380 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 5j 



Iii continuation of these views it is not difficult to form an idea 

 as to the extent to which the total kinetic energy actually present 

 in the atmosphere, e. g. in the shape of wind, can in an extreme case 

 affect these investigations. 



Assume that one kilogram of air is moving with the velocity v so 

 that the corresponding kinetic energy is 



--gh, 



where gh is the amount of work corresponding to this energy. If 

 this work is converted into heat it becomes 



h 

 424 



calories, an amount of heat that suffices to raise the temperature 

 of one kilogram of air under constant pressure by 

 h h " 



424 X 2375 de 2 rees Centl g rade or about 100 ae S rees - 



This latter number expresses the rise in temperature that the 

 air would experience if the wind could be suddenly brought to 

 a stop and it be then allowed to expand until equilibrium be attained. 



If v have values of 10, 20, or 30 meters per second then this warm- 

 ing would correspond to 0.05 , 0.20 , and 0.45 , respectively. 



But we estimate it too high when we assume that the mean 

 velocity of the whole atmosphere is 20 meters per second (10 meters 

 would be too high for the lowest stratum) and yet even so the sudden 

 conversion of the translatory motion of the whole atmosphere into 

 heat would cause a rise in temperature of 0.20 C. 



But this rise of temperature corresponds to an amount of heat 

 that would not suffice to evaporate a layer of water even one milli- 

 meter in depth. The potential energy that we observe in the form 

 of differences of atmospheric pressure, i. e., in superposed surfaces 

 of equal pressure, is of course of the same order as the actual energy 

 of translatory motion evolved from them, and thus we see that the 

 quantities of heat present in this form of energy are very small 

 in comparison with those that are absorbed and evolved in the 

 change of condition of water especially in its evaporation and 

 condensation. 



Hence in the determination of the total energy of any portion of 

 the atmosphere, the first matter to be considered is the quantity of 

 aqueous vapor contained therein. 



