ADIABATIC CHANGES OF MOIST AIR NEUHOFF 451 



for example, we find for £ = 12.5 grams; m IV = 3.53 and for £ = 

 30 grams; m lv = 3.658. 



On the other hand, for the rain stage and £ = 30 grams we had . 

 m n = 3.881 and for the dry stage with g = 30 grams we had m l = 

 3.482. 



Therefore in the snow stage the influence of q on m is less than 

 in the rain stage. The coefficient a is a function of the tempera- 

 ture only; its value is given in table 6, column 6, for each degree 

 of temperature from o° C. to — 30 C. Thus, for instance, in the 

 snow stage for t = o° and for t = — 20 , respectively, we have 

 a = 45.20 and a = 10. c6. 



Thus the equation of an adiabatic line is easily and quickly 

 written to suit any special case. The solution of this equation 

 must be made by trial, which is, however, quite simple, when we 

 start with a correct estimate of the first approximate values. 



From the preceding it is evident without further explanation how 

 we obtain the total pressure p and the quantity of vapor x as well 

 as the volume of the mass of air. 



The diminution of the quantity of vapor with temperature is 



deduced from the following equation found by the combination of 



e 

 equation (11) with the value x = e — 



log x + a x + m lv log T — log e = constant 



where 



M r + r e 



AR T 



is to be taken from column a lv of table 6, column 4, as a function 

 of the temperature. 



The mass of air continues in the snow stage as long as no further 

 expansion takes place. As the initial pressure of the snow stage 

 occurs at the level where temperature is o° C. it is the same as the 

 final pressure at the end of the hail stage for which e = 4.6 and 

 p' = 47i.8 mm . If the expansion goes on until the temperature 

 becomes — 20 C. then for $ = 12.5 grams we obtain from table 

 4 the value m lv = 3.53. But since from table 6 for t = o we have 

 a = 45.2 and for t — — 20 we have a = 10.06, thereforefrom equation 

 (11) we obtain the final pressure p' = 311.5 and consequently 

 since e = 0.9"'™ we have the total pressure p = 312.4. 



The quantities are: vapor, x = 1.8 grams; ice, z =6.4 grams, and 

 snow, 5 = 4.3 grams. 



