tag:blogger.com,1999:blog-5337555368793819627.post6565786886907123566..comments2023-06-07T09:04:36.390-04:00Comments on More Grumbine Science: How CO2 mattersRobert Grumbinehttp://www.blogger.com/profile/10783453972811796911noreply@blogger.comBlogger10125tag:blogger.com,1999:blog-5337555368793819627.post-33268925874585863572009-11-14T09:28:47.218-05:002009-11-14T09:28:47.218-05:00There's a trade-off between transparency of co...There's a trade-off between transparency of corrections, and readability. You really don't need to cite me in the text at all.carrot eaternoreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-29681016659520609262009-11-13T20:46:59.531-05:002009-11-13T20:46:59.531-05:00S2:
Tyndall (I read his 1861 paper) did study the ...S2:<br />Tyndall (I read his 1861 paper) did study the absorption by a tube full of given gases. But as far as I saw, he didn't examine the temperature of the gases inside the tubes. If you have a citation to something of his (or anything else before 1900 that did) carrying out the experiment while checking temperature of the gas(es) inside the tube(s), please do post it.Robert Grumbinehttps://www.blogger.com/profile/10783453972811796911noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-2194545988852503082009-11-12T17:35:51.766-05:002009-11-12T17:35:51.766-05:00" I also believe that just such experiments w..." I also believe that just such experiments were done -- in the early 1900s."<br /><br />Actually I think it was John Tyndall in the 1860's.<br /><br />What I find interesting is that the number of atoms in a molecule is a pretty good indicator of how good a greenhouse gas it is likely to be. Anything with less than three atoms is pretty poor, at three atoms we start to see an effect (CO2, H20, O3, etc.) CH4 has 5 atoms and is (per mole) much more effective than CO2. I can see that this is because the quantum levels available increase as the number of atoms in the molecule increase.<br /><br />What I don't understand though is why nearly all the most potent GHGs contain Fluorine atoms.S2noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-86243947042005586332009-11-09T11:13:49.559-05:002009-11-09T11:13:49.559-05:00Carrot: Thanks for the correction. Sorry about be...Carrot: Thanks for the correction. Sorry about being slow to incorporate it.<br /><br />I tread lightly around the quantum mechanics stuff. It's hard to deal with both accurately and without the math. My hope is that by leaving it at vague verbal descriptions, readers realize that there's more going on -- rather than feeling a false sense of omniscience.<br /><br />I do like your aluminum foil analogy.<br /><br />Bcc: Thanks. The rambles, ..., well, I just hope that they cover interesting countryside. They're likely to happen. More than one friend has observed I could use an editor to keep the rambles in control.<br /><br />R. Test:<br />You have 2/3rds of what I think would be a good experiment. The third part would be a tube of just Nitrogen, Oxygen, and Argon. Shine the same infrared light through that. Then we see that it's the CO2 that's vital to the heating of the gases. I also believe that just such experiments were done -- in the early 1900s. I have to check the citations for the details. Or, of carrot eater is a.k.a. Eli Rabett, he can post the details himself.Robert Grumbinehttps://www.blogger.com/profile/10783453972811796911noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-80284368099046759422009-11-03T22:38:41.844-05:002009-11-03T22:38:41.844-05:00Well now that you've proven that Co2 can matte...Well now that you've proven that Co2 can matter even if its only 340 ppm of the sky, can you take on an even harder challenge?<br /><br />Prove that the sun matters to us. Its diamter is roughly 0.5 degrees. The skies diameter is 180 degrees, and 0.5/180 ^2 is roughly 8 ppm....Michael Haubernoreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-45468498918096078162009-11-03T20:20:20.946-05:002009-11-03T20:20:20.946-05:00Not being a scientist I don't know if any part...Not being a scientist I don't know if any part of this experiment makes any sense. Real Climate had something to say about this in another context a year or so ago.<br /><br />I think it addresses the issue: CO2 constitutes a "small" portion of the atmosphere.<br /><br />Experiment 1: a long tube containing x number of molecules of CO2 and no other gases. Shoot y number of photons into the bottom of the tube at a wavelength at which they will be captured by the CO2. Count how many come out the other end. <br /><br />Experiment 2: The same tube containing x molecules of CO2 and 99x molecules of a mixture of oxygen, nitrogen and argon. Shoot y photons and count how many come out the other end.<br /><br />I take it this would demonstrate something about the step between 2 and 3 in the less simplified model of the greenhouse effect.R. Testhttps://www.blogger.com/profile/11948928211339628650noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-16989737587170567092009-11-03T13:29:59.953-05:002009-11-03T13:29:59.953-05:00Good post (if a bit rambling toward the end). It&...Good post (if a bit rambling toward the end). It's surprising how often your garden-variety internet skeptic reverts to the "390 ppm is small" argument. <br /><br />I've been meaning to look up a toxic dosage that is << 390 ppm; arsenic in your coffee it is.<br /><br />I also like the # of CO2 molecules vs. photons framing. A little harder to explain than poisoned coffee, but a good fallback.BCCnoreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-45653968815446036222009-11-03T13:12:54.026-05:002009-11-03T13:12:54.026-05:00In case you find it interesting, I thought of a di...In case you find it interesting, I thought of a different way of presenting it. <br /><br />Say I hold up a 1 square meter piece of aluminum foil just over my head. I'll be most definitely be in the shade. Taking the thickness of a foil as 0.02 mm, I come up with 2 moles of aluminum in that foil. (hope my quick math was right). <br /><br />Nobody doubts that those 2 moles are enough to effectively block visible light; we have everyday experience with the optical properties of metals. So one should not be surprised if 90 or so moles of CO2, which absorbs IR, would also have some effect. If a material is absorptive or reflective enough, very small amounts of it make a difference.carrot eaternoreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-84785890500262106302009-11-03T12:51:48.845-05:002009-11-03T12:51:48.845-05:00Hmm. This isn't how I'd go about it, but ...Hmm. This isn't how I'd go about it, but it's a way.<br /><br />Some comments: Simply going from 10000 kg of air to 4 kg of CO2 seems to require all the components of air to have the same molecular weight, but they don't. Taking the average molecular weight to be 28.9 g/mol (dry basis), I get about 5.9 kg of CO2. Taking account of the average 0.4% or so water barely changes that. Doesn't affect the bottom line at all, but somebody might be annoyed by it.<br /><br />Also, your image of the disc is really more the projected area of a cylinder of air. All those molecules aren't actually in the disc; they're in the column above the disc.<br /><br />To keep it simple, you keep the quantum mechanics to vague verbal descriptions. But perhaps it'd be useful to just show the spectral molar absorptivities of CO2, water, nitrogen and oxygen, at whatever pressure. If nitrogen strongly absorbed at these wavelengths, nobody would care about a bit more CO2; then again, we also wouldn't be alive to worry about it.carrot eaternoreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-45760187204528973412009-11-03T04:51:11.803-05:002009-11-03T04:51:11.803-05:00correction on Avogadro's number: it's 6e23...correction on Avogadro's number: it's 6e23 (not 22). Which only serves to make your argument more convincing.quasarpulsehttps://www.blogger.com/profile/08762550806982089851noreply@blogger.com