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pointing eastwards. As the upper wind increases 

 in strength it gradually draws the lower current 

 with it, and so the air below is mixed with the 

 atmosphere above. Thus the light mists formed 

 by slight cooling during the night are carried up 

 into the upper regions. 



Hence the mounting up of the morning mist, 

 especially when the barometer falls at the same 

 time, is rightly considered as foreboding rainy 

 weather. 



The Clouds are masses of mist in the upper air ; 

 they arise from the cooling of the higher layers of 

 the atmosphere when fully charged with moisture, 

 as mists and fogs are caused by chilling influences 

 at the surface. Clouds are formed by the mixture 

 of the moist air from the south with the cold cur- 

 rents from the north, just as the breath from our 

 lungs becomes visible with mist in cold weather. 



If, being on a mountain while it is raining, you 

 enter the region of clouds, you will find yourself 

 suddenly surrounded with thick masses of fog, and 

 will perceive the fine droplets of the falling mists. 

 But these little drops become larger as they fall ; 

 for, just as happens when any other cold body is 

 plunged into moist air, the water is thrown down 

 upon their surfaces, while they sink down through 

 the lower warmer and vapour-charged layers of 

 the atmosphere. The rain, therefore, which comes 

 down to the earth is derived not only from the 



