ADIABATIC CHANGES OF MOIST AIR NEUHOFF 



483 



Table 0. For initial pressure yso r ' 



Therefore for air that is saturated at its initial temperature of 

 30 and is ascending adiabatically the final temperature o° will be 

 attained at the following altitudes: 



7339 meters altitude for an initial pressure of 76o mm 



7359 " " " " " 75° mm 



7290 77° 



This indicates a difference in altitude of from 20 to 51 meters 

 or, for the same final altitude an uncertainty in the final tempera- 

 ture of o.i° or 0.2 . 



If we neglect this difference then the diagram gives the diminu- 

 tion of temperature with altitude for adiabatic expansion as inde- 

 pendent of the initial pressure. 



When pressures are to be read off from the diagram this difference 

 is' to be taken account of, that is to say, the initial point is to be 

 graphically transferred to the pressure line of the initial pressure. 

 This must always be done in fact for low pressures; for instance, if 

 we should locate 700™" initial pressure on the pressure line that is 

 marked 7<oo mm we must then diminish all the altitudes by this 

 difference with respect to the initial level. 



Of the many applications, that the diagram allows, we mention 

 especially the processes in connection with the occurrence of the 

 foehn wind. Whereas in considering ascending air it is almost 



