EXERCISE 17 

 WHAT IS THE RELATION BETWEEN AIR PRESSURE AND WIND? 



Materials. A supply of daily weather maps, usually obtainable in sufficient quantity from the 

 nearest United States Weather Bureau Station. By writing to the Weather Bureau, Washington, D.C., 

 one may obtain a special bulletin entitled " Explanation of the Weather Map." 



Directions. The teacher and students should study together a daily weather map and become 

 familiar with the characters used to represent weather conditions. An explanation of these characters 

 is printed on the map. 



Select a map with a well-defined low-pressure area similar to the maps on page 31 of the 

 " Elements of General Science." Study the wind direction as shown by the arrows around the low- 

 pressure center. How many arrows indicate winds blowing (a) toward a lower pressure ? (6) toward 

 a higher pressure ? (Arrows pointed as .if to cross the isobar toward the lower pressure, though not at 

 right angles, are to be counted in ().) In what percentage of the whole number of cases studied 

 does the wind blow from a high-pressure area to a low-pressure area ? 



What is your answer to the question of this exercise ? 



Additional problems. What conditions of air pressure over the United States would cause a warm wind 

 from the south ? 



By study of weather maps for several successive days, see if you can determine the usual direction and 

 average daily distance traveled by high and low pressures. 



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