WIND VELOCITY AND SURFACE PRESSURE — -GOLD 119 



morning observations. It was therefore possible to compare the 

 wind velocities observed with those calculated from measurements 

 of the gradient by the use of the' formula at the beginning of this 

 paper, the motion being assumed tangential to the isobars. 

 For purposes, of calculation the formula may be written 



v(l ±0. 00108 v cot dcosecJ) = 709 cosec /I T go 



x T B 



where <p is the angular radius of the small circle, on the earth's sur- 

 face, osculating the path, v is in meters per second, x is the distance 

 in kilometers between millimeter isobars, T, B axe the temperature 

 and pressure, and T , B the corresponding values for air at o° C. 

 and 76o mm . 



If the motion is along straight lines, cot (p = o, and the values of 

 v for B = B Q , T = T , are as follows if x = 50 kilometers: 



Latitude 3C° 



v 28 . 4 



If v represent the velocity when cot <J> = o, we can most easily 

 express the solutions of the equation for different values of 0, x, 

 X, by taking as independent variables, </>, v Q , X. 



Taking, as an example of the dependence on <//, X = 50 , v = 40 

 meters per second, we obtain the following values for v in meters 

 per second in the case of cyclonic motion : 



i/> 1° 2° 3° 4° 5° 6° 7° 8° 9° 10° 



v 17 21 24 26 28 29 30 31 31 32 



For anticyclonic motion the gradient corresponding to v = 40 

 meters per second is above the maximum, and we take for two ex- 

 amples v = 12, and v = 30 meters per second. 



The values of v are then as follows for the two cases: 



1° 2° 3° 4° 



For v = 12 v = = - - 20 



For 7,7. = 30 v = - - - - 



Where no value is inserted for v, the gradient corresponding to 

 the given value of v is above the maximum for the corresponding 

 value of (p. 



To show the dependence on X, we take (p— 3 and put v = 40 

 meters per second for cyclonic motion, and v = 10.5 meters per 



