106 THE EEASON WHY. 



" He causeth the vapours to ascend from the ends of the earth : he maketh 

 lightnings for the rain : he bringeth the wind out of his treasuries." Ps. xxxv. 



rays as they pass to the earth. Because at high altitudes the air 

 is greatly rarefied. And because the radiation of heat from the 

 earth does not materially affect such high regions. 



445. What is meant ty the snow line ? 



The snow line is the estimated altitude in all countries where 

 snow would be formed. Even at the equator, at an altitude of 

 15,000 to 16,000 feet from the level of the sea, snow is found upon 

 the mountain summits, where it perpetually lies. As we proceed 

 north or south from the equator the snow line lessens in altitude. 

 Had we in England a mountain 6,000 feet high, it would be per- 

 petually crowned with snoio. 



446. Why do we near of red snow ? 



Red snow is the name given to the snow in the arctic regions 

 upon which a minute vegetable (probably the Protoccus nivalis) 

 grows, imparting to the snow a red colour. Recent microscopic 

 investigations have shown it to consist of a minute vegetable cell, 

 which secretes a red colouring matter. 



Snow is found to be of greater import nee to man than is generally supposed. 

 But, although in this country we. are enabled to recognise the hand of Provi- 

 dence in the gift, there are latitudes wherein the blessing thus conferred is 

 more deeply felt. In such countries as Canada, Sweden, and Russia, the falling 

 of snow is looked for with glad anticipations, quite equalling those which 

 herald the " harvest-home" of England, or the " vintage" of France. No sooner 

 is the ground covered with snow, than cranky old vehicles that had been jolting 

 over rough roads, and sticking fast in deep ruts of mud, are wheeled aside, and 

 swift sledges take their place. Towns distant from each other find an easy 

 mode of communication ; the markets are enlivened* and trade thrives. Snow 

 supplies a kind of railroad, covering the entire face of the country, and sledges 

 glide over it, almost with the speed of the locomotive. 



447. What is sleet? 



Sleet is snow which, in falling, has met with a warmer current of 

 air than that in which it congealed. It therefore partially melts 

 and forms a kind of wet snow. 



448. What is hail ? 



Hail is also the frozen moisture of the clouds. It is probably 

 formed by rain drops in their dpscent to the earth, meeting with an 

 exceedingly cold current of ait by which they become suddenly 

 frozen into hard masses. 



