MOISTURE IN THE AIR 111 



3. Why does no frost form on the outside of window panes in cold 

 weather? 



4. How can you tell, by consulting the wet- and dry-bulb ther- 

 mometers, whether the dew-point at the time is high or low? 



6. Examine the wet- and dry-bulb thermometers in your school and 

 see if the relative humidity is sufficiently high. If the school has no 

 wet-bulb thermometer one can easily be made from an ordinary 

 thermometer. 



6. Why is it incorrect to say that dew falls? 



7. If the dew-point is above 40F. on autumn evenings no frost is 

 expected. How does the formation of dew prevent frost? 



8. When you notice single clouds near the horizon on a warm day 

 you find that the under side is nearly level. How do you account for 

 this? 



9. Explain how high mountains prevent moisture-bearing winds from 

 carrying moisture beyond them (63, 93). 



10. From a geography, select and name a desert that is due to the 

 cause mentioned in question 9. 



11. Clouds, being composed of particles of liquid water, are heavier 

 than air. Why then do they not descend to the earth? 



12. If a wind moves from a cold region into a warmer one, will its 

 capacity for moisture be increased or diminished? 



13. Will it be likely to bring clear or cloudy weather? Why? 



14. What wind ought to bring clouds in your region? 



