CYCLONES 



169 



does not blow directly into them, but produces great whirls 

 in which the air moves spirally inward and upward. 



The rate at which the wind blows varies in different 

 parts of the whirl, but is never very great. In the north- 

 ern hemisphere the rotary movement is in the direction 

 opposite to that in which the hands of a watch move, 



THE EFFECTS OF A TORNADO. 



The iron windmill was blown across the cellar and protected the people 

 who had fled there for safety. 



while in the southern hemisphere it is with the hands of a 

 watch. As these are areas of ascending air, they are 

 storm areas. The extent of the precipitation varies in 

 different parts of an area according to the direction from 

 which the ascending air has come. Note the direction 

 of the wind and the rainfall area as shown on the map 

 (page 172). 



Air which comes from the continental interiors is dry, 

 while that from the oceans contains much moisture, some 



