428 ] Understanding the Weather 



How Air Currents Affect Rain: When the raindrops are formed in 

 gently rising air, the condensation takes place very slowly and quite 

 small drops may fall in a drizzle. But when the drops are formed 

 in powerful upward currents, the drops may be held aloft until 

 they are very large (to a fifth of an inch in diameter). This kind 

 may fall with great splashes the kind you often see just before 

 a thunderstorm downpour. At times the larger raindrops flatten 

 out and split up as they fall. 



Sun Showers: Occasionally we have the odd effect of rain falling 

 from a clear sky overhead. This may be due to the drops being 

 delayed in their fall by rising air currents or by friction with the 

 air. Thus before the drops reach us the clouds from which they 

 started have blown away or evaporated. 



Another curious sight is rain falling on one side of a street 

 while the other remains dry. This is simply caused by small clouds 

 meeting with a cold air current that turns their vapor into rain- 

 drops which fall only over the area the clouds had covered. 



A child may think of rain as blowing to his neighborhood from 

 great distances possible from over the ocean. This is never the 

 case: Rain falls where it forms. The moisture may have been ab- 

 sorbed into the air many miles away, but it is never blown to us as 

 "ready-made" rain. 



Billions of Snowflakes, No Two Alike 



Probably no other event in nature is so thrilling to children in 

 our latitudes as the first snowfall of the season. It is as if snow were 

 a substance designed to turn the humdrum world into a dazzling 

 fairyland. Observation only strengthens the fairyland illusion, for 

 if a youngster studies a flake through a magnifying lens, he notes 

 that each snow crystal has a lovely, delicate design, as if woven 

 on a fairy loom. 



Though billions of snowflakes may fall, no two are exactly alike 

 in design, except that each one is six-sided. Some flakes, as you 

 can see with a magnifying glass, are more solid than others. They 

 are formed in clouds very high above the earth. The most beauti- 



