ADIABATIC CHANGES OF MOIST AIR NEUHOFF 431 



behavior of expanding moist air was developed mathematically 

 more fully and brought into convenient arithmetical solution. 



At the same time Hertz 6 constructed his very practical diagram 

 which made it possible to determine graphically, by the use of 

 curves, the changes in condition of moist air, avoiding any compli- 

 cated numerical computations. 



Although this diagram served as a very convenient help in com- 

 putations, von Bezold 7 introduced into meteorology not only the 

 more exact mathematical development of the changes of condition 

 of moist air but also the graphic method of presentation by Clapey- 

 ron 8 in order to represent graphically the thermodynamic processes 

 going on in the atmosphere independent of any of the limitations 

 introduced by any assumptions. 



Von Bezold also first called attention to the fact that the processes 

 going on in the atmosphere are often not reversible except in a 

 very limited sense and that we have not always to do with strictly 

 adiabatic changes but with those that can be designated as pseudo- 

 adiabatic. 



W. M. Davis 9 afterwards sought by diagrams to explain the 

 changes of temperature arid the associated processes in the atmos- 

 phere in a manner similar to that of von Bezold but by the applica- 

 tion of another system of coordinates, in that he used a horizontal 

 line as the scale of temperatures but a vertical line as the scale 

 of altitudes. This latter method of presentation had been occa- 

 sionally used to graphically present the results of Glaisher's balloon 

 voyages. 10 



In recent times this method has been used by von Bezold for a 

 great variety of cases where it is important to represent the depen- 

 dence of any meteorological element on the altitude. In order to 

 represent the course of the temperature a diagram or network of 

 squares is used, in which the horizontal side corresponds to a change 

 of temperature of i° C, and each vertical side to a hundred meters 

 in altitude. 



Unfortunately, an extensive application of the theoretical results 



6 Hertz: Graphische Methode zur Bestimmung der adiabatischen Zustands- 

 anderungen feuchter Luft. Meteorol. Zeitschr., 1884, S. 421-31. 



7 von Bezold: Zur Thermodynamik der Atmosphare. Sitzungsber. der 

 Berl. Akad., 1888. 



8 Clapeyron: Ueber die bewegende Kraft der Warme. Pogg. Ann. 1843, 

 S. 446-51, 566-86. 



9 W. M. Davis: Ferrel's convectional theory of tornadoes. American 

 Meteorol. Journal, 1889, S. 344. 



10 Sprung: Lehrbuch der Meteorologie. Hamburg, 1885, S. 90. 



