126 A YEAR IN SCIENCE 



Fog and clouds. Fog and clouds are very much the 

 same. Fog is at or near the surface of the earth, while 

 the clouds are usually half a mile or more above it. In 

 either case, a warm mass of air carrying large quanti- 

 ties of water vapor is cooled. 



Copyright by Henry G. Peabody. 

 FIG. 45. Sunrise above the clouds, Mt. Washington, New Hampshire. 



Rain. If the temperature of air saturated with water 

 vapor is greatly lowered, there will be so much water 

 condensed that it will collect in drops which are too 

 large to float. Kain then takes place, and continues if 

 the condensation continues. 



Snow and hail. Snow is formed in the same way 

 that frost is formed. It forms when the water vapor 

 passes directly into the solid state. Snow crystals are 

 very beautiful and are of many varieties. 



Hail is frozen rain. The rain falls through a layer 



