Ixxxvi INTRODUCTION. 



ject of meteorological symbols, see Monthly Wcatlier Reviczv (Wash., D. C), 



May, 1 91 6, pp. 265-274. 



Table 113. Internationa! Cloud Classification. 



In the " International Atlas of Clouds and of State of the Sky, Abridged 

 edition for the use of Observers, Paris, 1930," the Commission of the Inter- 

 national Meteorological Committee for the Study of Clouds has proposed a 

 classification of clouds under Families A, B, C, and D, Forms a, b, and c, 

 and Genera i to 10 inclusive. But since the definitions of most of these latter 

 differ but little from those given in the International Cloud Atlas, 2d edition, 

 Paris. 1910, and since the new Atlas has not 3''et been generally accepted, the 

 well known definitions of the older Atlas are adhered to in Table 113. 

 Table 11 4. Beaufort zveafher notation. 



This table has been revised in the library of the United States Weather 

 Bureau, and represents the current practice of American and British ob- 

 servers in the use of the Beaufort letters. 

 Table 115. International code for horizontal visibility. 



The code for horizontal visibility is used by a large number of Nations 

 and was adopted by the International Commission for Air Navigation. 

 Reference : Convention relating to the Regulation of Aerial Navigation dated 

 October 13, 1919; corrected text of May 1929. The seat of the Commission 

 and of its permanent Secretariat has been fixed at No. 20 Avenue Kleber, 

 Paris. 

 Table 116. I^ist of meteorological stations. 



This list has been extensively revised, mainly by large additions for the 

 continents of South America,' Asia, and Africa. It includes stations for which 

 data appear in the " Reseau Mondial " of the British Meteorological Ofiice for 

 1922 (published 1929), which were selected to represent, as far as available 

 data permitted, the meteorology of all land areas of the globe, on the basis 

 of two, or in some cases three, stations for each ten-degree square of latitude 

 and longitude. Many additional stations are included for some countries, and 

 especially for the United States. 



No attempt has been made in this edition of the Smithsonian Tables 

 to indicate the " order " of the several stations, according to the definitions 

 adopted at the Vienna Congress of 1873; as, owing to the present wide- 

 spread use of self-recording instruments, the old distinction between first 

 and second order stations has lost much of its importance. 



Several stations included in the list are no longer in operation. Data 

 concerning the locations and altitudes of these stations are still valuable, 

 in view of the frequent use made of their records in meteorological and cli- 

 matological studies. 



In general, the established English spellings of geographical names in 

 foreign countries have been followed. Where no English name was established, 

 native orthography has been followed. 



