SCIENTIFIC BALLOON ASCENSIONS VON BEZOLD 2Q7 



with it sufficient aqueous vapor, that a part of the work of expansion 

 is done by it so that adiabatic cooling is avoided. But after 

 passing the condensation limit and thereby entering upon unstable 

 equilibrium, the ascent goes on with increasing velocity, hence either 

 the whole condition must be different or else the movement must 

 come to a stop in consequence of the subsidence of the mass of air 

 cooled by ascent. 



On the other hand, similar processes are certainly possible under 

 anticyclonic weather conditions where in general the temperatures 

 diminish along a curve such as is represented by Z Z, but where in 

 between the descending masses of air others are ascending, whose 

 temperatures follow a different law, and thus may be explained the 

 occurrence of individual cumulus clouds that attain considerable 

 altitudes. 



If stratifications are present then, after the introduction of such 

 movements in individual cumulus clouds, masses of air may possi- 

 bly be drawn from the horizontal stratum that corresponds to its 

 base, which masses fill up the gap that would be left by the ascension 

 of the cloud. 



Finally it is also possible that counter currents may be caused by 

 the sinking of air in the neighborhood of the cumulus cloud. Of 

 course these must be quite dry when they reach the lower level and 

 thus cause dissolution or evaporation of the cloud. Numerous 

 observations made during the balloon voyages, showing relatively 

 great dryness when in gaps between the clouds or in the neighbor- 

 hood of cumuli, seem to be in harmony with this conclusion. 



At least the case represented by fig. 38, as plausible, seems to be 

 worthy of consideration. 



According to what has already been said, one easily recognizes that 

 the play of ascending and descending currents of air will suffice to 

 bring about a diminution of temperature with altitude. The prob- 

 lem is to ascertain to what extent the diminution actually observed 

 in scientific balloon voyages is really explained as to direction and 

 quantity by the above-given cause. 



If the diminution of temperature with altitude is simply a conse- 

 quence of ascending and descending currents, then must the average 

 temperatures of different altitudes be the average of those that 

 correspond to the ascending or descending branches of the different 

 currents that move in the same vertical. 



Under this assumption the course of the temperature is as shown 

 in general by fig. 39. 



If moist air ascends without increase or loss of heat, then the 



