SUNLIGHT 11 



the motion <»f its motecnlei Incomes faster. Soon the. 

 begins to bubble and boil from the rapid motion 

 of it- molecules. Some of the surface molecules from 

 rapid motion are thrown off from the boiling water 

 and float about in the air in the form of a gas, which is 

 called sti:\m. 



4. Condensation. — If, in fee steam from a boiling 

 kettle, I object is held for a few moments drops 

 of water coll. it on it. The betted molecules which make 

 up the steam strike against the cold object and are 

 cooled off, become quiet, and collect in drops of water. 



-team is said to-coNDRNSE. When steam rises 

 from boiling water into the air above, it cools off and 

 gathers into fine drops of moisture, which make up the 

 white steam to he Been rising from hot water. Notice 

 how dense and white the Bteam is on a cold day. 



5. Evaporation. — Winn heat waves from the sun 

 strike against tfcodiea of water, such as oceans, lakes and 



, they cause rapid motion among the surface mole- 

 cules of water; this motion is so strong at times that 

 many of the water molecnlei are thrown off into the 

 air above as tl from the kettle of boiling water. 



This change is called i:v adoration. But evaporation 

 is not dependent on sunshine, though it takes place 

 more rapidly under its influence. Air has the power of 

 taking Up water like a sponge, and like the sponge can 

 hold only a certain amount. When air has taken up all 

 the wal n hold, it hi said to be saturatkd. Then 



evaporation ceases, but so long as the air is not satu- 

 rated evaporation may go on. A bucket of water placed 

 in a room protected from sunshine gradually evapo- 



