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Lessons in AGW (Read 4569 times)
Jovial Monk
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Re: Lessons in AGW
Reply #30 - Apr 5th, 2021 at 4:47pm
 
These questions, desperate lee, were asked very early in the piece.

Maybe this will help you understand?

Quote:
How does the Earth’s blanket of air impede the outgoing heat radiation? Fourier tried to explain his insight by comparing the Earth, with its covering of air, to a box with a glass cover. That was a well-known experiment — the box's interior warms up when sunlight enters while the heat cannot escape.(10) This was an over simple explanation, for it is quite different physics that keeps heat inside an actual glass box, or similarly in a greenhouse. (As Fourier knew, the main effect of the glass is to keep the air, heated by contact with sun-warmed surfaces, from wafting away. The glass does also keep heat radiation from escaping, but that's less important.) Nevertheless, people took up his analogy and trapping of heat by the atmosphere eventually came to be called "the greenhouse effect."(11*)      
Fourier


=>Other gases

Not until the mid-20th century would scientists fully grasp, and calculate with some precision, just how the effect works. A rough explanation goes like this. Visible sunlight penetrates easily through the air and warms the Earth’s surface. When the surface emits invisible infrared heat radiation, this radiation too easily penetrates the main gases of the air. But as Tyndall found, even a trace of CO2 or water vapor, no more than it took to fill a bottle in his laboratory, is almost opaque to heat radiation. Thus a good part of the radiation that rises from the surface is absorbed by these gases in the middle levels of the atmosphere. Its energy transfers into the air itself rather than escaping directly into space. Not only is the air thus warmed, but also some of the energy trapped there is radiated back to the surface, warming it further.
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Re: Lessons in AGW
Reply #31 - Apr 5th, 2021 at 4:48pm
 
Jovial Monk wrote on Apr 5th, 2021 at 4:47pm:
These questions, desperate lee, were asked very early in the piece.



And you still can't answer. Grin Grin Grin Grin Grin Grin Grin
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Re: Lessons in AGW
Reply #32 - Apr 5th, 2021 at 4:51pm
 
I am going through some of this website, desperate lee: https://history.aip.org/

It covers the history, desperate lee, of the development of climate science and understanding of AGW.
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Re: Lessons in AGW
Reply #33 - Apr 5th, 2021 at 5:07pm
 
Quote:
Fourier, Tyndall and most other scientists for nearly a century. . . .tended to think of the atmosphere overhead as a unit, as if it were a single sheet of glass. (Thus the "greenhouse" analogy.) But this is not how global warming actually works, if you look at the process in detail.      
What happens to infrared radiation emitted by the Earth's surface?

As it moves up layer by layer through the atmosphere, some is stopped in each layer. (To be specific: a molecule of carbon dioxide, water vapor or some other greenhouse gas absorbs a bit of energy from the radiation. The molecule may radiate the energy back out again in a random direction. Or it may transfer the energy into velocity in collisions with other air molecules, so that the layer of air where it sits gets warmer.) The layer of air radiates some of the energy it has absorbed back toward the ground, and some upwards to higher layers. As you go higher, the atmosphere gets thinner and colder. Eventually the energy reaches a layer so thin that radiation can escape into space.
     
What happens if we add more carbon dioxide? In the layers so high and thin that much of the heat radiation from lower down slips through, adding more greenhouse gas means the layer will absorb more of the rays. So the place from which part of the heat energy finally leaves the Earth will shift to higher layers. Those are thinner and colder layers, so they do not radiate heat as well.(11a*) The planet as a whole is now taking in more energy than it radiates (which is in fact our current situation). As the upper levels radiate some of the excess downwards, all the lower levels down to the surface warm up. The imbalance must continue until the upper levels get warmer and radiate out more energy. As in Tyndall's analogy of a dam on a river, the barrier thrown across the outgoing radiation forces the level of temperature everywhere beneath it to rise until there is enough radiation pushing out to balance what the Sun sends in.
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Re: Lessons in AGW
Reply #34 - Apr 5th, 2021 at 5:23pm
 
Jovial Monk wrote on Apr 5th, 2021 at 4:51pm:
I am going through some of this website, desperate lee: https://history.aip.org/

It covers the history, desperate lee, of the development of climate science and understanding of AGW.



No it is about the belief in AGW.

You can't refute petal. You have no credibility.

Even SKS you favoiurite source says it is likely rhat the net effects of clouds is positive. That is not something that has proven to be true. You just close your eyes, fingers in the ears and listen to your own little perturbations.

" The balance between the cooling and warming actions of clouds is very close although, overall, averaging the effects of all the clouds around the globe, cooling predominates."

https://earthobservatory.nasa.gov/features/Clouds

Ooops.
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Re: Lessons in AGW
Reply #35 - Apr 5th, 2021 at 5:37pm
 
Just going through the site which covers the history of the development of AGW science.
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Re: Lessons in AGW
Reply #36 - Apr 5th, 2021 at 5:59pm
 
Quote:
     
Arrhenius: Carbon Dioxide as Control Knob

     
These elementary ideas were developed much further by the Swedish physical chemist Svante Arrhenius, in his pioneering 1896 study of how changes in the amount of CO2 may affect climate. Following the same line of reasoning as Tyndall, Arrhenius pointed out that an increase in the blocking of heat radiation would make for a smaller temperature difference between summer and winter and between the tropics and the poles.      

Arrhenius's model used an "energy budget," getting temperatures by adding up how much solar energy was received, absorbed, and reflected. This resembled what his predecessors had done with less precise physics.But Arrhenius's equations went well beyond that by taking into account another physical concept, elementary but subtle, and essential for modeling real climate change. This was what one turn-of-the-century textbook called "the mutual reaction of the physical conditions" — today we would call it "feedback."(15)
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Re: Lessons in AGW
Reply #37 - Apr 5th, 2021 at 6:05pm
 
Jovial Monk wrote on Apr 5th, 2021 at 5:37pm:
Just going through the site which covers the history of the development of AGW science.



Yeah and how much it hasn't developed. 50 years of climate models and CMIP6 projections are hotter than CMIP5 models. No improvement in ECS in 40 years. And billions in funding. Wink
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Re: Lessons in AGW
Reply #38 - Apr 5th, 2021 at 6:20pm
 
Nice!

Quote:
An early example had been worked out by James Croll, a self-taught British scientist who had worked as a janitor and clerk in institutions where he could be near the books he needed to develop his theory of the ice ages.

Croll noted how the ice sheets themselves would influence climate. When snow and ice had covered a region, they would reflect most of the sunlight back into space. Sunlight would warm bare, dark soil and trees, but a snowy region would tend to remain cool.

If India were somehow covered with ice (or anything white), its summers would be colder than England's.

Croll further argued that when a region became cooler, the pattern of winds would change, which would in turn change ocean currents, perhaps removing more heat from the region. Once something started an ice age, the pattern could become self-sustaining.


Quite an insight!
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Re: Lessons in AGW
Reply #39 - Apr 5th, 2021 at 8:51pm
 
Quote:
Arrhenius: Carbon Dioxide as Control Knob
TOP OF PAGE      
These elementary ideas were developed much further by the Swedish physical chemist Svante Arrhenius, in his pioneering 1896 study of how changes in the amount of CO2 may affect climate. Following the same line of reasoning as Tyndall, Arrhenius pointed out that an increase in the blocking of heat radiation would make for a smaller temperature difference between summer and winter and between the tropics and the poles.      




Link from below

Arrhenius's model used an "energy budget," getting temperatures by adding up how much solar energy was received, absorbed, and reflected. This resembled what his predecessors had done with less precise physics.But Arrhenius's equations went well beyond that by taking into account another physical concept, elementary but subtle, and essential for modeling real climate change. This was what one turn-of-the-century textbook called "the mutual reaction of the physical conditions" — today we would call it "feedback."(15)      
An early example had been worked out by James Croll, a self-taught British scientist who had worked as a janitor and clerk in institutions where he could be near the books he needed to develop his theory of the ice ages. Croll noted how the ice sheets themselves would influence climate. When snow and ice had covered a region, they would reflect most of the sunlight back into space. Sunlight would warm bare, dark soil and trees, but a snowy region would tend to remain cool. If India were somehow covered with ice (or anything white), its summers would be colder than England's. Croll further argued that when a region became cooler, the pattern of winds would change, which would in turn change ocean currents, perhaps removing more heat from the region. Once something started an ice age, the pattern could become self-sustaining.
     
Arrenius stripped this down to the simple idea that a drop of temperature in an Arctic region could mean that some of the ground that had been bare in summer would become covered with snow year-round. With less of the dark tundra exposed, the region would have a higher "albedo" (reflectivity), that is, the ground would reflect more sunlight away from the Earth. That would lower the temperature still more, leaving more snow on the ground, which would reflect more sunlight, and so on. This kind of amplifying cycle would today be called "positive feedback" (in contrast to "negative feedback," a reaction that acts to hold back a change). Such a cycle, Arrhenius suggested, could turn minor cooling into an ice age. These processes were far beyond his power to calculate, however, and it would be a big enough job to find the immediate effect of a change in CO2.      

Arrhenius showed his physical insight at its best when he realized that he could not set aside another simple feedback, one that would immediately and crucially exaggerate the influence of any change. Warmer air would hold more moisture. Since water vapor is itself a greenhouse gas, the increase of water vapor in the atmosphere would augment the temperature rise. Arrhenius therefore built into his model an assumption that the amount of water vapor contained in the air would rise or fall with temperature. He supposed this would happen in such a way that relative humidity would remain constant. That oversimplified the actual changes in water vapor, but made it possible for Arrhenius to roughly incorporate the feedback into his calculations. The basic idea was sound. The consequences of adding CO2 and warming the planet a bit would indeed be amplified because warmer air held more water vapor. In a sense, raising or lowering CO2 acted mainly as a throttle to raise or lower the really important greenhouse gas, H2O.      

Then why pay attention at all to CO2, when water was far more abundant? Although Arrhenius understood the answer intuitively, it would take a century for it to be explained in thoroughly straightforward language and confirmed as a central feature of even the most elaborate computer models. The answer, in brief, is that the Earth is a wet planet. Water cycles in and out of the air, oceans, and soils in a matter of days, exquisitely sensitive to fluctuations in temperature. By contrast CO2 lingers in the atmosphere for centuries. So the gas acts as a "control knob" that sets the level of water vapor. If all the CO2 were somehow removed, the temperature at first would fall only a little. But then less water would evaporate into the air, and some would fall as rain. With less water vapor, the air would cool further, bringing more rain... and then snow. Within weeks, the air would be entirely dry and the Earth would settle into the frozen state that Fourier and Tyndall had pictured for a planet with no greenhouse gases.(16a
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Re: Lessons in AGW
Reply #40 - Apr 5th, 2021 at 9:15pm
 
That must be why Arrhenius amended his view in 1906.

"Much discussion took place over the following years between colleagues, with one of the main points being the similar effect of water vapour in the atmosphere which was part of the total fig-ure. Some rejected any effect of CO2 at all. There was no effective way to determine this split precisely, but in 1906 Arrhenius amended his view of how increased carbon dioxide would af-fect climate.  He thought the effect would be much less in terms of warming, and whatever warming ensued would be beneficial. He published a paper in German. It was never translated at the time or widely distributed, though many European scientists knew of it and read it."

I wonder why true believers never mention that? Wink
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Re: Lessons in AGW
Reply #41 - Apr 5th, 2021 at 9:21pm
 
Don’t they? I mention it. The extract I posted mentioned it.
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Re: Lessons in AGW
Reply #42 - Apr 5th, 2021 at 9:24pm
 
Jovial Monk wrote on Apr 5th, 2021 at 9:21pm:
Don’t they? I mention it. The extract I posted mentioned it.



No it doesn't petal. Why do you lie? Wink

"CO2 lasts for centuries" Grin Grin Grin Grin Grin Grin Grin Grin Grin
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Re: Lessons in AGW
Reply #43 - Apr 5th, 2021 at 9:25pm
 
It mentions water vapor, poor desperate lee.

Quote:
But climate is not a simple physical system. A true calculation of greenhouse effect warming requires measurements far more accurate and far more complete than Langley's. The details of exactly what bands of radiation are absorbed by CO2 and water molecules might have happened to be arranged so as to produce a markedly higher or lower amount of warming. As for theory, Arrhenius's model planet was mostly static. He deliberately left aside factors he could not calculate, such as the way cloudiness might change over the real Earth when the temperature rose. He left aside the huge quantities of heat carried from the tropics to the poles by atmospheric movements and ocean currents, which also might well change when the climate changed. Most important, he left aside the way updrafts would carry heat from a warmer surface into the upper atmosphere. In 1963, when a scientist made a calculation roughly similar to Arrhenius's, but with the aid of improved data on the absorption of radiation and an electronic computer, he found a far greater greenhouse warming — indeed impossibly greater. The assumptions left out too much that was necessary to get a valid answer.(19*)

Yet Arrhenius understood that he had not overlooked any terribly potent effect. Calculations aside, since the atmosphere keeps the surface of the Earth warm — in fact, roughly 40°C warmer than a bare rock at the same distance from the Sun — a few degrees sounded like about the right effect for a change in the atmosphere that modestly altered the balance of radiation. Arrhenius also knew that in past geological ages the Earth’s climate had in fact undergone changes of a few degrees up or down, not many tens of degrees nor mere tenths of a degree. While neither Arrhenius nor anyone for the next half-century had the tools to show what an increase of CO2 would really do to climate, he had given a strong hint of what it could possibly do.
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Re: Lessons in AGW
Reply #44 - Apr 5th, 2021 at 9:33pm
 
Jovial Monk wrote on Apr 5th, 2021 at 9:25pm:
It mentions water vapor, poor desperate lee.



So did 1896. Wink
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