OCEAN TEMPERATURES 363 



from the theory (pp. 355-360) are condensed in table 4, in which 

 the following values of the constants are used: 4 = 0, a 5 = .6, 

 <*! = .318, a 3 = .0244, a 2 = .0166, k .20, and H = 1.2 

 (1 .6 cos 30 ) equals the drift, in degrees per month equals 

 1.0 to 3.8 miles in twenty-four hours. The mean wind velocity in miles 

 per hour over the course considered (Moore, 1908-11) is approximately 

 .6 cos 



The rate of flow deduced from temperature data compared with that 

 expected from the empirical relation of winds to currents and with 

 direct observations on currents. 



As stated by Helland-Hansen in his paper on physical oceanography 

 (Murray and Hjort, 1912, p. 247) : 



The wind may produce a current, particularly in the surface layers, thus 

 altering the direction and velocity of the existing current. We know very 

 little, however, about the relation between wind and current, through lack of 

 detailed observations, although the question is naturally of the first importance 

 from an oceanographical point of view, as well as from its bearings on the 

 conditions of everyday life. This is one of the principal tasks for the ocean- 

 ographer of the future; such observations are difficult to make, no doubt, but 

 with modern methods much can be done. 



However, numerous observations of winds and currents have been 

 made. And, although the relation of wind and current varies with 

 the wind velocity, the latitude, coast line, depth, and distribution of 

 specific gravity, some progress has been made in estimating the drift 

 that a given wind velocity will produce. A careful investigation of 

 this question based on Ekman's theory (1905, 1906) and a large mass 

 of available data made by Thorade (1914) yielded the following 

 results. In case the coast is sufficiently distant and the effect of the 

 pressure gradient due to differences in specific gravity is small, the 

 drift will be directed at an angle of 45 to the right of the wind 

 direction in the northern hemisphere. The relation of the drift to the 

 wind velocity estimated by Thorade (1914, p. 387) is 



, (77) 



Vsin</> sec. hour 



and 



(78) 



, .. 



Vsin< sec. hour 



where V is the wind velocity, H is the current in meters per second, 

 and <f> is the latitude. 



