184 GENERAL SCIENCE 



week or even more. It should be noted, however, that the 

 forecasts are made for large areas and not likely to prove 

 correct in every detail for every locality. The movement 

 of areas of low and high pressure in the belt of prevailing 

 westerlies can only be estimated. Sometimes they in- 

 crease in speed and sometimes decrease. 



The information given out by the Weather Bureau is 

 of great value to farmers, those interested in shipping, in 

 fact all those whose business or pleasure in any degree 

 depends upon the weather. The farmer may be able to 

 save his grain by having knowledge of an approaching 

 storm or his crop of peaches by learning of a coming frost. 

 Hurricanes and other storms often do much damage to 

 shipping and would do much more if it were not for 

 advance information which enables ships to move out of 

 the path of the storm to seek some safe harbor. News of 

 a cold wave enables railroad companies and commission 

 merchants to save their patrons a great deal, since many 

 articles of food such as fruit and vegetables are spoiled by 

 freezing and cannot be shipped without danger of loss in 

 cold weather. Flood warnings are also the means of 

 saving much property along the larger rivers. 



It can usually be arranged to have several copies of the 

 weather maps sent to the school by applying to the nearest 

 Weather Bureau office and giving assurance that the maps 

 will be properly used. 



QUESTIONS 



1. Why does low barometer usually indicate the approach 

 of a storm? 



2. How does air distribute heat? 



3. Why do balloons float lower at night than in the daytime? 



4. Why does -a rise in temperature usually follow the begin- 

 ning of a snowstorm ? 



