94 



THE EEASON WHY. 



'Behold, he withholdeth the waters, and they dry up; also he sendeth them 

 out, and they overturn the earth." JOB xn. 



381. What are the dimensions of clouds ? 



A single cloud has been estimated to have as many as twenty 

 square miles of surface, and to be above a mile in thickness, while 

 others are no larger than a house, or a man's hand. 



Fig. 7. CUMULUS, OE PILE CLOUD. 



. 382. Sow are clouds affected ly winds ? 



If cold winds blow upon the clouds, the cold condenses the vapour, 

 turning the clouds into rain. But if warm dry winds blow upon 

 the clouds, they rarefy the vapour to a ^j^ater degree, and 

 temporarily disperse the clouds. 



383. Sow do ivinds affect the shapes of clouds ? 



When winds are mild and gentle, the clouds break into small 

 patches, and rise to a considerable height. But when the winds are 

 cold and blustering, the clouds fly low, and roll along in heavy 

 masses. 



384. Why are east winds usually dry ? 



Because in coming towards England they pass over vast continents 

 of land, and comparatively little ocean. Hence they are not loaded 

 with vapours. 



385. Why do west winds generally bring rain ? 



Because they come across the Atlantic, and are heavily charged 

 with vapour. 



386. Why are north winds generally cold and dry ? 

 Because they come from the arctic ocean, over vast areas of ice 



and snow. 



