> PROCEEDINGS: PHILOSOPHICAL SOCIETY 397" 



wind convergence are marked by nimbus and more or less continuous 

 rainfall. Where such nimbus is formed the forced ascent of the air 

 may go to great heights and thus supply the fast upper winds with the 

 material for the drawn-out cirrus and cirro-stratus clouds that go far in 

 advance of the storm and later for the heavy alto-stratus. As the 

 center of lowest pressure goes by, perhaps not far to the north, an 

 underrunning wedge of cold air may, by raising the warm moist south- 

 westerly current above, bring on a few more hours of rainfall. This 

 cold wind carries strato-cumulus clouds, formed by the turbulence and 

 thermal convection, for perhaps a day, while the last of the long SW.- 

 NE. lines of alto-stratus and cirro-stratus clouds, forming by the under- 

 thrust of the lower wind which lifts the higher moist layers, gradually 

 pass over the eastern horizon. 



It is evident from studies of the appearance and transformations of 

 cloud forms that the different types of clouds are very closely inter- 

 related and pass from one form to another without any recognizable 

 dividing line. 



Since our weather is largely the result of the interaction of over- and 

 underrunning winds, clouds as indices of such are valuable in showing 

 what is going on and what is to be expected. Cloud observations are 

 finely complementary to pilot-balloon observations, for which there 

 must be clear air and a lack of even intermittently intervening clouds. 

 The whole domain of meteorology has no easier, more interesting, or 

 more promising aspect for observations and study than clouds. 



Discussion: In response to a question by Mr. Fenner, Mr. Brooks 

 stated that the cloud sequence during the progress of a cyclone was 

 different for different parts of the country. Mr. Humphreys called 

 attention to the unsatisfactory nature, from the scientific point of view,, 

 of cloud nomenclature. 



The meeting adjourned at 10.03 p-ni. 



S. J. Mauchly, Recording Secretary. 



