BULLETIIV 



OF 



THE CHARLESTON MUSEUM 



Vol. 7 CHARLESTON, S. C, OCTOBER, 1911 No. 6 



WEST INDIAN HURRICANES 



The most notable event of the summer in Charleston was the 

 destructive hurricane of August 27-28, and we trust that a brief 

 statement of the relation of these hurricanes to other kinds of 

 cyclonic storms, as well as a few observations on the effects of the 

 storm, may be of timely interest. 



Meteorology of Hurricanes 



^ In the temperate and colder regions of the earth the prevailing 

 surface winds are westerly. In the equatorial region the trade 

 winds blow from the northeast in the northern hemisphere and 

 from the southeast in the southern hemisphere. Areas of low 

 barometric pressure form as eddies in the prevaihng westerly 

 winds and move eastward in alternation with areas of high baro- 

 metric pressure. The air settles to the earth in a "high" and 

 spreads out in all directions in a spiral manner, forming what is 

 called an anticyclone. In a converse manner the winds blow 

 from all directions in a spiral path to the center of a "low," 

 forming a cyclone. The falling air of an anticyclone brings clear, 

 cool weather, while in a cyclone the warm, moist air from the sur- 

 face of the earth is chilled as it rises and precipitates its moisture. 

 Cyclones are therefore rotary storms of large area, usually a 

 thousand or fifteen hundred miles in diameter, and moderate in- 

 tensity. They are sometimes accompanied by local rotary storms 



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