tag:blogger.com,1999:blog-16612221.post113254877001363871..comments2021-04-22T03:05:22.044-04:00Comments on Rabett Run: T(emperature) Rex bites Essex and McKitrick in the butt.....EliRabetthttp://www.blogger.com/profile/07957002964638398767noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-16612221.post-1143297431340624282006-03-25T09:37:00.000-05:002006-03-25T09:37:00.000-05:00John: Essex & McKitrick used Celsius (not Kelvin) ...John: Essex & McKitrick used Celsius (not Kelvin) for their calculations.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-16612221.post-1133047192532886032005-11-26T18:19:00.000-05:002005-11-26T18:19:00.000-05:00The geometric mean is the nth root of the product ...<I>The geometric mean is the nth root of the product of all the measurements. IF one of the measurements is zero, then the geometric mean is zero no matter what the other values are.</I><BR/><BR/>How can one of the measurements be zero if temperature is measured in Kelvin?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-16612221.post-1132634965471135742005-11-21T23:49:00.000-05:002005-11-21T23:49:00.000-05:00(Eli, would you please return to Stoat at some poi...(Eli, would you please return to Stoat at some point soon and explain in a bit more detail what the heck you meant about the new Mann paper admitting to some extent the M&M criticism relating to the bristlecones? Thanks.)<BR/><BR/>I've always been a bit mystified by E&M's choice of analogy. Did they not even try to go through a direct calculation of differences due to water vapor? Also, even if there was more to their point, of course what is mainly of interest is the temp anomalies rather than the absolute temperature, and it doesn't seem that having some number of stations with a wet or dry bias would change the anomalies meaningfully so long as there was some degree of continuity in the stations over the course of time.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-16612221.post-1132623612300693192005-11-21T20:40:00.000-05:002005-11-21T20:40:00.000-05:00Dave, we looked at the effect of water vapor on at...Dave, we looked at the effect of water vapor on atmospheric heat capacity a while ago on Deltoid, see http://timlambert.org/2005/06/barton/comment-page-5/#comments particularly comments 208, 217, 219, 225 and 235. The difference between the heat capacities of dry air and air with water vapor in it are quite small on a volume or molar basis. Take care and do not wake that Bahner beast.<BR/><BR/>More seriously, my plaint against Essex and McKitrick has two principal points which have little to do with water vapor. First, that if you are averaging temperature and you use anything BUT a arithmetic average you HAVE to use absolute temperature especially if you are looking at radiation. Second that there REALLY are good physical reasons for using arithmetic averages. The change in heat capacity for air between 200 and 300 K is zilch (1.007 J/gK see the CRC tables)<BR/><BR/>As an indication of what happens at higher temperatures you can calculate the heat capacity for nitrogen in J/(mol-K) using a Shomate equation<BR/>Cp° = A + B*t + C*t^2 + D*t^3 + E/t^2<BR/><BR/>Temperature (K) 298. - 6000.<BR/>A 26.09200<BR/>B 8.218801<BR/>C -1.976141<BR/>D 0.159274<BR/>E 0.044434<BR/>F -7.989230<BR/>G 221.0200<BR/>H 0.000000<BR/><BR/>(From webbook.nist.gov, a wonderful source of information on molecules, I DO get my money's worth from the taxes I pay!)<BR/><BR/>EnjoyEliRabetthttps://www.blogger.com/profile/07957002964638398767noreply@blogger.comtag:blogger.com,1999:blog-16612221.post-1132595550922581812005-11-21T12:52:00.000-05:002005-11-21T12:52:00.000-05:00From: http://www.cgd.ucar.edu/csm/models/cpl/cpl4...From: http://www.cgd.ucar.edu/csm/models/cpl/cpl4.0/doc9.html<BR/><BR/>Heat Capacity of air = 1.005 kJ/kg/deg K [no temperature given but I saw this other places for 20deg C)<BR/>Heat Capacity of water vapor = 1.810 kJ/kg/deg K <BR/><BR/>From my old CRC Chem Physics Handbook<BR/>vapor pressure of H2O at 5 deg C (278 deg K) = 6.543 mm Hg<BR/>vapor pressure of H2O vapor at 25 deg C (298 deg K) = 23.756 mm Hg<BR/>difference = 17.213 mm/1000mm/atm. = 1.72%. <BR/><BR/>If we assume therefore 98.28% regular air and 1.72% pure water vapor we get, at 25 Deg C<BR/><BR/>.987714 + .031132 = 1.018846<BR/><BR/>This is about a 1.4% increase in the Heat capacity of saturated water from 5 to 25 deg C. For a 20 degree change in temperature therefore we get a .28 deg difference in the recorded temperature between dry and saturated air (assuming, that the cold air could hold that much water which of course it can't, and ignoring that I should probably halve the difference to assume a linear change in heat capacity.) The point is that averaging the two conditions would result in different means. The difference is small, but so is the global warming amount. I think that rather than putdowns, you should try posting actual calculations with ALL the requisite differences, including the change in heat capacity for dry air at different temperatures which I didn't find in a quick look, and might be larger than the change from humidification. <BR/><BR/>Please note, I realize that typical actual examples will show less change from humidity, but I think I show you can't dismiss A&M as quite as simpleminded as you try. *Disclaimer, I haven't read their book so I might end up disagreeing with it too if I read it, but at least I wouldn't be as dismissive as you are.Dave Dardingerhttps://www.blogger.com/profile/12348781597231603410noreply@blogger.com