OT: Climate sensibility

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Morris Dovey wrote:

I admit that I am not an expert in global warming, etc., and it has been a long time since I played with infrared spectrophotometers, but I will add a few comments to your posting. (This is usenet where anyone can post even even they do not know what they are talking about.)
I did a quick check using Google and I found your figure as part of a Wikipedia article: http://en.wikipedia.org/wiki/Sunlight.
I have no reason to doubt the figure. The figure shows the solar irradiance between 250 and 2600 nm. This range seems to cover most of the incoming solar energy. The figure shows that there is only a small effect of CO2 in received sunlight near 2000 nm.
However an important part of the 'greenhouse effect' is that sunlight comes in easily (as through the glass of greenhouse), warms the Earth which then radiates as heat energy in the infrared. If something blocks the infrared from being radiated back to space then the Earth will warm. Thus we need to look at the spectra of infrared light in the range emitted by the Earth.
The wavelength at which peak intensity is determined by lambda = B / T. Where B = 2.8977685 x 10-3 m K. This comes from http://en.wikipedia.org/wiki/Black_body
If we assume that the average temperature of the Earth is 20C or 293K then this gives us 9,890 nm. (I do not actually know the average temperature of the Earth so I just guessed but the value is probably accurate to within 10%.)
The figure that you gave does not cover anywhere near 9,890 nm. A little more Googling gave me this figure:
http://www.iitap.iastate.edu/gccourse/forcing/images/image7.gif
Like all data on the internet, I have no way to verify its accuracy. (However since it comes from an Iowa State University web site, I thought that you might give it a little more credence since ISU is reasonably local to you.)
The ISU figure shows major absorption by CO2 at around 2600 and 4000 nm and blocking beyond 13,000 nm. I think that the feature at 4000 nm was the one that I was seeing back when I was playing with infrared spectrophotometers.
The ISU figure indicates that water vapor, CO2, and methane all have effects upon the atmosphere's absorption of infrared and these three are generally listed as the major greenhouse gases. O2 and O3 also have their effects with the mjor feature between 9,000 and 10,000 nm. However I think that most people like the presence of O2 in the atmosphere.
My major reason for responding to Scott Lurndal's posting was his statement that "CO2 is a trace gas amounting to less than one tenth of one percent of the atmosphere." with its implication that such a small amount of the atmosphere could not have a major effect. As my experience with infrared spectrophotometers and the Iowa State University figure indicates, even a small percent of CO2 has major affects in the absorption of infrared by the atmosphere. That small percent of CO2 makes the atmosphere nearly opaque to infrared in certain frequency bands.
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Dan Coby wrote:

You are at least closer to being an expert than I. I'm not a physicist and my involvement with solar heating panel development has led me to focus almost exclusively on inbound energy and those aspects of absorption, reflection, and re-radiation in that limited (but still challenging) context.

It's the same figure - as I was trying to learn how to /design/ a super-efficient panel, I collected bits and pieces like this to mark my path. (Rather like dropping bread crumbs in the forest.)

It appears reasonable. I found several sets of independently produced measurements on the nasa.gov web site, and a number of similar plots based on those measurements, which seemed to agree - but I'm ignorant of how they determined which atmospheric components contributed to the "notches", since that info was outside of my 'focus'.

Yuppers - in a simplified view, we need to radiate as much back through the photosphere as passes inward - maintain an equilibrium...
...but I think it's not so perfectly simple for at least two reasons:
First, the planet has a significant internal heat supply which isn't perfectly insulated by the mantle; and second, the altitude of the blocking "something" may be significant - and I will be quick to say that I'm completely ignorant of the quantitative effect of either factor.

Another familiar page (which sent me off to study Planck's work, which made my head hurt) which provided some valuable clues to designing a thermal diode that could be produced in a woodshop.

I don't know, too, but can accept it as a starting point.

Proximity doesn't give 'em any edge on credibility, but immediately I'm interested in how the data was acquired, and what assumptions were made in producing the plots. For me the plots raise more questions than they answer - even when I assume that all their measurements were spot on.

Yuppers - I like O2 where I am and O3 overhead (I sunburn easily). I confess that I have difficulty finding the /significance/ of the absorption data as presented. My intuition tells me that the altitude distribution of these gases is not constant, and that there may also be geographical variances. I recall sailing in the Caribbean and noticing that, on an otherwise clear day, each island had its own cloud; and I'm aware that one side of a mountain range might be arid while the other side was wet. In my experience clouds seem to range from 1,000' up to about 50,000' - does that imply an altitude distribution for water vapor as well? Do those same kinds of distributions manifest for the other gases as well?

Perhaps because I lack your experience, I find myself with insufficient information to draw any conclusions about the significance of any change in atmospheric composition.
I provided the link, by the way, not to refute anything that you'd said but, rather, to provide what little information I happened to have that seemed germane. I especially appreciate the link to the ISU plots - they've certainly provided food for thought.
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Morris Dovey
DeSoto Solar
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Dan Coby wrote:

Good guess! I found 288K (or 15C / 59F) given for Earth's average surface temperature about 3/4 down the page at
http://en.wikipedia.org/wiki/Black_body_radiation
under the heading "Variables".
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On 12/15/2009 6:13 PM, Dan Coby wrote:

Please refer to the Infrared spectrum of Carbon Dioxide http://science.widener.edu/svb/ftir/ir_co2.html
To understand the scan remember that the x axis is in wavenumbers (2349=4.26 um) and 667.00 um.)
(See scan) While Carbon Dioxide is a strong absorber, it only absorbs in three small sections of the Infrared band. It does not absorb in the visible and Ultraviolet range.
The following is the same data for water vapor
http://en.wikipedia.org/wiki/File:Water_absorption_spectrum.png
There is 10 times the water vapor in the air and the bands of Carbon Dioxide have greater absorbance, BUT water absorbs in about 70% of the wavelengths in UV and Infrared, so because there is more total absorbance there would be more energy absorbed.
Sort of like the amount of water getting through a couple of pin holes in a bucket, compared to the water getting through a sieve.
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D'ohBoy wrote:

Why do you shout "GAS"?

According to which sources and why should we believe them? I'm sorry but "according to some sources" is meaningless.

What of it?

10 percent ain't much.

Uh, no.

So what?

What, you think you're going impress anybody with a big number?

Try to do better. Your effort in this post is pathetic.
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wrote:

ummm... do you know how much carbon dioxide we have been pumping into the atmosphere on an annual basis? It's in the billions of tons. ======================================================== Do you understand that methane is a far more serious greenhouse gas than CO2 and that cattle and other large mammals vent more methane into the atmosphere than any other source? Are you ready to wear a fart suppressor?
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. or eat less meat?
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On Wed, 16 Dec 2009 12:06:22 GMT, the infamous Bob Martin

Do you know how much methane is created by large amounts of cabbage? We should have outlawed Ireland years ago. <snort>
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wrote:

Do you know how much methane 8 Billion Vegans would produce?
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On 12/16/2009 8:24 PM, LDosser wrote:

OK, that was REALLY funny. You get a prize:
http://blogs.telegraph.co.uk/news/jamesdelingpole/100020126/climategate-goes-serial-now-the-russians-confirm-that-uk-climate-scientists-manipulated-data-to-exaggerate-global-warming /
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wrote:

http://blogs.telegraph.co.uk/news/jamesdelingpole/100020126/climategate-goes-serial-now-the-russians-confirm-that-uk-climate-scientists-manipulated-data-to-exaggerate-global-warming /
Too Kool! The Russians!
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The Russians have always said that man made global warming was bull.
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"LDosser" wrote:

Do you?
Lew
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It was a rhetorical question. Do you know what the climate was like Oregon during the last ice age. I do.
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On 12/16/2009 3:32 AM, LDosser wrote:

Carbon dioxide (CO2) forms approximately 0.04% of the nominal 5,000,000 billion of gas and aerosols that comprise the Earth's atmosphere. Only a small percent of the 0.04% of carbon dioxide in the atmosphere is contributed by man made activities.
http://en.wikipedia.org/wiki/Carbon_dioxide_in_Earth%27s_atmosphere
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Did you even bother to read that link?
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Keith Nuttle wrote:

The trouble is that in recent memory it has grown from .03 percent.
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wrote:

And has been ten times that in earth's memory, so what's the problem?
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LDosser wrote:

Perhaps you should ask someone who thinks that there is one.
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Sorry, I took the word 'trouble' to mean you thought there is a problem with the CO2 increase.
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