XVI. 



ON THE THERMO-DYNAMICS OF THE ATMOSPHERE.* 

 (SECOND COMMUNICATION.) 



Bj Prof. Wilhei.m vox Bezold. 



Ill a memoir published several months siuce,f I made an attempt to 

 so extend the Olapeyron method of graphic presentation of thermo- 

 dynamic processes as to allow of its application to atmospheric 

 changes. At the same time I showed by some examples how with the 

 assistance of this method of representation even complicated 

 phenomena can be studied with comparative ease, and how by means 

 of it we are put in the position of being able to draw most important 

 conclusions almost like child's play. In the following, the same method 

 will be applied to other questions not then or only lightly touched upon. 



First, I will treat of a conception that has lately been introduced 

 into meteorology by von Helmholtz.f and which appears to me to 

 possess great significance in this science. This is the idea of 

 u warm egeh alt," or total amount of heat contained within a body. 

 Helmholtz measures the heat contained in a mass of air by the abso- 

 lute temperature that this same mass will assume when it is brought 

 adiabatically to the normal pressure. The quantity that we here deal 

 with is therefore not as one might easily have believed a quantity of 

 heat but a temperature, and therefore it seemed to me, upon my first 

 study of the memoir in question, desirable to replace the term " warme- 

 gelialt" by another. In a conversation upon this matter von Helm- 

 holtz recognized the objection expressed by me as proper, and proposed 

 that the word " wiirmegehalt" should be replaced by the evidently 

 much more proper expression "potential temperature." This latter 

 expression will therefore be used exclusively in thefollowiug memoir, but 

 at first this idea itself will be more accurately considered. Its presen- 

 tation in a diagram will be attempted and a general theorem deduced 

 from it. 



* Read before the Academy of Sciences, Berlin, November 15, 1888. (Translated 



from the Sitzungsberichte der Eonuj. Preuss. Akademiedtr Wissensch often zu Berlin, 1888, 



vol. xlvi, pp. 1189-1206.) 



t [See the preceding number of this collection of Translations. ] 



t "On Movements in the Atmosphere," Sitzb. Berlin A.kad., 1888, vol. xlvi, p. 647. 



[.See No. V of this collection of Translations. 1 



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