59' 



The National Geographic Magazine 



B'rom a photo by Prof. Alexander McAdie 



Ocean Fog Pouring in over the Hills upon San Francisco 



mosphere, which is moving easterlv miles 

 above our heads, and are swept across 

 the continent as an eddy is borne along on 

 a river. The Weather Bureau is learning 

 a great deal about these important upper- 

 air currents by studying the different 



types of clouds, and by noting their alti- 

 tude and rapidity of motion. 



"storm signals of the sky" 



It has been well said that "clouds are 

 the storm signals of the sky." The 



From a photo l)y Prof. Alexander McAdii 



Sea Fog Lifting and Changing to Clouds, San Francisco Bav 



