THE EE1SON WHY. 105 



' Hast thou entered into the treasures of the snow ; or hast thou seen tho 

 treasures of the hail." JOB xxxvin. 



coming, because the mountains are "putting their night-caps 

 on?" 



Because the clouds descend when they are heavy with vapour, 

 and being attracted to the mountain tops they are said to " cap the 

 mountains." 



CHAPTER XXI. 



440. What is snow ? 



Snow is congealed vapour, which would have formed rain ; but, 

 through the coldness of the air, has been frozen in its descent into 

 cry staline forms. (Fig. 1.) 



441. Why is snow white ? 



Because it reflects all the component rays of light. 



442. Why is snow said to be warm, while white garments 

 are worn for coolness ? 



Snow is warm by virtue of its light and woolly texture. But it 

 is also warm on account of its whiteness ; for, had it been black, it 

 would have absorbed the heat of the sun, which would have thawed 

 the snow. Instead of which, it reflects heat ; and the reflected heat 

 falls upon bodies above the snow, while the warmth of the earth 

 is preserved beneath it. Wldte clothing is cool, because it reflects 

 from the body of the wearer the heat of the sun. White snow is 

 warm, because it reflects the sun's heat upon bodies. 



There are few persons but have felt the effect of the sun's rays reflecfedby the 

 white snow on a clear wintry day. And, as regards the warmth of snow 

 towards the earth, by preventing the radiation of heat, it has been found that 

 a thermometer buried four inches deep in snow has shown a temperature of 

 nine degrees higher than at the surface. 



443. Why are lofty mountains always covered with, snow f 

 Because the upper regions of the atmosphere are intensely cold. 



444. Why are the upper regions of the atmosphere intensely 

 cold? 



Because the atmosphere retains but little of the heat of the titn't 

 5* 



