CHAP. !.(>. OP CLOUDS. 17 



The distinct formation of the cirrus is not 

 always a necessary precursor of the cirrocu- 

 mulus; the latter frequently forms primarily. 

 This may happen, perhaps, in consequence of 

 a supervening current of air, warmer than the 

 lower, and supersaturated with vapour, which 

 coming in contact with the colder one below, 

 is thrown into a state of aqueous gas, w r hich 

 from peculiarities in the electric state of the air, 

 may assume the cirrocumulative form. The 

 supposition that the cirrocumulus may be caused 

 by an upper current warmer than that below, as- 

 sists us to account for its being usually followed 

 by increased warmth. For many atmospheric 

 changes take place first aloft, and proceed down- 

 wards to the surface of our earth. 



SECTION VI. 



Of the Cirrostratus or Wanedoud. PI. II. Fig. 2. 

 CIRROSTRATVS. NVBES EXTENVATA SVBCOCAVA VEL 



VNDVLATA. NVBECVLAE HVIVS MODI ADPOSITAE. 



I OBSERVED, when treating of the cirrus, 

 that that cloud frequently changed into some 

 other. Its change is generally into either the 



c 



