SHORT MEMOIRS ON METEOROLOGICAL SUBJECTS. 



409 



after the nocturnal interruption. During the night-time even warmer 

 strata can float above the lower ones, cooled at the surface of the earth, 

 until the insolation is again active. In this manner, during calm, clear 

 summer weather, the entire lower portion of the atmosphere is quite 

 uniformly warmed and stirred up. 



If the ascending masses of air reach that altitude at which their 

 temperature agrees with that of the stratum attained, then should we, 

 during beautiful summer weather, observe a diminution of 1° C per 100 

 meters. This, however, is not the case, and the observations show, on 

 the contrary, that, at least in mountainous countries, the temperature 

 diminishes with the altitude slower during line weather than during bad 

 weather. This has already been proven by Kamtz from the tempera- 

 ture differences between Halle and the Erocken. In order to attain a 

 better insight into this relation, I have deduced the following numbers: 



An excellent monograph has been published by BillwilJer in Ziirich 

 on the thunderstorm of 28th July, 1S7U, in Northern Switzerland 

 (Schweiz. Meteorolog. Beobachtungeu, Jahrg. 1872). It therefore seems 

 to me most instructive to investigate the diminution of temperature 

 with altitude for the period immediately preceding this storm. Up to 

 the 19th July, the weather was cloudy and rainy ; the last rain fell on the 

 J9th, and on the 20th there began a period of beautiful hot summer 

 weather, which experienced its first interruption on the 28th by heavy 

 thunder-storms in the afternoon. 



Daily Mean Diminution of Temperature in degrees Celsius per 100 meters. 



During the rainy period, therefore, the upward diminution of temper- 

 ature was very large; on the advent of clear hot summer weather, it be- 

 came smaller, and, in fact, the diminution progressed quite regularly 

 from the beginning of the fine weather to the outbreak of the thunder- 

 storms, for instance: 



