STUDIES IN' ATMOSPHERIC ELECTRICITY. 9 



tricity, I agree with Sohncke. Duly I consider in udclition, that the 

 contact of warm and cold air, the intensity of wind, and the amount 

 of dust are circumstances having no in-considerable bearing upon the 

 phenomena, especially upon the seasonal and diurnal variations. 

 Against Sohncke's theory, it has been objected that in winter it is 

 not seldom that the isothermal of 0° does not lie at all within the 

 atmosphere, and the explanation of the high potential at a low 

 temperature much below the freezing point, seems to present an 

 insurmountable obstacle to the acceptance of this theory. Again that, 

 if an inversion of temperature occurs, so that the freezing point is 

 reached at a cetain height from the surface, the potential gradient will 

 become negative, a result utterly contrary to experience. ^^ 



To the first objection we may reply that probably the isothermal 

 of 0° always exists in the atmosphere, when the weather is calm and 

 the sky is clear. Some instances of temperature measurements in 

 balloons, which point to the above conclusion, may be mentioned. 



On Xov. 10, 1900, after a few days' continuance of calm and 

 anticyclonic weather, and under a perfectly clear sky, Ebert'^ m 

 Munich measured the following temperatures : 4°.2 at 1975 m. 

 (8.5Ga.-9.11a.); T.l at 2160 m.; T.T at 2275 m.; 0°.5 at 2420 m.; 

 -3°.8 at 2890 m.; -4^7 at 2965 m. (I0.38a.-10.53a.). On Jan. 17, 

 1901, under similar conditions, the same observer^^ measured: -15°.2 

 at the surface (524 m.?) ; r.2 at 842 m.; (9.18a.) ; r.6 at 995 m.; 

 3°.0 at 1275 m.; 4°.4 at 1470 m. (10.02a.-10. 17a.) ; 4°.5 at 1550 m.; 

 4°.8 at 1650 m.; 3°.8 at 1930 m.; 2M at 2285 m.; r.7 at 2375 m.; 

 r.7 at 2560 m.; 0°.3 at 2880 m.; -r.O at 2930 m. (0.11p.-0.17p.); 



1) Elster u. Geitel, Zusaumienstellung d. Ergebnisse neuerer Arbeiten ü. atmosphärische 

 Elektricität. p. 11. 1897. 



<■>) Ebert, Sitzungsberichte d. mithem.-phys. Clisse d. kgl. bayer. Akad. d. W. XXX. p. 



511. 1900. 



3) Ibid. XXXI. p 35. ICOl. 



