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Post by steve on Nov 23, 2010 18:02:02 GMT
If the line is from 14µm to 15µm the CO2 will absorb energy emitted from the ground between 14µm and 15µm.
If the line is from 13.5µm to 15µm the CO2 will absorb energy emitted between 13.5µm and 15µm.
As long as there *is* radiation between 13.5µm and 14µm being emitted from the ground, the broader line will absorb more radiation.
It *may* translate to a warmer atmosphere if the atmosphere has to warm to get rid of the increased energy it is absorbing. Calculations suggest that the earth's atmosphere would need to warm to get back in balance.
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Post by af4ex on Nov 23, 2010 18:15:44 GMT
Translation: "I will now show you how to 'amplify' money. Just spend it more slowly so that the spending 'stretches out' over a longer period. There, now you have a lot more money, and can buy a lot more stuff now, because you have stretched it out. We call this 'money broadening'."
Please don't waste our time and bandwidth with these specious arguments. I really am at the limits of my patience with you.
You really are behaving like a troll and are starting to disrupt this forum. Edit: I retract that last line, but you are trying my patience. Here's what you need to do to retrieve some credibility with this group. 1. Report back what _you_ found in the line-broadening literature, since you claim to have experience and expertise there. Or say "I couldn't find anything to support my claim in the literature either". 2. If you want to start your own analysis of this, fine! But we've seen enough qualitative hand-waving. We get the basic concept. Now _quantify_ it in terms of energy and thermodynamics. As I've said all along I can't deny it's true, but I want to see some convincing proof. Let's see some numbers and equal signs.
This is heat transfer, so explain how it works at the molecular level, in terms of probabilities and energy.
And remember you need to show how the amount of warming is amplified, not merely spread out ("diluted"), so try to quantify the amplification factor. :-|
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Post by steve on Nov 24, 2010 9:44:07 GMT
You say this,
at my simple explanations, and ask for quantification. I've given you what quantification I can with references to the Modtran calculator. But you have not responded to these posts.
You keep bringing this up. "Amplification" is entirely the wrong concept.
If you run the tap in a bath with the plug out, the water will reach a certain level where outflow equals inflow. Throw some hair in the plughole and the level will go up (and may stabilise at a higher level) as the outflow is cut down a bit.
Does the hair "amplify" the water level?
The temperature of the earth is dependent on balance having been reached between absorbed solar radiation and emitted infrared radiation. If you reduce the amount of emitted infrared radiation the earth will warm up until this balance is regained.
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Post by af4ex on Nov 24, 2010 13:02:00 GMT
> "amplification" We have shown that the GH effect of CO2 is demonstrably weaker on Mars. You (and other AGW folks) have said the GH effect on Earth wouldn't have this weakness because of "line broadening". Never mind the effect of water vapor, clouds, oceans, ice etc. Let's see some proof that "line broadening" makes the GH effect of CO2 "stronger" than on Mars. On Mars GH effect is neglible. On Earth it is often claimed that CO2, by itself, keeps the Earth from freezing. So that would be a (273-255) whopping 18C degree warming effect. Seems to me that represents some kind of "amplification" of the GH effect. Agreed? Let's not waste further time on what it should be called. Just explain the mechanism. I don't think spectral broadening has anything to do with this. I looked at your refererences (and my own) and saw nothing to back this up. Yes, other AGW sites make the same claim, also with hand waving. I think hyperphysics has the best explanation of broadening. hyperphysics.phy-astr.gsu.edu/hbase/atomic/broaden.htmlI guess I didn't make myself clear with the "money broadening". I was trying to present an equivalent argument so you could better see your broadening fallacy. Spectral lines are a lot like money in the sense that you can "buy" heat with them. But the purchasing power of money is fixed (unless you earn more ("magnify") wealth). Spreading it around might delay bankruptcy, but it doesn't magnify wealth. So, if you can buy a petajoule of energy standing at 14.77 microns, explain how we can buy 10 or 100 petajoules with same amount of absorption cash by "spreading it around". Truth is, these CO2 molecules are rather reckless in their purchasing habits. They buy up most of the terrestrial BB radiation within a few hundred meters of the surface. Then the buying spree is over. The free heat is gone and molecules cannot buy any more because of saturation (and the 2nd Law). Yes, there's some re-radiation and re-absorption, but the fact remains that the Earth's atmosphere is completely opaque to 14.77 micron radiation entirely due to "trace" amounts of CO2. Adding more CO2 doesn't make it any "opaquer". I think what you're saying is that spreading somehow (waving my hands) creates "new" absorption bands. Voila now we have bands between 13 and 16 microns etc with plenty of new heat to purchase with our pockets bursting with "unspent" cash. But wait, there's more! (As they say in the TV ads). We also have new absorption bands at 13.1, 13.2, 13.3,13.4....15.9, and 16.0 microns, all primed with heat and plenty of cash to buy this heat. Is that how it works? If so, show me an experiment where narrow-band 13 micron IR was transmitted through a tube containing 380ppm CO2 into an FTIR spectrograph. I would like to see the absorption spectrum. [Perform the experiment twice: Once for Martian conditions (i.e. without broadening) and once for terrestrial conditions (i.e. with broadening).] And you can't say "We'll use sunlight because it contains all wavelengths". That won't work because the absorption band at 14.77 microns will appear broadened and you'll take "credit" (no pun intended) for it. I'll admit I was wrong if you can show me this. I'm a skeptic. :-|
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Post by steve on Nov 24, 2010 14:42:40 GMT
Roughly speaking, yes, this is what I have said. The surface of the earth and Mars emit continuum spectra including emission in the infrared "window" that lies somewhere between 10 and 15µm. On earth, water vapour emits some radiation in this region too. Therefore a broadening of the CO2 spectral line into this region (relative to the absorption spectrum on Mars) will allow the atmosphere to absorb more of the energy emitted by the earth (and the atmosphere). I have access to google and google images, not spectrometers. I googled images for "co2 absorption spectrum". Eg. www.wag.caltech.edu/home/jang/genchem/infrared.htmWith respect to your comment: The wider absorption band in the earth's atmosphere will absorb a broader range of frequencies, yes. (In response to what looks like an additional point you have made: while wavelengths around the middle of the band are pretty opaque if you are trying to look from space all the way to the surface, they are not completely opaque - you will be able to see some depth into the atmosphere, and this depth will depend on the concentration of CO2.)
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Post by af4ex on Nov 24, 2010 15:24:59 GMT
Ok, we have enough details on what effects a "line broadening warming magnifier" (if it really exists) would have, hypothetically, i.e. the "hand waving" part of the theory. Let's not dwell on this any further. Now find the experimental proof, along the lines that I sketched, to prove that it really exists. I've actually looked for 'broadening increased warming' results, but nothing significant pops out. But perhaps I was looking in the wrong places. You claim expertise here (and it was your idea to begin with) so if you plan to spend further time here [and you're entirely welcome to do so if it continues the constructive research of these ideas] please help us out here. Fortunately, we have an excellent experimental control (the planet Mars) to discriminate between appearances and reality. I'm surprised the AGW folks haven't run such an experiment, because this "line broadening" stuff is mentioned in the AGW webosphere. ... or perhaps they did the experiments and don't want to talk about the results. Just saying. :-] [edit: BTW I provided you that same caltech reference on one of our very early posts. So who's not reading the all references here? www.wag.caltech.edu/home/jang/genchem/infrared.htm ]
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Post by steve on Nov 24, 2010 16:21:27 GMT
I'm not an expert. My knowledge of physics means that I believe that
- the spectral lines of CO2 in Martian atmosphere are narrower than those in the earth's troposphere, due to the lower pressure on Mars. - in the same way as it cools quicker on a clear, low humidity, night on earth due to lack of water vapour greenhouse effect, the narrower lines will allow faster cooling on Mars. - we know enough about gases to create radiation models that can estimate the transmission and emission of an Earth and Mars background. The calculations and observations from Mars roughly match up, and suggest that the Martian CO2 greenhouse effect is smaller than its weather variations, and the effect of the dust.
That's the extent of my "expertise" so I have nothing more to add.
I haven't looked in detail at the Lacis paper. The amount of warming induced by CO2 would only need to be sufficient to warm the tropics to above freezing - so less than 18C - as this releases water vapour which feeds back on itself till we reach the magically comfortable 287 Kelvin.
Analysis of the Mars atmosphere is not limited to AGW folk; I've found a few abstracts from astrophysical journals.
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Post by af4ex on Nov 24, 2010 16:44:31 GMT
steve> ... so I have nothing more to add. OK, you've given us an interesting hypothesis, which is begging for proof. Let's let some of the other readers chime in for a change. Does anyone out there have any further ideas concerning the validation of this hypothesis? [ ... crickets chirping ... ] [Read the last couple of pages, if necessary, to catch up on the details of this hypothetical 'Line-Broadening Warming Amplifer'. I'm tired of restating it. ] Thanks to all who have contributed to this discussion so far. Especially Steve, who has done most of the talking up to now. Perhaps that's why I seemed a bit testy. Sorry for any ruffled feathers. John/af4ex
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Post by icefisher on Nov 24, 2010 17:12:49 GMT
I haven't looked in detail at the Lacis paper. The amount of warming induced by CO2 would only need to be sufficient to warm the tropics to above freezing - so less than 18C - as this releases water vapour which feeds back on itself till we reach the magically comfortable 287 Kelvin. It seems to me you don't need a greenhouse effect to warm the tropics above freezing Steve. The average available insolation between 30N and 30S is above 400w/m2. That gets you about 290kelvin without any greenhouse effect not to speak of the diurnal variance which runs up during the day to about 1200w/m2 which without a waning sun would take you to above the boiling temperature of water. This is an example of how using averages is deceptive. We don't even measure surface temperature which is the temperature of the ground. Estimating everything is driven by CO2 is like suggesting an oil company's profits are driven by their petty cash accounts. And the AGW science community has chosen to not figure out the big effects and just ASS-U-ME that CO2 drives everything when they know nothing about why their models are failing. Just blow it off as weather and suggest their performance cannot be judged for a 100 years. I can't think of a better definition of a fraud. Of course braindead Schmidt et al assume that clouds are static as the greenhouse collapses without CO2. LOL!
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Post by af4ex on Nov 24, 2010 18:04:37 GMT
icefisher> It seems to me you don't need a greenhouse > effect to warm the tropics above freezing Steve. Thanks for the input icefisher. But you're confusing the AGW folks with reality, as opposed to what they claim: "the Earth would be frozen without CO2". Yes, they shot themselves in their own foot with their own bullet. Now the onus is on them to "prove" that CO2, by itself, has enough GH warming effect to thaw out the Earth. But it appears they can't, as the Mars Greenhouse has shown. So we get hand waving ("CO2-controlled-water-feedback") as they try to extract themselves from this self-inflicted wound. [edit: they should have listened to Arrhenius and Angstrom, back in the 19th century, who first dismissed the CO2 greenhouse effect.]
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Post by steve on Nov 24, 2010 18:30:10 GMT
Icefisher,
That's fine by me. I was responding to the suggestion by af4ex that the CO2 effect on earth *needs* to be at least 18C on its own.
I'm sure most climate scientists would take with a large pinch of salt any result from modelling of the earth with conditions so far out of anything we've measured. There's no religiously inspired *need* for CO2 to be all important.
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Post by af4ex on Nov 24, 2010 18:32:47 GMT
steve> There's no religiously inspired *need* for > CO2 to be all important. Except for the often seen claim that the Earth would freeze without it. Even the luke-warmers quote it.
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numas
Level 2 Rank
Posts: 94
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Post by numas on Nov 25, 2010 0:08:29 GMT
As a late comer to this topic, (having scanned the 9 pages of posts) I'd like to point out that the atmosphere makes the Earth MUCH cooler than it would be otherwise. So "greenhouse cooling" is about 100degrees when compared to the moon! We often forget that the main "purpose" of the atmosphere is to bring the diurnal variation into livable range.
The moon: Maximum temperature 123C Minimum: -233C Mean day: 107C Mean Night: -153 = Mean of -23 Celsius. Mean Variation:260degrees Absolute Variation: 356degrees.
Mars: Max: 20C Min -140C Mean -63C Variation: 160degrees.
Note that the Greenhouse effect is very active on Mars, as it never gets anywhere as cold as the moon - & since Mars is further away, we'd expect it to be cooler in the nights. The greenhouse gases are also responsible for moderating the daily maximum. Radiation works effectively to move heat sideways as well.
Part of the myth of AGW is the failure to see the dynamic of a spinning globe alternately warming & cooling.
As to pressure broadening, we should note that this must fall off very quickly with height on Earth, as temperature & pressure drop very quickly with height. We are left with the conclusion that the higher IR rises in the atmosphere, the easier it is to escape - and only close to the Earth's surface would there be any noticeable broadening.
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Post by steve on Nov 25, 2010 10:01:35 GMT
af4ex Well, we'd certainly get a new and severe ice age if all the CO2 got sucked away. As a late comer to this topic, (having scanned the 9 pages of posts) I'd like to point out that the atmosphere makes the Earth MUCH cooler than it would be otherwise. So "greenhouse cooling" is about 100degrees when compared to the moon! We often forget that the main "purpose" of the atmosphere is to bring the diurnal variation into livable range. The moon: Maximum temperature 123C Minimum: -233C Mean day: 107C Mean Night: -153 = Mean of -23 Celsius. Mean Variation:260degrees Absolute Variation: 356degrees. Mars: Max: 20C Min -140C Mean -63C Variation: 160degrees. Note that the Greenhouse effect is very active on Mars, as it never gets anywhere as cold as the moon - & since Mars is further away, we'd expect it to be cooler in the nights. The greenhouse gases are also responsible for moderating the daily maximum. Radiation works effectively to move heat sideways as well. Part of the myth of AGW is the failure to see the dynamic of a spinning globe alternately warming & cooling. It is true that the presence of an atmosphere moderates diurnal variations. AGW people don't "fail" to see the dynamic spinning globe. It's just that like most physicists they use thought experiments and the application of basic equations to simplified scenarios to get an initial handle on a problem. But since you mention diurnal variations, remember that the lunar night is 14 days long whereas the Martian night is 12 hours long. The dark side of the moon therefore has a lot longer to cool than the night side of Mars. It's valid to point out that pressure broadening varies with height - looking at the Modtran online calculator, that effect seems to be included as the line widths reduce with height. But the surface pressure of Mars is the same as the earth's air pressure at 35km up - well into the stratosphere.
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Post by icefisher on Nov 25, 2010 15:49:38 GMT
I'm sure most climate scientists would take with a large pinch of salt any result from modelling of the earth with conditions so far out of anything we've measured. There's no religiously inspired *need* for CO2 to be all important. Then explain the bogus science article on how the greenhouse effect would collapse without non-condensating GHG? Bottom line here is water vapor will not only rise above the warmest 60 degrees of latitude from insolation alone, winds will distribute it well into more latitudes. One can even support a notion of highly positive feedback with small amounts of water vapor in the sky. The condensating GHG turn to water block the entire spectrum of light, not just IR, and as they become more abundant turns the feedback to negative. Its pretty simple and consistent with most GHG theory except the Schmidt garbage. You even have a tipping point that is self limiting. The only difference is we are well beyond the tipping point already.
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