A CONTINUOUS RECORD OF ATMOSPHERIC NUCLEATION. 



91 



as this is concealed in a meastn-e by the specially computed 5-values. There is 

 reasonable agreement with the graph 2005', though the upper cycle lies above 

 it. In the d-cmves the agreement with .0029/5 is throughout as close as the 

 difficulty of observation permits. Three sweeping marches from violet to deep 

 red may be distinguished. 



In the last table (16) high pressure differences 6p = 22 cm. are brought to 

 bear, and the time intei'vals St = 2 and 4 minutes intervene between the ex- 

 haustions. A definite effect of the latter does not ax:)pear, since the nucleation of 

 the green coronas, for instance, is ;?= 107,000 and 1 18,000, with more nuclei indi- 

 cated for the larger time interval. The reverse would be the case if there were 

 marked time loss. The corresponding charts may be drawn to show the relations 

 in detail. The curve 4705^ lies above the higher coronas, whereas in the preced- 

 ing cases it lay below them, indicating the difficulty encountered in computing 

 sufficiently correct values for the subsidence constant, 5. While the n-values 

 show the ustial relations, the ti -values are more difficult to interpret; but three 

 cycles may be made oiit, with the middle one unusually bulging and contracted. 



29. Nucleation of the green coronas. — These values, though difficult to 

 obtain and suffering from cvunulative errors, are nevertheless consistent; and 

 the nucleation to prodtice the green corona seems to depend on the distance 

 between particles. Put d/n~" ' = D. Then the above results show that 

 n = io'(D— .01 14). Hence if the distance of particles is 87 times their diameter 

 the green coronas should appear for vanishing nucleations. This implies a limit 

 of values of n by which green coronas may be evoked. Furthermore, since the 

 apertures of this type of coronas remain within a range of values nearly the 

 same for all conditions of nucleation, the value of n may be found below which 

 green coronas do not occur. For the diameter of fog particle is here about 

 (i = . 00046 cm., and therefore «= 15,300. One may argue, therefore, that at 

 least 15,000 nuclei per cubic centimeter must be present if coronas of the middle 

 green type are to be possible. 



TABLE 17.— NUCLEATION OF 





THE GREEN CORONAS.' 



-.0114). 



n (computed) = 10 ■! (d^/n 



10" 



45 cm. (obs.) 

 8.5 cm. 

 .017 

 57 (comp.) 



46 cm. 

 17 cm. 

 .021 

 96 



47 cm. 

 22 cm. 



.023 

 113 



1 Earlier values, 5/) = 17 cm. and cubical vessel, io-')i =85, 106, 104, 96, and 96, 96, the mean being « = 

 97000. 



