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| Subject: "That would correspond to calculating the average phone number in the phone book." | |
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Author: Stephen |
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Date Posted: 14:21:15 03/21/07 Wed In reply to: Oropan 's message, "How to average....leftist style" on 17:39:16 03/19/07 Mon Bjarne Andresen is wrong. But he does add some interesting new spin tjat I hadn't heard before. Thanks for the heads-up. > >href="http://www.sciencedaily.com/releases/2007/03/0703 >15101129.htm">http://www.sciencedaily.com/releases/2007 >/03/070315101129.htm > >Source: University of Copenhagen >Date: March 18, 2007 > More on: Climate, Global Warming, Environmental >Issues, Geography, Math Puzzles, Computer Modeling > >Researchers Question Validity Of A 'Global Temperature' >Science Daily — Discussions on global warming often >refer to 'global temperature.' Yet the concept is >thermodynamically as well as mathematically an >impossibility, says Bjarne Andresen, a professor at >The Niels Bohr Institute, University of Copenhagen, >who has analyzed this topic in collaboration with >professors Christopher Essex from University of >Western Ontario and Ross McKitrick from University of >Guelph, Canada. > >It is generally assumed that the atmosphere and the >oceans have grown warmer during the recent 50 years. >The reason for this point of view is an upward trend >in the curve of measurements of the so-called 'global >temperature'. This is the temperature obtained by >collecting measurements of air temperatures at a large >number of measuring stations around the Globe, >weighing them according to the area they represent, >and then calculating the yearly average according to >the usual method of adding all values and dividing by >the number of points. > >Average without meaning > >"It is impossible to talk about a single temperature >for something as complicated as the climate of Earth", >Bjarne Andresen says, an an expert of thermodynamics. >"A temperature can be defined only for a homogeneous >system. Furthermore, the climate is not governed by a >single temperature. Rather, differences of >temperatures drive the processes and create the >storms, sea currents, thunder, etc. which make up the >climate". > >He explains that while it is possible to treat >temperature statistically locally, it is meaningless >to talk about a a global temperature for Earth. The >Globe consists of a huge number of components which >one cannot just add up and average. That would >correspond to calculating the average phone number in >the phone book. That is meaningless. Or talking about >economics, it does make sense to compare the currency >exchange rate of two countries, whereas there is no >point in talking about an average 'global exchange >rate'. > >If temperature decreases at one point and it increases >at another, the average will remain the same as >before, but it will give rise to an entirely different >thermodynamics and thus a different climate. If, for >example, it is 10 degrees at one point and 40 degrees >at another, the average is 25 degrees. But if instead >there is 25 degrees both places, the average is still >25 degrees. These two cases would give rise to two >entirely different types of climate, because in the >former case one would have pressure differences and >strong winds, while in the latter there would be no >wind. > >Many averages > >A further problem with the extensive use of 'the >global temperature' is that there are many ways of >calculating average temperatures. > >Example 1: Take two equally large glasses of water. >The water in one glass is 0 degrees, in the other it >is 100 degrees. Adding these two numbers and dividing >by two yields an average temperature of 50 degrees. >That is called the arithmetic average. > >Example 2: Take the same two glasses of water at 0 >degrees and 100 degrees, respectively. Now multiply >those two numbers and take the square root, and you >will arrive at an average temperature of 46 degrees. >This is called the geometric average. (The calculation >is done in degrees Kelvin which are then converted >back to degrees Celsius.) > >The difference of 4 degrees is the energy which drives >all the thermodynamic processes which create storms, >thunder, sea currents, etc. > >Claims of disaster? > >These are but two examples of ways to calculate >averages. They are all equally correct, but one needs >a solid physical reason to choose one above another. >Depending on the averaging method used, the same set >of measured data can simultaneously show an upward >trend and a downward trend in average temperature. >Thus claims of disaster may be a consequence of which >averaging method has been used, the researchers point >out. > >What Bjarne Andresen and his coworkers emphasize is >that physical arguments are needed to decide whether >one averaging method or another is needed to calculate >an average which is relevant to describe the state of >Earth. > >Reference: C. Essex, R. McKitrick, B. Andresen: Does a >Global Temperature Exist?; J. Non-Equil. Thermod. vol. >32, p. 1-27 (2007). [ Next Thread | Previous Thread | Next Message | Previous Message ] |