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The Myth of Backradiation
#1
Claes Johnson on Mathematics and Science

June 25,2010

EXCERPT:

AGW alarmism is based on an idea of "back radiation" or "re-radiation" from an atmosphere with greenhouse gases, but the physics of this phenomenon remains unclear.

To test if "back radiation" is a real phenomenon, we suggest the following experiment: On a night with moon-light so feeble that you can cannot read a newspaper, place yourself in front of a mirror letting the moonlight reflect from the newspaper to the mirror and back again, and check if you can now read. You will probably find that the paper is still unreadable, as if "back radiation" does not give more light.

LINK
======================================================
In the comment section.There is a man named Roger,who is providing a terrible defense of the backradiation accumulation effect.

He is obviously one of those AGW believers we have come to expect.He is being taken apart so easily it is sad that he seems unaware of it.
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
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#2
Well well,

I have been reading both sides of the argument for a while and come away wondering why so many skeptics believe in the back-radiation effect?

Why do the majority of the skeptics feel the need to be hostile over the possibility that maybe back-radiation does NOT warm up a surface that is hotter than the back-radiation itself is?

It seems that Back-radiation claims as according to the Trenberth and Teuscher model comes close to being a perpetual source of nearly free additional energy source?

Maybe Richard Courtney can tell us why we should accept it?

Maybe Alan Siddons can tell us why we should NOT accept it?

Here is a chart to excite anybody!

[Image: divine.gif]

So is it ISOTROPIC or one directional back to the surface?
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
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#3
So is it ISOTROPIC or one directional back to the surface? Rolleyes

I tried to work it out for myself using my logic Tongue and came to the conclusion any back radiation will be a constant in terms of the level of surface radiation and will not change at all if "greenhouse" gases change. Of course there is massive hourly/daily changes of low level "greenhouse" gases, think water vapour, aka humidity, and temps just behave normally.

Then the absorption of LW IR in the upper atmosphere. By my reasoning none of this reaches the surface if it is part of the gas spectrum. What LW IR that does come through is through the "window". This window works both ways unless blocked by clouds. But then, what do I know.
Environmentalism is based on lies and the lies reflect an agenda that regards humanity as the enemy of the Earth. - Alan Caruba
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#4
I suggest we use this thread to produce a list of agreed errors or inconsistencies in the diagram, as suggested by Derek elsewhere. Perhaps I could use this post to create and add to the list?

1. The 324 back-radiation is shown as all absorbed by the surface. No albedo effect is indicated. Using the same albedo implied by the "30 reflected by surface" on the left gives 59 out of the 324 reflected.

The albedo (for LW IR) won't be identical to that for the mixed solar irradiance shown at left, but I can make an attempt at an educated guess. For example 2/3 of the effect will be due to reflection by water, part of the rest by vegetation, and the remainder by rock/soil/sand with a small element of ice/snow. I found tables of albedo for both visible and IR a while ago. Unfortunately (unlike normal practice) I didn't bookmark it, but should be able to find them again. In any case, it won't be strikingly different, but has to be taken into account.

There's a "165 emitted by atmosphere" at top right, along with 30 seemingly emitted by clouds, and 40 going through the atmospheric window. The total outgoing radiation is used to back-calculate the "effective" temperature (-19°C) to derive the total "greenhouse" warming due to GHGs yet the radiation is coming from three different sources, presumably at three different temperatures. Methinks there's a rat in the woodpile.

Next, the 390 radiated by the surface is derived from a theoretical 15°C surface temperature,yet the diagram shows 24 + 78 = 102 lost by thermals and evapo-transpiration. That 102 is cooling the surface from its original state, so it can't be radiating 390.

Then there's the 350 from the surface shown as absorbed by GHGs. This illustrates that the atmosphere is "largely opaque" to LW IR, yet the downward 324 magically arrives at the surface, somehow avoiding all the molecules of GHGs on the way. Note that the downward 67 (from the sun) is absorbed, which can only be by GHGs, yet that 324 is not. There are a number of things going on in this diagram that appear to be uniquely directional.

Finally, the upward "165 emitted by atmosphere" (which must be from GHGs) is not balanced by the downward 324 from GHGs. If we take that at face value, it must mean that the two fluxes are coming from different layers of the atmosphere, at different temperatures. Both layers must radiate both up and down, or Kiehl and Trenberth know something about radiation that no one else knows.
Ernest Rutherford: "If your experiment needs statistics, you ought to have done a better experiment."
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#5
(07-05-2010, 02:21 AM)MostlyHarmless Wrote: Finally, the upward "165 emitted by atmosphere" (which must be from GHGs) is not balanced by the downward 324 from GHGs. If we take that at face value, it must mean that the two fluxes are coming from different layers of the atmosphere, at different temperatures. Both layers must radiate both up and down, or Kiehl and Trenberth know something about radiation that no one else knows.

Would it make any sense to reckon partial energy budgets for each layer of the atmosphere and then integrate them in a final one? I´m stuck with the idea that radiation must behave differently in each layer Huh

[Image: TH1G1.jpg]

LINK

Just a thought.
Ni cien conejos hacen un caballo, ni cien conjeturas una evidencia (F. Dostoyevski)
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#6
(07-05-2010, 04:41 AM)strogoff Wrote:
(07-05-2010, 02:21 AM)MostlyHarmless Wrote: Finally, the upward "165 emitted by atmosphere" (which must be from GHGs) is not balanced by the downward 324 from GHGs. If we take that at face value, it must mean that the two fluxes are coming from different layers of the atmosphere, at different temperatures. Both layers must radiate both up and down, or Kiehl and Trenberth know something about radiation that no one else knows.

Would it make any sense to reckon partial energy budgets for each layer of the atmosphere and then integrate them in a final one? I´m stuck with the idea that radiation must behave differently in each layer Huh

Just a thought.

See my reply to JohnWho on Re-radiation
The overall problem though, is that GHGs are shown in the diagram as absorbing IR selectively, i.e. from external sources, but not from their own molecules. Whether the effect is from "nullifying" or cancelling out of up-and-down fluxes in the "central bulk" of the atmosphere, or re-absorption of IR in this central bulk, GHGs cannot be radiating all that downward energy.

A Stefan-Boltzmann calculation shows that a perfect black-body at 2°C radiates 325 W/m², so the diagram must assume an "average" temperature very close to that. We know that the atmosphere only has this temperature in a relatively thin layer, so the radiation in the diagram must be coming from very many such thin layers at different temperatures. But each of those layers must be radiating both up and down. If there is a net downward radiation of 324,then there has to be a net upward radiation of 324 also, yet the diagram shows only 165 radiating to space.

In any case, the 24 W/m² shown for thermals is tiny. Better brains than mine have pointed out that this isn't enough to drive the convection known to exist close to the surface.
Ernest Rutherford: "If your experiment needs statistics, you ought to have done a better experiment."
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#7
Quote:I suggest we use this thread to produce a list of agreed errors or inconsistencies in the diagram, as suggested by Derek elsewhere. Perhaps I could use this post to create and add to the list?

Sure go ahead.

This is a subforum titled What About Backradiation?

A forum just for the purpose of examining and exploring information about Backradiation.

I will be transferring some threads that specifically cover this area from the main science forum to here.
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
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#8
What about this exciting chart?

[Image: ?ui=2&ik=091a54c27a&view=att&th=129a22b3...isp=emb&zw]

"Based on the K-T budget, it better distinguishes incoming from outgoing and indicates that the atmosphere magically jumps to a radiant strength of 519 watts per square, which it unequally distributes."
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
#9
(07-04-2010, 03:12 PM)Sunsettommy Wrote: Claes Johnson on Mathematics and Science

In the comment section.There is a man named Roger,who is providing a terrible defense of the backradiation accumulation effect.

He is obviously one of those AGW believers we have come to expect.He is being taken apart so easily it is sad that he seems unaware of it.

As Roger seems so beholden to the 1897 Arrhenius paper I tried to post the below, but couldn't.

Arrhenius ripped up his first paper in 1906.

Svante Arrhenius, 1906, Die vermutliche Ursache der Klimaschwankungen, Meddelanden från K. Vetenskapsakademien s Nobelinstitut, Vol 1 No 2, pages 1–10
Extracts online in - Falsification Of The Atmospheric CO2 Greenhouse Effects Within The Frame Of Physics Version 4.0 (January 6, 2009), Gerhard Gerlich and Ralf D. Tscheuschner
arXiv:0707.1161v4 [physics.ao-ph] (pdf pages 54 to 57) 4 Mar 2009
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.
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#10
Thank you MostlyHarmless, I´ll Keep on reading. I´m afraid I have to start from the beginning (that is, Divine Intervention).

SST, I cannot see the 2nd exciting chart.

Would it be useful to take into account what´s been said about energy budgets in the "dark side"? I have not read the 4 posts but it seems that next ones will tackle the K-T diagram, and they have been applying colorful thermodynamics lately.
Ni cien conejos hacen un caballo, ni cien conjeturas una evidencia (F. Dostoyevski)
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#11
AGW believer wet dream:

[Image: unphysics2.jpg]

Gosh when will they ever patent the creation of additional energy from the no free lunch machine?

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
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#12
I like the colours! Big Grin
Ni cien conejos hacen un caballo, ni cien conjeturas una evidencia (F. Dostoyevski)
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#13
A further fly in the ointment - notice that the surface reflects 30 of the 198 reaching it. This demonstrates that it is not a perfect black body absorber (which would absorb all incident radiation). I've already mentioned that the 324 "back radiation" is erroneously shown as all absorbed. From what I've read, so-called "grey bodies", i.e. those which do not absorb all incident radiation, will behave similarly when emitting. Taken at face value, this means that the surface would emit in the same proportion as when absorbing. That results in the surface actually emitting
390*(168/198) = 331
Even if the inherent assumptions about GHG absorption/back-radiation were true, this little lot means that K&T have got their sums badly wrong.
Ernest Rutherford: "If your experiment needs statistics, you ought to have done a better experiment."
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#14
From PhysicalGeography.net

Greenhouse Effect Illustrated

[Image: unphysics2.jpg]

Quote:Figure 7h-2: The diagram above illustrates the greenhouse effect. This process begins with the absorption of shortwave radiation from the Sun. Absorption causes the solar energy to be converted into sensible heat at the Earth's surface. Some of this heat is transferred to the lower atmosphere by conduction and convection.

Read the rest HERE

It gets worse fast as you read further down in the link.
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
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#15
tau........

Miskolczi (1.86) or NASA (from memory 2.13) figures.

AND, I can not resist a game of

"Spot the difference"....

[Image: unphysics2.gif]

[Image: 6a00d834519c3c69e200e553d605cf8834-.jpg]
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
#16
(07-05-2010, 05:24 AM)MostlyHarmless Wrote: See my reply to JohnWho on Re-radiation
The overall problem though, is that GHGs are shown in the diagram as absorbing IR selectively, i.e. from external sources, but not from their own molecules. Whether the effect is from "nullifying" or cancelling out of up-and-down fluxes in the "central bulk" of the atmosphere, or re-absorption of IR in this central bulk, GHGs cannot be radiating all that downward energy.

A Stefan-Boltzmann calculation shows that a perfect black-body at 2°C radiates 325 W/m², so the diagram must assume an "average" temperature very close to that. We know that the atmosphere only has this temperature in a relatively thin layer, so the radiation in the diagram must be coming from very many such thin layers at different temperatures. But each of those layers must be radiating both up and down. If there is a net downward radiation of 324,then there has to be a net upward radiation of 324 also, yet the diagram shows only 165 radiating to space.

In any case, the 24 W/m² shown for thermals is tiny. Better brains than mine have pointed out that this isn't enough to drive the convection known to exist close to the surface.

My poor brain is stuck with the same problem. I have shown calculations in Layman Struggles that there are enough CO2 molecules in the first 2,500 meters of the atmosphere to replicate a solid sheet of CO2 one millimeter thick. This should certainly stop all radiation specific to CO2 going up and coming down. The atmosphere is much deeper than 2,500 meters so there are more layers up the air column. If you accept 50% is backradiated from each layer you get the same answer for a CO2 layers at 100 meter intervals!!! Changing the amount of CO2 only changes the effective height of each layer, not the amount of back radiation.

If anyone knows of any specific studies please say. Don't bother with MODTRAN, those figures are derived from computer model simulations fed with data derived from laboratory experiments.

What is needed is the data from all the radiosonde balloons recording temperature and pressure and air flow ect. around the world. So far I have not read of any results that negate the currently understood adiabatic lapse rate.
Environmentalism is based on lies and the lies reflect an agenda that regards humanity as the enemy of the Earth. - Alan Caruba
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#17
(07-06-2010, 04:01 AM)Richard111 Wrote: What is needed is the data from all the radiosonde balloons recording temperature and pressure and air flow ect. around the world. So far I have not read of any results that negate the currently understood adiabatic lapse rate.

Indeed, and it's been shown that the lapse rate fits conductio/convection rather than surface radiation.

Don't fall into the trap of just considering CO2 though - water vapour is around 50 times the concentration of CO2 (more over water) and absorbs over more and broader IR bands, so its effect must be more than 100 times that of CO2. I've seen an estimation that all LW IR is absorbed well within the first 100 metres above the surface. Increasing GHGs would just lower that ceiling.

Somewhere, some time ago, I read a simple (to the author, anyway) mathematical analysis showing that CO2 molecules were so dispersed that they had a much lower chance of absorbing IR photons than a simple concentration calculation implies (i.e. water vapour masks CO2 physically as well as spectroscopically) . Extending this idea would suggest that only water vapour plays a significant role, CO2's role is tiny (we already know it's small), and therefore you could simply forget CO2 and the other trace GHGs.

If that 100 metre ceiling is correct, then the temperature of the emitting gases cannot be the 2°C that 324 W/m² implies. This radiation jigsaw doesn't fit together, and doesn't match the picture on the box.
Ernest Rutherford: "If your experiment needs statistics, you ought to have done a better experiment."
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#18
(07-06-2010, 04:01 AM)Richard111 Wrote: If anyone knows of any specific studies please say. Don't bother with MODTRAN, those figures are derived from computer model simulations fed with data derived from laboratory experiments.

Well said Richard111 - another major topic that needs far more and better explained exposure.
The "measurements" so often used / quoted are NOT measurements at all.
They are AT BEST guesstimates, based on PC (read pro AGW) assumptions.
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
#19
(07-06-2010, 04:51 AM)MostlyHarmless Wrote:
(07-06-2010, 04:01 AM)Richard111 Wrote: What is needed is the data from all the radiosonde balloons recording temperature and pressure and air flow ect. around the world. So far I have not read of any results that negate the currently understood adiabatic lapse rate.

Indeed, and it's been shown that the lapse rate fits conductio/convection rather than surface radiation.

Don't fall into the trap of just considering CO2 though - water vapour is around 50 times the concentration of CO2 (more over water) and absorbs over more and broader IR bands, so its effect must be more than 100 times that of CO2. I've seen an estimation that all LW IR is absorbed well within the first 100 metres above the surface. Increasing GHGs would just lower that ceiling.

Somewhere, some time ago, I read a simple (to the author, anyway) mathematical analysis showing that CO2 molecules were so dispersed that they had a much lower chance of absorbing IR photons than a simple concentration calculation implies (i.e. water vapour masks CO2 physically as well as spectroscopically) . Extending this idea would suggest that only water vapour plays a significant role, CO2's role is tiny (we already know it's small), and therefore you could simply forget CO2 and the other trace GHGs.

If that 100 metre ceiling is correct, then the temperature of the emitting gases cannot be the 2°C that 324 W/m² implies. This radiation jigsaw doesn't fit together, and doesn't match the picture on the box.

Yes, what you read is true: The chance of absorbing IR photons by the carbon dioxide is quite low due to its exiguous mass fraction in the atmosphere.

I have made the calculations and the mean free path for a photon without "touching" a molecule of carbon dioxide is 48.02 m. It means that the photon travels an average of 48.02 m without being absorbed by a molecule of CO2.

The time the photon will take for leaving the atmosphere without "touching" a molecule of carbon dioxide is 0.411 seconds.

Fortunately for living beings on Earth, there are lots of molecules of water vapor (10000 ppmV - 50000 ppmV), nitrogen (780000 ppmV) and oxygen (208000 ppmV), and dust particles (highly variable) and other molecules that intercept photons before they leave the Earth.
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#20
Gosh! Welcome Nasif Nahle. I am sure you will be inundated shortly! Big Grin

This post here shows where my blundering layman investigations are leading me.

Looking forward to more comments from you.
Environmentalism is based on lies and the lies reflect an agenda that regards humanity as the enemy of the Earth. - Alan Caruba
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