tag:blogger.com,1999:blog-1500584444083499721.post8952780351797648718..comments2024-03-24T09:28:42.755+01:00Comments on CJ on Mathematics and Science: Evidence of CO2 Warming Supplied in School Projects Claes Johnsonhttp://www.blogger.com/profile/07411413338950388898noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-1500584444083499721.post-46535121642595322342014-04-30T21:44:44.908+02:002014-04-30T21:44:44.908+02:00L is path length. Rather than set it to 1 meter, i...L is path length. Rather than set it to 1 meter, it would have a value of 1000m -10,000m (approx since pressure varies as well) as we look up into the sky (a slice of the troposphere).<br /><br />That 3+ order of magnitude difference is very significant and leads to emissivity near .2 rather than .01.<br /><br />cementafriend, yes, these curves can be approximated with complex formulas found in engineering text books, but you have not argued anything remotely convincing to suggest the physicists are wrong. When you have a good argument, consider publishing it in a bona-fide physics journal. [Hint, prepare an argument that actually addresses the physics behind the greenhouse effect, eg, Ramanathan/Coakley 1978.]Jose_Xnoreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-49587041332327619852013-03-02T15:45:04.558+01:002013-03-02T15:45:04.558+01:00Your direct experience gives valuable support to t...Your direct experience gives valuable support to the impression I get sitting in my chair and reading. Claes Johnsonhttps://www.blogger.com/profile/07411413338950388898noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-91495128678528526012013-03-02T13:38:19.170+01:002013-03-02T13:38:19.170+01:00Not in my calculations! The various factors in the...Not in my calculations! The various factors in the equation to calculate absorptivity and emissivity are complicated. There are logarithmic factors. Three given calculated factors in Perry's Chemical Engineering handbook are for temperatures in furnaces (1000, 1500 & 2000K). It is stated the factors are valid over a 2000fold range and these need to be extended or interpolated. Prof Nahle takes a different approach and refers to graphs of Hottel etc. The graphs I have go down to 100F and need to be extended down to the lower temperature in the atmosphere. <br />I personally have made measurements of heat loss from surfaces (pipes) of temperatures in the range 25 to 350C to atmosphere, in furnaces where flame temperatures are in the range 2000 to 3200C and various heat exchangers with gases in the range 150 to 1200C. <br /><br />My experience and calculations supported by experience indicate a) the absorptivity & emissivity of H2O vapor is much more important than CO2 - it is at least 10 times higher at the same path length and partial pressure. In the atmosphere the absorptivity of CO2 at 400pm is insignificant (my value is a little higher than Prof Nahle, however he may be correct)<br />b)in flames the major emissivity arises from particles.In gases flames to get high radiation it is necessary to have internal reducing conditions to crack CH4 to C*. I have improved flame emissivity from 0.45 (mainly from H2O) to 0.8 (mainly from C*) by design of gas burners<br />c) at surface temperatures of 50C and lower heat loss by convection is more important than by radiation. The alarmist assumptions about radiation is nonsense. Even in furnaces with flame temperatures of 3000C convection must be counted and can do damage with poor flame placement and control.<br />d) the term "radiative forcing" is meaningless. The driver of heat transfer is related to temperature difference. The absorption of a very small amount of radiant heat by the trace gas CO2 in the atmosphere has NO measurable effect on temperature. The heat of the atmosphere is eventually radiated to space at the top of the atmosphere by H2O (gas, liquid & solid), aerosols, particles & to a small extent by CO2. A cold atmosphere (say 220K) can not radiate back to a surface of higher temperature on earth (230 to 340K -supposed average 288K) Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-74949679236905420482013-03-02T08:56:53.652+01:002013-03-02T08:56:53.652+01:00Yes I know of Hottel and Leckner. Do they give sup...Yes I know of Hottel and Leckner. Do they give support if 3.7 W/m2 of radiative forcing from doubled CO2? Claes Johnsonhttps://www.blogger.com/profile/07411413338950388898noreply@blogger.comtag:blogger.com,1999:blog-1500584444083499721.post-73894879508007395482013-03-02T03:39:17.243+01:002013-03-02T03:39:17.243+01:00I think you are wrong about data on carbon dioxide...I think you are wrong about data on carbon dioxide. The so-called climate scientists and incompetent physicists have just ignored the huge amount of research by engineers, and chemical engineers in particular. You have referred to Prof Nasif Nahle in one of your posts. In his article “Total emissivity of carbon dioxide and its effect on Tropospheric Temperature” he references Prof Hoyt Hottel’s book “Radiant Heat Transmission” 3rd ed 1954 and a paper by Lechner B “The Spectral and Total Emissivity of water vapour and carbon dioxide” Combustion & Flame vol 17 no 1, 1971. The Thesis by Ihab Honna Farag MIT 1976 (supervisors Prof Sarofim & Prof Hottel) titled “Radiative Heat Transmission from non-luminous Gases- Computational study of emissivities of water vapor & carbon Dioxide” has a large list of references (about 145) including research articles by a number of Germans such as K Schack “Berechnung der Stralung von Wasser dampf und Kohlendioxid” Chemie Ingenieur Technik vol 42 no2 <br />Something of Prof Hoyt Hottel can be found here http://web.mit.edu/newsoffice/1998/hottel-0926.html<br />He developed, from his research work, an equation to determine the emissivity of gases containing water vapor and CO2 based on partial pressures and path length. This can be found in chapter 5 (Heat and mass transfer) of Perry’s Chemical Engineering Handbook. Hottel also developed graphs shown in books on Process Heat Transfer based on the equation to aid design before the advent of computers.<br />Anonymousnoreply@blogger.com