THE UNITED STATES WEATHER BUREAU 



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4, high, swaying whole trees, blowing up twigs from the ground ; 



5, gale, breaking small branches, blowing loose bricks from chim- 

 neys ; 6, hurricane or tornado, destroying everything in its path. 



2. It may be well to have the class divided into sections and 

 allow each section to keep the records for a certain time, so that 

 all together -may keep the record for a large part of the school year. 



3. After the records have been kept for a month or longer study 

 them to see if you find any relation between (a) pressure and tem- 

 perature, (b) pressure and precipitation, (c) pressure and direction 

 of wind, (d) pressure and cloudiness, (e) precipitation and direction 

 of winds, (/) temperature and direction of winds. 



LABORATORY EXERCISE 39 



Purpose. To learn how one may foretell the weather by a 

 study of weather maps. 



Materials. Series of consecutive weather maps. 



Directions, i. Find each of the following on the map and 

 explain what it signifies : (a) the continuous black lines ; (6) the 



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