2011-02-21 14:03:08John McLean Miscalculation
Alan

aj.flint@bigpond...
121.219.99.104

Thought you might be interested in another McLean rant that seems to have its basic physics that he claims to know so much about all wrong.

http://www.quadrant.org.au/blogs/doomed-planet/2011/01/alarmists-ignore-physics

Here he is claiming 1m of seawater has the same heat capacity of 3300m of atmosphere.

A few calculations seem to prove that the heat capacity he claims is out by a factor of 855. But it is a while since I did tertiary physics so I wouldn't mind a cross check.

Values for specific heat capacity Cp

Air: 1.0035 J/(g*K)

fresh Water: 4.1813 J/(g*K)

The density of air at  sea level and at 15°C according to ISA (International Standard Atmosphere), air has a density of approximately 1.22521 kg/m3.

At 3300m it is about 72% of sea level, basically linear reduction with height. So in the first 3300m density is an average 86% of SL or 1053.5 kg/m3.

1m of Seawater; density is 1025kg/m3, specific heat capacity 3993 J /kg/K @20 degrees.

                    water      air

SL  density/m3      1025        1.22521

density factor          1           .86

av/density kg/m3    1025           1.0535  

height                  1       3300

actual kg           1025        3663   

kj/kg/K             3993        1003.5

kj/K for "x"amount 
4092825
     

depth (m)            Kj/K of this mass       Ratio      

   1.225 0.86      3300  1057  1004  1060887     0.259 of water 1025 

       1025  1     1025  3993  4092825     3.857926    of air

                                                     

            seawater @20C     1025kg/m3                                

In other words the first 3300m of atmosphere has a bit more than a quarter of the heat capacity of 1m of water.

So McLeans conclusions as to relative heat capacities of atmospheric air to water are out by a factor of 3300/3.857926 or 855.

He can’t even claim a decimal point error with any more conviction than the rest of his bodgy unqualified theories.

Alan Flint