A/ORTH POLE 





""^^^.. 

 ."-. 



EQUATOR 



Diagram showing concentration of convection in the vicinity of the 

 Equator, north winds near the ground and south winds aloft, which 

 would occur on a non-rotating earth if the sun's heat were applied 

 mainly in low latitudes, as it actually is on the rotating earth. 



effects pulling the northgoing winds to the east and the 

 southgoing winds to the west. If this were all, then the river 

 of air would become a simple flow of west winds aloft and 

 east winds below, with the entire air mass slowly drifting 

 toward the pole at high altitudes and returning toward the 

 equator along the ground. But as the high winds travel north 

 from the tropics the air cools, and as it sinks to the ground 

 in the Horse Latitudes of about 30° N. it spreads out partly 

 toward the pole and partly southward. Still blowing from the 

 west, the poleward branch meets cold east winds moving 

 across the ground from the Arctic, and here in a latitude of 

 about 60° N. it is forced to ride over the heavier air and con- 



