR photons of 15 microns wavelength. If 50 of them are excited then they do not absorb 15 micron photons, so any such photons that hit them cannot be absorbed.

So, only about 50 of the 100 molecules can absorb 15 micron photons that impinge on them. Increase the flow of photons through the volume of air and more than 50 of the molecules will be excited at any moment. Hence, the proportion of absorbed photons decreases as the flow of photons increases.

For the same reaon, the proportion of absorbed photons increases as the number of GHG molecules in the volume increases. This effect of increasing GHG concentration in the volume is approximately linear until all the photons are absorbed and the system is then said to be saturated.

Almost all the 15 micron photons from the Earth's surface are absorbed in the lowest 100 m of the Earth's air. The 15 micron wave band is saturated.

But the band of absorbed wavelengths can broaden as it becomes saturated. So, there is a probability that photons with a wavelength near to 15 microns can be absorbed.

This band broadening is not linear. As the band broadens it becomes progressively more difficult for the band to broaden. And this is why the effect of increasing atmospheric carbon dioxide concentration is logarithmic (not linear).

I hope I have now answered the right question.

Richard
Reply
#54
Thank you Richard for your input. This is the sort of detail we are looking for. Hope you've had some sleep before you read this.

I can calculate the mass of CO2 molecules at 400ppmv (easy number) for any pressure/density level (Avogadro number tables) but cannot calculate how much heat is transfered to the air over any time scale. Just to get a handle on this I can assume an average night/day temperature cycle but cannot calculate surface radiation level in watts per square meter for a known temperature using temperature to the fourth power. I had a formulae for this but lost it in a clean up. Undecided

I realise I am looking at unreal ideal conditions but this exercise is to try and get some understanding of just how effective is CO2 at warming the air. You will note from my previous posts I believe CO2 CANNOT warm the surface. Also I attempted to derive from simple principles what you term a "saturation level" (see post #49) and plumped for 1000 meters. Your suggestion that it is about 100 meters does not effect my argument as to what I think is happening to the "backradiation". I know my conclusion is wrong since it flies in the face of current predictions/projections.

Trying to find explanations of the physics of this problem have eluded me so far. Any links to tutorials based at this level would be greatly appreciated.

All explanations I have found so far start with figures derived from satelite TOA readings or derived from "energy budgets" which have no explanations for the basic figures or they quote "forcings" from the IPCC and so on. I don't think the explanations derived from plastic bottles, seltzer tablets, thermometers and heat lamps have any validity.

Once I have a working idea on how surface radiation interacts with CO2 in the atmosphere I feel I would be able to progress towards dealing with different levels of water vapour, this will of course mean temperature/pressure must remain above the dew point, i.e. "dry" air. Then one day I hope I can look at the air/water interface with some understanding of just how much IR is delivered from the atmosphere.
Environmentalism is based on lies and the lies reflect an agenda that regards humanity as the enemy of the Earth. - Alan Caruba
Reply
#55
Richard111:

I apologise that my attempt failed to answer your real question, but if I had understood it then I would not have tried.

You say:
"I can calculate the mass of CO2 molecules at 400ppmv (easy number) for any pressure/density level (Avogadro number tables) but cannot calculate how much heat is transfered to the air over any time scale."

Wow! That is several PhD research projects! Fortunately the work has been done.

The best summation of the work is in the form of the commercially available Modtran software. Information about it and how to purchase it is at
http://www.kirtland.af.mil/library/facts...sp?id=7915

The software is not cheap.

A good example of its use is at
http://www.atnf.csiro.au/pasa/17_3/hidas...node2.html

Alternatively, you could try to copy and/or find fault with the Khiel-Trenbert method of determining the Earth's energy budget. It can be found at
http://www.cgd.ucar.edu/cas/abstracts/fi...997_1.html

Sorry, but - other than these probably unhelpful suggestions - what you are asking is so large that I do not think I can help by making blog postings.

I hope my postings above demonstrate that I am willing to try to help, but what you are asking is too much for me to be able to do it here. And I am sorry about this.

Happy New Year

Richard
Reply
#56
Richard, a Happy New Year to you sir. My goodness, please don't feel you need to aplogise for failing to answer an improbable or impossible question from a layman. Fair comment needs no apology besides I have been directed to MODTRAN several times already. Rolleyes

Many thanks for the links, especialy the one to the Electronic Publications of the Astronomical Society of Australia. Lots of interesting reading for me. MODTRAN is very much overkill for my level of study of climate phenomena.

Quote:Data from meteorological balloon launches from the South Pole were used to define the pressure, temperature and relative humidity profiles of our models (see CMDL/NOAA). The profiles for other atmospheric constituents (O3, CH4, N2O, CO, CO2, O2, NO, SO2, NO2, NH3, HNO3) were set to those from MODTRAN's standard ``subarctic winter'' model, which was closest to the conditions at the South Pole. However, these have a negligible effect on the sky emission in the infrared windows discussed here (MODTRAN allows the contributions of individual species to the total emission to be examined).

CO2 is just one of many constituents of the atmosphere catered for by MODTRAN which is a computerised number cruncher, a model. Before MODTRAN became a viable tool that has now become an essential adjunct to any climate reseach someone must have sat down with pencil, paper, log tables and possibly a slide rule to calculate the effect on the environment of each those chemicals and possibly many more. As you say above: "The work has been done." This is what I would love to read about. How the numbers for CO2 were derived before they were put into MODTRAN.

As for heat budgets, there are so many that I am concentrating on Pat Tyson's essay WATER AND THE EARTH’S HEAT BUDGETS in the hope that I will acquire some understanding of the subject.
Environmentalism is based on lies and the lies reflect an agenda that regards humanity as the enemy of the Earth. - Alan Caruba
Reply
#57
In my attempts to study the effects of CO2 on the atmosphere I am finding that it does almost nothing at all. This has to be wrong. Would some kind reader point out my error(s) please.

My starting point is the amount of CO2 in our atmosphere. The current level is some 390ppmv but I will use 400ppmv to help the numbers.

If we divide 1,000,000 by 400 we get 2,500, that means one out of every 2,500 molecules in the atmosphere will be a CO2 molecule.

We can also state that for every 2,500 cubic meters of air there will be the equivalent of 1 cubic meter of CO2. This is handy because we can look up Avogadro's number and find the mass of that CO2. It turns out that the mass will be a fraction under 2 kilograms. I will use 2kg.

I've learnt that if a volume of gas, any gas, is compressed to the solid state it will occupy just 0.1% of its original volume, thus our 1 cubic meter of CO2 molecules might be regarded as a 1 square meter, 1 millimeter thick, sheet of solid CO2. Now THAT would stop a lot of light! As luck would have it, it's just a gas.

In attempting to find the smallest mass value of CO2 that will still efficiently do its absorbing business I will reduce the CO2 by 90%. This leaves me with a 1 square meter sheet, 0.1 millimeters thick. Not much you think but that is still some 50,000 CO2 molecules deep and the mass is now 200 grams. The volume of air is also reduced 90% to 250 cubic meters to maintain the 400ppmv level for the CO2.

250 cubic meters of air at standard temperature and pressure will mass at 300,000 grams (300kg) and contain just 200 grams of CO2. That gives us a mass ratio of 1 : 1,500.

Here are the figures for Specific Heat in kJ/kg per degree C for the main constituents of the atmosphere

Oxygen ....... 0.9191
Nitrogen ..... 1.04
Argon ........ 0.523
Carbon Dioxide 0.85

Oxygen and Nitrogen together can be considered to have a specific heat value of 1 kilojoule per kilogram per degree C. So, for 99% of our air mass, 297 kilograms, it should not be too much of a problem to work out how much energy will raise the temperature by 1 degree, or more realistically, lets just try for a rise of 1 hundreth of a degree, after all, just 200 grams of CO2 is available to provide the heat. The question is: How much heat, for how long, to raise the temperature of 273 kg of air by 0.01C ?

Let us arrange those 250 cubic meters of air into a column and assume the surface it is standing on is radiating at 400 w/m^2. 92% of that energy will pass straight up the column with no effect. The remaining 8%, 32 w/m^2, the energy in the IR bands 2.7, 3.4 and 15 micrometers (µm), will be absorbed as the photons rattle their way up past 50,000 layers of CO2 molecules spread up that 250 meter column of air.

CO2 is just as good at radiating as it is at absorbing so it will quickly reradiate any excess energy, half will carry on up the column, and half will return to the surface. How much of any absorbed energy goes into heating up the surounding air I am unable to work out. So to continue this discussion I will assume minimal heat is passed to the surrounding air molecules.

I am ignoring the fact that the CO2 in the air is cooler than the surface, most of it is very much cooler. This will also have some impact on the back radiation for which, again, I am unable to find any information.

Note that 100% of that 400w/m^2 is leaving the surface and 4%, some 16w/m^2 is being returned.

THIS IS NOT ADDING TO THE ENERGY ON THE SURFACE.

The most you can say is that the radiating efficiency of the surface has been reduced to 96%.

A REDUCTION IN THE RATE OF COOLING IS NOT AN INCREASE IN HEAT.

So far we have dealt with a single 250 meter column of air. Stack another 250 meters on top and back radiation at the surface increases by 1%. Stack a third 250 meter layer and back radiation increases by a further 0.25%. Another and add 0.125% and so on. Each new layer will add 200 grams of CO2 to the system and back radiation at the surface decreases by a factor of four. As you keep stacking up layers you will find the back radiation tends towards 5.333% of the total radiation from the surface and cannot exceed that percentage. I will discuss line broadening shortly.

At 5 layers, 1,250 meters, the CO2 available will mass 1kg. We know it will require 850 joules to raise the temperature of the 1kg of CO2 by 1 degree C. But the CO2 is only absorbing 32 joules per second (32 w/m^2) so will need 26.6 seconds to achieve a 1 degree rise in temperature. Will the CO2 hang on to the absorbed radiation for such a time period? I think not. How about the time needed to achieve a rise of 0.01 degrees C, 266 milliseconds? Again far too long before the CO2 has reradiated most of its absorbed energy.


So that 1kg of CO2, which can hardly heat up itself, is expected to provide heat to 1,500kg of normal air.

Back radiation from CO2 in the low level atmosphere reduces radiation efficiency from the surface to a maximum of 94.666% and that figure will not change however much CO2 is injected into the air. If energy, in the form of heat, is passed into the surrounding air from the CO2 the the level of back radiation will drop. I have been unable to find any information that might clarify this point.

Move our column of air over water and things become very different. Although we will get the same backradiation level of 5.333% this does have some impact on the water. Water is effectively opaque to IR but happily absorbs all it can get even if it doesn't penetrate more than a few tens of microns. The air/water interface thus becomes more active improving the chances of water molecules escaping into the air thereby helping to cool the water surface by evaporation. When you consider that 70% of the planet's surface is water, this is an effective cooling agent. Again, this back radiation is a constant, the level of which will track the water surface temperature which doesn't change anything like as much as the land surface temperatures.

Line broadening. What is it? It is a function of temperature, the energy level of the molecule. The higher the energy level the more active are the atoms and electrons in the molecule contributing to increase in bending, stretching and rotating which result in the molecule being able to absorb and emitt some radiation each side of its observed spectral band. Think tuned circuit in electronics, warmer is wide band, cooler is narrow band. In a gas, free molecules will be moving quite rapidly, something in the order of 400 meters per second. Compared to the speed of light this is not much but it is enough. If a slightly lower band photon meets the molecule traveling towards it, the combined velocities result in the molecule absorbing that photon. If a higher band photon overtakes the molecule again the photon could be "in band" and absorbed. Higher temperature results in faster speed allowing more absorption. The energy level in the newly absorbed "side bands" is lower than the central peak. This phenomenon is very useful in spectral analysis but as yet I have not discovered how much difference the temperature makes to the total percentage absorbed and emitted with respect to a constant heat source. This does not change the above argument. I have used the figure of 8% energy utilised, but it could become 10%, but I do not know how much temperature change in the whole body of air, not just the CO2, is required to ensure this increase in energy utilisation. There are many regions in deserts where surface air temperatures rise to +40C and above and at the south pole the temperature drops to -60C and more. There is the same amount of CO2 in those locations so why is there no information on line broading and the effect on temperature? Because there is little to no effect recordable. I suspect line broadening requires temperatures in several hundreds of degrees but that happens on other planets. I simply cannot see how a global temperature rise of even 6C could cause a positive feedback when we already have changes in excess of 100C and no runaway global warming. After all, a positive feedback must start from a point source, it cannot just happen world wide "just like that".

To summarise, any "greenhouse effect" due to CO2 is minimal. CO2 does not and cannot trap energy in the form of heat. Any heat into the atmosphere is removed upwards at the normal dry adiabatic lapse rate. Note that this is also effectively a constant. Also note that CO2 is well mixed throughout the atmosphere and provides very effective cooling at and above 300mb.

The most important "greenhouse gas", water vapour, H20, behaves in a similar fashion near the surface but is not evenly distributed throughout the atmosphere. It can vary hugely through the vertical air column and horizontaly. H2O also exists in solid and liquid form in the atmosphere. These forms have close to black body reactions to longwave IR radiation plus considerable response to short wave visible light radiation. The physical presence of water or ice in the air required huge quantities of energy to exist and will release that energy whilst changing states.

CO2 does not and cannot effect any changes in the level of H2O in the atmosphere because it is already doing the most it can. The only feedback mechanism I can see is a slight increase of the rate of evaporation but that has remained the same since the CO2 levels were at or below 100ppmv and will remain the same if CO2 levels rise.

Any increase in CO2 is beneficial to all plant life and the animals (including humans) that feed on plants.

Non of the above is rocket science, just common sense interpretation of information available on the internet.

"Don't believe a word I have said, check it out for yourself."
Environmentalism is based on lies and the lies reflect an agenda that regards humanity as the enemy of the Earth. - Alan Caruba
Reply
#58
Richard111, please excuse this input, as I have not had time to fully digest what you have written,
(I have to fit heated grips to my motorcycle, so I'll be back later
- these supposedly warmer and wetter winters (according to UK Met office, are really freezing my fingers off....)
but in the meantime may I "throw in".

Here are the figures for Specific Heat in kJ/kg per degree C for the main constituents of the atmosphere

Oxygen ....... 0.9191
Nitrogen ..... 1.04
Argon ........ 0.523
Carbon Dioxide 0.85

If CO2 has a lower heat capacity than O2 and N2, will it not "react" first,
so at all times cooling the rest of the atmosphere it is in. ?

I am assuming that O2 and N2 mixed in the atmosphere will have the simple arithmetic heat capacity of
80% 1.04 + 20% 0.9191.
(roughly worked out as 1.015)
Is this correct. ?
The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.

H. L. Mencken.  

The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
Reply
#59
Derek, I had the same thought and gave them the combined value of 1 in my post. I don't know the answer but have assumed that is not critical. What I am trying to work towards is how CO2 can put any measurable heat into the atmosphere, while it also, as you mention, takes heat out of the atmosphere. Those are all my figures derived whilst contemplating my navel so to speak.
My last bike was a Honda Deauville, shaft drive 650 twin. (sigh)
Environmentalism is based on lies and the lies reflect an agenda that regards humanity as the enemy of the Earth. - Alan Caruba
Reply
#60
Happily I can report after a test ride of my TDM - toasty fingers.. Wink
AND the dynojet kit really has cleaned up the carburation - the gearbox is easier to use (revs fall back quicker so making changes sweeter).
It does seem to rev better / cleaner / faster - but I'd better not say that had I..

Anyways back to your post Richard111, I'm very interested in your point that CO2 very effectively cools the atmosphere below 300mb.
Could you expand on this please.

Excellant point Richard111.
" I simply cannot see how a global temperature rise of even 6C could cause
a positive feedback when we already have changes in excess of 100C and no runaway global warming.
After all, a positive feedback must start from a point source, it cannot just happen world wide "just like that".
"

I genuinely am now wondering if the lower specific heat capaciy is the key to demonstrating CO2 does not warm the climate.
When this is combined with CO2's ability to react radiatively, does it mean whether warming or cooling CO2 is always redistributing heat first.
The net effect of CO2 therefore being to slow warming and speed up cooling within the atmosphere.
This is exactly what the experiment with the plastic bottles shows, so maybe it is a basis to improve from.

I think your point re CO2 and back radiation may increase oceanic evapouration is possibly a very good one,
it is another example of an experiment that is needed, with results that could have large consequences.
Although I do wonder about the cooler thing can not warm a warmer thing problem.
Maybe there is a more complex set of circumstances in oceanic environments,
with shallow equatorial seas and deeper more "latitudinal" oceans being very, very different,
then there are cold and warm upwellings, etc, etc.
There could even be times when back radiation from a very warm / shallow sea, or nearby land,
could actually be warmer than the deeper cooler ocean in the near locality,
remembering back radiation occurs over a wide angle (just under 180 degrees).
But this would presumably be an exception rather than the "rule".


" So that 1kg of CO2, which can hardly heat up itself, is expected to provide heat to 1,500kg of normal air. "
Would it warm up, or would it simply redistribute the heat radiatively. ?
Effectively taking the heat out of the atmosphere, because of it's lower heat capacity and physical property of reacting radiatively.
The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.

H. L. Mencken.  

The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
Reply




Users browsing this thread: 1 Guest(s)