ADIABATIC CHANGES OF MOIST AIR — NEUHOFF 453 



Sprung, in his Lehrbuch, has followed their course of reasoning 

 but in place of m he has introduced the quantities 



e = .3.44 I 1 + 0.258 ) in the dry stage 



c v + 0.622 Y d l 

 p dt 

 e = in the rain stage 



AR +0.622 - - 

 pT 



In the formula now developed we have to distinguish merely a 

 dry stage and a condensation stage which are separated from each 

 other by the temperature of saturation, which may equally well 

 be above or below o° C. 



If the condensation stage begins at temperatures above o° C. 

 then, when the air has cooled to the latter temperature and if the 

 condensed water remains in the air, the process of condensation is 

 interrupted by the isotherm of the hail stage, which must be con- 

 sidered as a special case by itself since its course is conditioned only 

 on the presence of liquid water in the air. 



This also can be at least approximately expressed in the general 

 form, when with the initial pressure at the end of the second or 

 rain stage we use the factor a u = 40.0 and with the final pressure 

 at the beginning of the fourth or snow stage we use the factor 

 a IV = 45.20. In place of the temperature term we have to sub- 

 stitute the term 



a e £= 1.82 £ 



which contains the quantity of moisture so that the isothermal 

 adiabat now reads 



log P' ~~= log p'o - - 1 ? -aj 

 P Po 



or 



/ 45-2 , , 40.0 t 00 ^ 

 log p' - — - = log p - —j- - 1 .82 e 

 P Po 



.(12) 



The exact formulae for the computation of the final pressure 

 from the associated temperature and the given initial condition 

 assuming adiabatic expansion of moist air are therefore as follows: 



