76 GENERAL SCIENCE 



an inverted cone cloud mass. The funnel shape is due to the rota- 

 tion of the winds around a central point. 



The influence of tornadoes is felt only over limited areas, but the 

 high wind velocity, sometimes exceeding 100 miles an hour, and 

 the extremely low barometric pressures that attend them make 

 them very destructive. 



Why a Kite Remains Up in the Air. A kite remaining high in 

 the air is an example of the pressure of the atmosphere in motion. 

 In flying a kite a boy will run against the wind in order to make 

 enough pressure to force the kite upwar37 since near the earth the 

 trees, buildings and hills interfere with a constant pressure of the 

 atmospheric current in a horizontal direction. After the kite has 

 risen to a height, above the objects which interfere with the wind, 

 it will remain in about the same position. 



Experiment for Studying the Pressure of the Upper Current. Some idea 

 of the pressure of the moving air current may be obtained by flying a kite 

 which has a known number of square feet of surface. Attach a spring balance 

 to the end of the string. Make a series of readings for 10 or 15 minutes, noting 

 whether the pressure of this current remains constant. 



What is the pressure per square foot on the surface of the kite? 



QUESTIONS 



1. Fill a sink or hand basin with water. Place a piece of wood, 

 or any material which will float, on the surface of the water. Pull 

 the stopper. 



Which way does the water run out of the sink or basin? Clock- 

 wise or counter-clockwise? Does it run in the same direction 

 every time you try it? Why does the water take a spiral motion? 

 Which way would the water run out in the southern hemisphere? 



2. If a low is in Iowa, which way will the wind blow in North 

 Dakota, Indiana, Kansas, Wisconsin? 



3. Why is there always a wind near a large fire? 



4. What winds bring rain to your section of the country? 



5. Why do people at the center of a low feel no wind blowing? 



6. Why does the barometer drop as a low approaches? 



7. How are we able to determine whether the low will pass 

 directly over us, south of us, north of us? 



