G. I. TAYLOR ON EDDY MOTION IN THE ATMOSPHERE. 21 



We have seen that 



BH^^+a. 



4 



If, therefore, we can measure a and Hj we can calculate B. The commonest value 

 for a on land is 20 degrees, in fact, for all except light winds, it is near to 20 degrees. 

 In the kite ascents on the " Scotia " the wind usually veered two points (22^ degrees) 

 in the first 100 or 200 metres and after that remained constant in direction at greater 

 heights. It appears, therefore, that on the sea also a is about 20 degrees. Assuming 

 then that a = 20 degrees, we see from Table III. that BE^ = 27. 

 Substituting for B its value 



/ 

 ^ 



sin X 



we find the following relation between H^ and the eddy viscosity 



fi _ H^w sin X 



; = (27)* 



But a), the angular velocity of the earth, is '00007 3 ; and in latitude 50 degrees N., 

 which is the latitude of the South of England and also of the northern portions of the 

 Bank of Newfoundland, sin X = 077. 



Hence for those regions - = H] 2 x 077 x 10~ 5 . 



P 



On land, in the case of the strong winds,* Hj = 900 metres, hence 



^ = 62xl0 3 inC.G.S. units; 

 P 



for moderate winds,* 



H, = 800 metres and nfp = 50 x 10 3 ; 

 and for light winds,* 



H! = 600 metres and p/p = 28 x 10 3 . 



At sea,t in the regions to which the "Scotia's" cruises were confined, H! commonly 

 lay between 100 metres and 300 metres so that /m/p lay between 077 x 10 3 and 

 6'9xl0 3 . 



* See Mr. DOBSON'S paper, loc. at. 



t Assuming that the wind had reached the gradient velocity when it had practically stopped veering 

 with increasing height. 



