ADIABATIC CHANGES OF MOIST AIR — -NEUHOFF 



467 



Table E 



In general it is sufficient to adopt for C 2 in the rain stage an aver- 

 age quantity of moisture of 8 grams and corresponding to this use 

 the value C 2 = 103, whereas for the snow stage, in which only a 

 small quantity of moisture comes into consideration, we may put 

 C 2 = 101, the same as in the dry stage. 



In order to actually compute the altitudes according to the adia- 

 batic altitude formula for the condensation stage a knowledge of the 

 quantity of aqueous vapor (x) at the final condition is necessary 

 and this must be obtained by the method already described. But 

 it is not possible to deduce in a simpler form the expressions for 



and hence also 



dx dx 

 — or — 

 dt dh 



dt 

 dh 



for the condensation stage, since these values vary with pressure or 

 altitude and temperature. We can only establish more or less com- 

 plicated approximate formulae such as Hann has used for the com- 

 putation of his table for the value 



dt 

 dh 



and such as Sprung has given in his Lehrbuch. In general the 

 adiabatic hypsometric formula (18) presents in the simplest way 

 mathematically the law of the diminution of temperature with 

 altitude for the adiabatic expansion of air. The second term corre- 

 sponds to the change of elevation in consequence of the condensa- 

 tion of aqueous vapor and becomes o in the dry stage. 



