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Post by steve on Jul 16, 2011 15:25:28 GMT
This is a post to show to magellan, nautonnier and others that I am NOT DEAF!   The above plot shows the contribution to the cooling of the earth made at different wavenumbers (frequencies of light) and from different heights. It takes a bit of thought to interpret what the plot means, so I'll say what I think. The bottom of the graph is the surface, and the reducing pressure as you go up represents going up in the atmosphere. Going from left to right you increase the wave number which is the same as increasing frequency and energy of emitted photons. The pink stripe on the left is showing the amount of radiation being emitted into space from different heights in the atmosphere for different regions of the spectrum. The emission is attributed to water vapour. The reason the stripe goes down as you go to the right is that as the frequency increases the opacity reduces. ie. at the left of the stripe (at around 200cm-1) the water vapour in the atmosphere from the surface and up to 500 mbar may be emitting a lot of radiation, but it is absorbed by the water vapour above before it gets to space. As you go to 500cm-1 the opacity is reduced, so the radiation emitted at 700-800 mbar is getting to space. Also, there is less radiation emitted from water vapour higher in the atmosphere in this region of the spectrum. In the middle of this stripe is the CO2 line at 667cm-1. The CO2 at 200 mbar in height (about 12km in height) is absorbing all the radiation emitted from below, and the grey blob represents a contribution to the warming of the atmosphere. So in short, the AGW theory is as follows: 1. Increasing CO2 will increase the size of the grey blob that indicates the CO2 absorption *more* than it increases the size of the blue patch above the grey blob (that represents CO2 emissions to space) This is, in essence, a calculation of the so-called "no-feedbacks" response. 2. The important bit, and the bit that shows I really am listening is... The response of the atmosphere to the warming will result in a slight reduction of cooling from that huge water vapour stripe. ie. the pink and blue stripe will get a bit smaller. In fact what will happen is that the amount of water vapour will increase slightly. This will cause the whole water vapour "stripe" to rise a few 10s of metres (because more emission from the lower part of the stripe will be absorbed from the above part of the stripe). There will be less emission overall because the atmosphere is slightly cooler a few 10s of metres up. So to show I am listening to magellan et al YES it is EASY to pretend that our uncertainty about the huge stripe means that it is easy to pretend that the small CO2 blob is unimportant. But I think it is wrong to do so because there is definitely going to be a positive water vapour feedback. |
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Post by magellan on Jul 16, 2011 16:50:00 GMT
But I think it is wrong to do so because there is definitely going to be a positive water vapour feedback. Going to be? It isn't happened now where it should be happening, but oh the future.....just wait and see. I see you've latched on to Dessler's imagination. Do you actually think you've won the argument by that last sentence? How much does the greenhouse effect warm the surface? Is it 33 degrees? |
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Post by sigurdur on Jul 16, 2011 17:28:48 GMT
Steve:
In looking at the spectral emission chart, there is a slight flaw. Note the pink is broken by the gray band for co2. Yet, water vapor also absorbs in the co2 band.
The question becomes, what percentage of energy does not get through the h20 vapor to the co2? This is actually an important question that in my reading at least, I have not found the answer to.
I could be misreading the graph. I am going to try and find the paper that this graph originates from and read it to better understand the dynamics.
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Post by magellan on Jul 16, 2011 17:32:24 GMT
Steve: In looking at the spectral emission chart, there is a slight flaw. Note the pink is broken by the gray band for co2. Yet, water vapor also absorbs in the co2 band. The question becomes, what percentage of energy does not get through the h20 vapor to the co2? This is actually an important question that in my reading at least, I have not found the answer to. I could be misreading the graph. I am going to try and find the paper that this graph originates from and read it to better understand the dynamics. It would have been nice to link the graph. Aside from that sig, steve thinks Dessler has it all figured out. That's what his last sentence translates to. |
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Post by steve on Jul 16, 2011 17:54:12 GMT
Steve: In looking at the spectral emission chart, there is a slight flaw. Note the pink is broken by the gray band for co2. Yet, water vapor also absorbs in the co2 band. The question becomes, what percentage of energy does not get through the h20 vapor to the co2? This is actually an important question that in my reading at least, I have not found the answer to. I could be misreading the graph. I am going to try and find the paper that this graph originates from and read it to better understand the dynamics. The image shows a gap in the h2o ribbon below the CO2 blob. The water vapour ribbon would otherwise continue from 500-1000cm-1 without a break (probably). The point is that the water vapour emissions in this part of the spectrum are absorbed by the CO2 before they get to space. Do not think of radiation "getting through" the h2o. What is actually happening is that both h2o and CO2 are vigorously and continuously radiating and absorbing radiation in this region of the spectrum. It is just that the CO2 is more vigorous than the h2o in that part of the spectrum, and the CO2 is definitely more vigorous than the h2o at the altitude of the CO2 "blob". magellan, the main purpose of this thread is to try and get a shared understanding of what we are talking about so that we can avoid fruitless discussions that involve me being told that I apparently don't understand that water vapour is the most important greenhouse gas, or that I don't know that just a small change in clouds cancels out doubling CO2. |
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Post by steve on Jul 16, 2011 18:00:50 GMT
I think it is the following paper. But I'm more interested in the concepts exposed by the image than the details of the paper itself. www.agu.org/pubs/crossref/1995/95JD01386.shtmlJOURNAL OF GEOPHYSICAL RESEARCH, VOL. 100, NO. D8, PP. 16,519-16,535, 1995 doi:10.1029/95JD01386 Line-by-line calculation of atmospheric fluxes and cooling rates 2. Application to carbon dioxide, ozone, methane, nitrous oxide and the halocarbons S. A. Clough Atmospheric and Environmental Research, Inc., Cambridge, Massachusetts M. J. Iacono Atmospheric and Environmental Research, Inc., Cambridge, Massachusetts |
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Post by northsphinx on Jul 16, 2011 18:04:51 GMT
"line-by-line model (LBLRTM) has been applied to the calculation of clear-sky longwave fluxes and cooling rates for atmospheres including CO2, O3, CH4, N2O, CCl4, CFC-11, CFC-12, and CFC-22 in addition to water vapor. "
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Post by sigurdur on Jul 16, 2011 19:20:14 GMT
Steve:
Frm what I understand of the radiation spectrum, h20 is a better absorber and emitter than co2. I think what the graph is trying to show is that the combination of c02 and h2o bascially stop all radiation within the 12-16 micron range.
With that said, h2o within the stratosphere is quit thin. Something I will have to invesitgate is how much co2 is there as well.
Another thing this graph shows is that co2 only afects a very small micron range, yet we all know that the range of radiative transfer is much larger than the 12-16 that co2 supresses.
either side of these bands has a virtual free for all emission to outer space once they have been emitted in an upward direction by h20 with the exception of 03.
I am not familiar with the band that CH4 readiates, nor NO2.
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Post by steve on Jul 17, 2011 7:16:44 GMT
Steve: Frm what I understand of the radiation spectrum, h20 is a better absorber and emitter than co2. I think what the graph is trying to show is that the combination of c02 and h2o bascially stop all radiation within the 12-16 micron range. The graph makes it very clear that h2o is, over the whole range, more significant. But that also co2 is not unimportant and therefore should not be ignored. In terms of my reason for showing the graph I am concerned by your statement that "what the graph is trying to show is that the combination of c02 and h2o bascially stop all radiation within the 12-16 micron range" The reality is that radiation is continually being exchanged throughout the whole atmosphere column. In the light blue bits below the h2o band the h2o is roughly emitting and absorbing in equal amounts so there is not much net cooling. For a given wavenumber, as you go up in height into the darker blue and then pink bits, some and then more of the emission goes to space (and cools the planet). But also as you go up, the h2o is emitting less (because the pressure and temperature is dropping). So gradually the ability for radiation to escape is cancelled out by the reduction in the amount of radiation (at that wavenumber). Yes, but the h2o cannot choose where it emits! Within the co2 band the h2o is still emitting. It is just that it is overwhelmed by the co2. The fact that the cooling rate band widens at either side of the co2 peak is also indicative of the range of the co2 influence. Here, the cooling rate is partially down to h2o and partially to co2. If you increase the concentration of co2, then this will have an effect in these sidebands. Therefore this graph also undermines arguments about "saturation". |
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Post by steve on Jul 17, 2011 7:43:29 GMT
northsphinx
Just for info, while this data is from a radiation model, a radiation model is not the same as a climate model. These data have been validated by satellite observations.
Also remember that the satellite observations of atmospheric temperature such as those produced by Christy and Spencer at UAH are dependent on such "models".
Possibly you do not understand the plot, but the dark blue area at the top of the atmosphere makes the point that you make - that co2 acts also to cool the atmosphere. The point you miss is that it also acts to partially prevent the h2o from cooling the atmosphere, and that this effect is far bigger.
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Post by northsphinx on Jul 17, 2011 8:00:17 GMT
Take a close look at the CO2 spectra.
At 200mb it does absorb but below ans especially above that is it a cooling by CO2. (note the altitude, about 40.000 feet)
Adding more CO2 will according to Steve broaden the dark absorbing area but also the higher layer of cooling by CO2.
Which area is largest? Which effect will adding more CO2 cause?
In my simple eye comparison is the net cooling larger.
The argument that CO2 reduce outgoing from surface is not valid since the atmosphere is a fluid with convection so only average net radiation can be compared.
The figure show also very well that heat transfer of energy in the atmosphere are not radiative, only heat transfer from atmosphere to space are radiative. The energy that are lost to space are lifted inside the atmosphere by convection to emitting altitude. That little tiny aspect alone kill CO2 as a heating gas.
So are the result of more CO2 reducing or increasing outgoing radiation from the atmosphere? I can from the picture estimate that unfortunately is CO2 increasing cooling. That is a problem now when scientist and journalist have claim the opposite. It is now impossible to discuss CO2 cooling capacity.
This model show also another thing.
The significance of O3 is undervalued. Especially since it does not have a emitting capacity above the absorbing altitude.
Solar "produce" O3 from UV radiation. Solar UV intensity are changing much more than TSI.
With less UV from the sun will the upper atmosphere be cooler as with more CO2.
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Post by sigurdur on Jul 17, 2011 14:11:09 GMT
Steve:
You are correct in that my statement about blocking was not correct. Actually, that wasn't what I was thinking when I typed it as we all know that radiation goes in all directions.
Complete absorbtion of the co2/h2o overlap would have prob been closer.
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Post by steve on Jul 17, 2011 16:42:59 GMT
Take a close look at the CO2 spectra. At 200mb it does absorb but below ans especially above that is it a cooling by CO2. (note the altitude, about 40.000 feet) Adding more CO2 will according to Steve broaden the dark absorbing area but also the higher layer of cooling by CO2. Which area is largest? Which effect will adding more CO2 cause? In my simple eye comparison is the net cooling larger. Obviously, one cannot really know without re-doing the calculations with more co2, but my understanding is that the additional important effect of adding CO2 is that by broadening that dark blob, you are reducing the cooling effect of the h2o in the regions of the spectrum at the edge of the blob. Obviously you are wrong, since the "emitting altitude" for h2o in the waveband around 666cm-1 is below 500 mbar, but the "emitting altitude" for the co2 is above 200 mbar, which is way above the "emitting altitude" for most of the h20 cooling effect. I think the O3 band is entirely due to IR emission after the O3 is heated by incoming ultraviolet. Clearly there is not enough O3 to significantly affect the h2o cooling rate in this region of the spectrum. That is, below the co2 line there is a light blue stripe. But there is no light blue stripe below the O3 blob. |
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Post by sigurdur on Jul 17, 2011 17:07:46 GMT
Steve:
Ok......what the graph shows is that co2 absorbs and reflects at a higher altitude. However, when looking at the top of the graph, the heat escapes anyways with little overall net change.
Am I wrong in this?
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Post by sigurdur on Jul 17, 2011 17:09:41 GMT
The effect of removing co2 would be for the emission to be at the 800-900 mlb rather than at the 200 mlb?
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