62 



GENERAL SCIENCE 



v. 



Winds. Make a small pin- wheel and hold it over a Bunsen 

 burner or a kerosene lamp, high enough so it will not burn. 



The rising air currents will 

 cause the pin-wheel to turn. 

 The heated air may be ob- 

 I served rising if the light is be- 

 Je tween you and the window, 

 t Often, heated air may be dis- 

 I /cerned rising over radiators 

 ^S and stoves. If the lamp is 

 Wery large, smoke from a joss 



stick held on the side near 

 FIG. 53a. Origin of winds. Why does the air , , ... , , 



at 6, 6 rise? Why does the air at e, e fall? Why the bottom Will show that 

 does the air at c,c move toward the heated area? c ld air is rushing in and 



pushing the heated air up. 



As_ this heated air rises it takes a counter clockwise spiral form 

 much like the way we see water running out of a sink at home. 



If you could see the air as you can see water it would seem 

 like the Whirlpool Rapids of 

 Niagara all swirls, pockets, 

 vortexes and curling eddies. 

 The inclined rock bottom of 

 the Niagara below the falls 

 makes the Whirlpool Rapids 

 what they are. But the vor- 

 texes and currents of the air 

 are due to the constant efforts 

 of the atmosphere to find its 

 temperature level. 



Lows and Cyclones. Sup- 

 pose the barometer reads lower v 

 in Indiana than in any of the 

 surrounding states. Naturally, 

 air from the northern, southern, 

 eastern and western parts of 

 the country would rush in, pushing the lighter air over Indiana up- 

 ward. Even a small difference in the reading of the barometer would 



. ORTHERN . HE 



FIG. 536. Cause of the rotation of the 

 wind. 



