96 flature'* /BMracie0* 



the areas and by the distance that the areas of 

 high and low pressure are apart. The steeper 

 the grade the more rapidly the fluid will flow. 



Let us now have recourse, for a moment, to 

 Figs. 1, 2, and 3 in order that the subject may 



South. 



(Jpp*r Air 



Lo *_ ^_ High 



FIG. 1. 



be more fully understood. In looking at these 

 diagrams we should imagine ourselves looking 

 South, with the left hand to the East. 



Fig. 1 shows the general direction of the air 

 movement between two areas one of high 

 and the other of low pressure. The arrows 

 show the general direction of the wind. You 

 will notice that in the upper regions it blows 

 in an opposite direction from the air move- 

 ment on the surface of the earth. 



Fig. 2 shows in a general way how the wind 

 moves spirally around both centers. Over 

 the area of high pressure the air descends 

 spirally from the upper regions, circling 

 around a large area it may be one hundred 

 miles or more in diameter in the direction of 

 the movement of the hands of a clock. 



