MOVEMENTS OF ATMOSPHERE GULDBERG AND MOHN 213 



and introducing a mean value of p we shall have 



D - - itk (I) 



If we suppose that the curve of the gradient can be represented 

 by two straight lines and if we express x in degrees of a great circle 

 we have 



D = lG x (2) 



The gradient G is determined for the velocity U by the known form- 

 ulae 



G p k 



U /< ' cos a 



2 co sin 6 

 tang a = ^~ 



consequently we have 



For example let 



2 U n cos a 

 x = — ^ (3) 



8 = 30°, 



k = 0.00004, 



we have 



It 



we shall have 



ex = 61.25 c 

 G : U = 0.09. 



D = 0.5 mm , 



U = about 7 m , 

 G = 0.63 

 x = 1.6° 



§30. Movable systems of wind 



When the barometric minimum or maximum changes its position 

 along the surface of the earth, the system of wind is called movable. 

 The movement of the barometric minimum or maximum is accom- 



