a = 49. 3 



Observations made in nature show that the drift angle is actually almost 2 times smaller than 

 Ekman's theoretical angle. 



LITERATURE: 28, 30, 62, 64, 70, 72, 112, 164. 



Secfion 134. The Combined Influence of Winds and Currents 



We have seen that on an average we can assume the wind factor to be 0. 02 for close ice 

 fields. For the conversion of wind speed in m/sec into numbers on the Beaufort scale, let us take 

 a simple but sufficiently accurate formula 



w= 2n — 1, (1) 



where n is the wind force on the wind scale and w the wind speed in m/sec. However, 1 m/sec = 

 1. 945 knots or approximately 1 m/sec = 2 knots. Thus, 



c = 0. 04 (2n- 1), (2) 



where c is the speed of the wind drift of the ice in knots or 



C=2n — \ = w, (3) 



where C is the speed of the wind drift of the ice in miles/day. 



From table 103 in which the relationships between the wind force according to the Beaufort 

 scale and m/sec, and the wind drift speeds of the ice expressed in knots and miles/day, one can get 

 a good picture of the influence of the wind and the sea currents (excluding currents caused by this 

 same wind) on the drift of the ice. For example, if in a given region we observe a current (perma- 

 nent, tidal, gradient, etc. ) which reaches a velocity of 0. 5 knots, a wind force of at least 7 will be 

 required to cause the ice to drift against the current. On the other hand, a favorable wind will 

 correspondingly accelerate the drift. Some observed cases of ice drift can only be explained by the 

 above. 



It has been proven that there is a steady southeast current along the Chuckchee coast with a 

 velocity that reaches 1 knot. 



TABLE 103. RELATIONSHIPS BETWEEN WIND AND DRIFT 



366 



