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THE POPULAR SCIENCE MONTHLY. 



meets with the cold current from the north, it slopes upward over the 

 cooler current, and forms stripes or bands of stratus clouds along the 

 horizon, as shown in Fig. 3. 



Fio. 2. Cumulus Clouds. 



These stratus clouds indicate to the observer the fact that a warm 

 current is coming northward. 



When in summer a cool current is moving southward, it encoun- 

 ters the warm equatorial or tropical current, which again glides up- 

 ward and over it, and forms horizontal bands of stratus clouds along 

 the upper line of contact, as in winter storms ; but, in addition, the 

 denser cold air from the north, moving with more momentum, will 

 lift up the warm and saturated air from the tropics, and its moisture 



