WEATHER SERVICE OF THE UNITED STATES 249 



279. Hurricanes. In the tropical part of the Atlantic, 

 north of South America, violent storms are developed, 

 called hurricanes. Similar storms in the Pacific and 

 Indian oceans are called typhoons. Both are great whirl- 

 ing masses of air, with a diameter of 300 miles or more, 

 in which the violence of wind and rain becomes enormous. 

 The "West India" hurricanes move northwestward until 

 they reach the southeastern coast of the United States; 

 then they move in a northeasterly direction, and, finally, 

 out into the Atlantic. They usually come in the months 

 of July to October, inclusive. 



At the approach of a hurricane or typhoon, the sea and the air are 

 calm, and the barometer falls. Then the wind begins to blow, and 

 clouds and rain come on. The velocity of the wind increases to that 

 of the fiercest gale, or even to that of a tornado. If the center of the 

 hurricane passes over a ship, the sailors notice a sudden change from 

 black darkness and the most violent gale to a dead calm and a clear 

 sky. The barometer will now be very low. The ship is in the ' ' eye " 

 of the storm, an area perhaps 20 miles in diameter. When this has 

 passed, the wind will break forth again, as suddenly as it stopped, but 

 it will be from the opposite direction. Then all the conditions that 

 were noticed when the storm came on will be reversed as the ship 

 passes out of the storm area. 



The damage to shipping and to life because of hurricanes is very 

 great, both in the West Indies and in the southeastern states. It is not 

 only the wind and rain that are so destructive, but also the great 

 storm waves that are raised, and that sweep over all low-lying islands 

 and coasts. 



Typhoons are still more extensive than hurricanes, because they 

 have a greater ocean in which to form and to move. 



280. Weather Service of the United States. The 

 science of the weather is called meteorology (pronounced 

 me-te-or-ol'-o-gy). A Weather Service, or Weather Bu- 



