tag:blogger.com,1999:blog-1500584444083499721.post1668528917637202745..comments2024-03-24T09:28:42.755+01:00Comments on CJ on Mathematics and Science: Bengtsson and Pierrehumbert: Back Radiation, Fossil Fuel and Pre-Industrial HellClaes Johnsonhttp://www.blogger.com/profile/07411413338950388898noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-1500584444083499721.post-65089146099231066712021-12-21T22:37:22.159+01:002021-12-21T22:37:22.159+01:00Claes--
Pierrehumbert says, "For present Eart...Claes--<br />Pierrehumbert says, "For present Earth conditions, CO2 accounts for about a third of the clear-sky greenhouse effect in the tropics and a somewhat greater portion in the drier, colder extratropics (see reference 9, figure 12.1); the remainder is mostly due to water vapor."<br />That's not "hand waiving", it's citing a source where the topic is presumably discussed further.John Diehlhttps://www.blogger.com/profile/10480963905273361685noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-82079146772224774082021-12-21T22:24:44.878+01:002021-12-21T22:24:44.878+01:00Thank you, Christopher, for the link to Pierrehumb...Thank you, Christopher, for the link to Pierrehumbert's paper. I read all of it; I think it's very good. I'm not a physicist; I think I somewhat understand some of it.<br />The fact that I understand very little of quantum physics is no indication that Pierrehumbert is using it "artistically". How well do you understand it?<br />If his use of the theory is wrong, how would one explain the close agreement between calculations based on it and observations (shown in the top panel of figure 3)?John Diehlhttps://www.blogger.com/profile/10480963905273361685noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-62903811182888448612015-03-04T17:46:33.890+01:002015-03-04T17:46:33.890+01:00The problem with the actual world is the fact that...The problem with the actual world is the fact that fossil fuels will be used in the future even more intense than today because many countries (especially developing ones) due to an increased demand of energy of any kind (fossil + green) produced by the overpopulation will burn more coal oil and gas to cover this increased energy demand.<br />I saw a recent prediction for the year 2035 that shows how the global energy mix will look twenty years from now:<br /><a href="http://www.alternative-energies.net/a-prediction-regarding-the-global-electricity-mix-in-2035/" rel="nofollow">http://www.alternative-energies.net/a-prediction-regarding-the-global-electricity-mix-in-2035/</a><br />Luckily, developed areas like North America, the EU, Eurasia and Japan will decrease the fossil fuel usage so we might have a chance.<br />Janenoreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-29590712658236862972015-03-04T16:25:47.833+01:002015-03-04T16:25:47.833+01:00Neither is any estimate made of the warming effect...Neither is any estimate made of the warming effect of the CO2 "ditch". Claes Johnsonhttps://www.blogger.com/profile/07411413338950388898noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-44511830959488514302015-03-04T16:04:24.273+01:002015-03-04T16:04:24.273+01:00Notable is the total effect of CO2 is claimed to b...Notable is the total effect of CO2 is claimed to be 1/3 of the "greenhouse effect" of 33 C, however without any support but hand waiving.Claes Johnsonhttps://www.blogger.com/profile/07411413338950388898noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-52029595759804635752015-03-04T10:24:49.442+01:002015-03-04T10:24:49.442+01:00An often cited paper by Ray Pierrehumbert is: &quo...An often cited paper by Ray Pierrehumbert is: "Infrared radiation and planetary temperature" (http://geosci.uchicago.edu/~rtp1/papers/PhysTodayRT2011.pdf)<br /><br />The following phrases are from the section of the paper defining "A Few Fundamentals": <br /><br />“At planetary energy densities, photons do not significantly interact with each other; their distribution evolves only through interaction with matter. The momentum of atmospheric photons is too small to allow any significant portion of their energy to go directly into translational kinetic energy of the molecules that absorb them. Instead, it goes into changing the internal quantum states of the molecules. A photon with frequency ν has energy hν, so for a photon to be absorbed or emitted, the molecule involved must have a transition between energy levels differing by that amount.<br /><br />Coupled vibrational and rotational states are the key players in IR absorption. An IR photon absorbed by a molecule knocks the molecule into a higher-energy quantum state. Those states have very long lifetimes, characterized by the spectroscopically measurable Einstein A coefficient. For example, for the CO2 transitions that are most significant in the thermal IR, the lifetimes tend to range from a few milliseconds to a few tenths of a second. In contrast, the typical time between collisions for, say, a nitrogen-dominated atmosphere at a pressure of 104 Pa and temperature of 250 K is well under 10−7 s.<br /><br />Therefore, the energy of the photon will almost always be assimilated by collisions into the general energy pool of the matter and establish a new Maxwell–Boltzmann distribution at a slightly higher temperature. That is how radiation heats matter in the LTE limit.“<br /><br />As I read the paper this is how Pierrhumbert describes the mechanisms for absorption of IR by CO2 and transferring the IR as energy to the other elements of the atmosphere.<br /><br />I am not able to follow his reasoning, To me it seems to be a kind of adjusting the physics to fit his cause by using elements from quantum mechanics in a rather "artistic" manner.<br /><br />I would appreciate your comments on the paper in general, and the way he applies basic physics in particular.<br /><br />Christopherhttps://www.blogger.com/profile/16081369039590413988noreply@blogger.com