VAPORIZATION. 129 



Q. Are ALL clouds ALIKE ? 

 A. No. They vary greatly in density, 

 height, and colour. 



Q. What is the chief CAUSE of fog and 



CLOUDS ? 



A. The changes of the wind, 



Q. How can the CHANGES of the WIND affect 

 the CLOUDS? 



A. If a cold current of wind blows 

 suddenly over any region, it condenses 

 the invisible vapour of the air into 

 cloud or rain : but if a warm current 

 of wind, blows over any region, it 

 disperses the clouds, by absorbing their 

 vapour. 



Q. What COUNTRIES are the MOST CLOUDY? 



A. Those where the winds are most 

 variable, as Britain. 



Q. What COUNTRIES are the LEAST cloudy ? 



A. Those where the winds are not 

 variable, as Egypt. 



Q. What DISTANCE are the CLOUDS from the 



EARTH ? 



A. Some thin light clouds are elevated 

 above the highest mountain-top; some 

 heavy ones touch the steeples, trees, and 



