20 



Introduction to the Study of Science 



course of the winds about a low and a high pressure center, 

 we may now consider a particular instance. Take first the 

 low area and its accompanying winds. Observe on the map 

 that the winds are indicated as moving almost parallel with 

 the isobars in a direction opposite to that of the hands of a 

 watch or clock over the dial. This direction is generally de- 

 scribed as anticlockwise. Note also that the direction is 

 slightly inward or toward the center, even while keeping nearly 



Fio. 8. Graphic representation of areas of high and low pressure, with 

 the lows separated by a high-pressure ridge, R. Direction of winds indicated 

 by arrows. Compare with weather map of December 24, 1916. 



in alignment with the isobars. This is the essential point, the 

 generally inward and circular direction of the winds about a 

 "low." Because of this feature the low region is called a 

 cyclone, from the Greek word kuklos, meaning a circle. 



When you consider the high-pressure areas, you find exactly 

 the opposite condition. While moving clockwise and yet nearly 

 parallel with the isobars, the winds generally tend outward or 



