EXERCISES 257 



283. Exercises. 



1 . Clouds often move in a direction exactly opposite to that of the 

 prevailing wind; what may be the explanation (cf. 274)? 



2. What is a weather vane? Its shape? Why has it this shape? 

 Why does a windmill (cf. 210) often have a vane? 



3. Fishermen on the sea coast often sail out to the fishing grounds 

 at or before daybreak, and return about noon. Do the land and sea 

 breezes help them, or hinder them? 



4. Suppose that a cyclone is 5 miles high, and has a diameter of 

 1.000 miles; how many times its height is its diameter? If, to show 

 these proportions, I make a circle out of wooden boards one inch thick, 

 how many inches in diameter must the circle be? How many feet? 



5. If you were watching a barometer while a thunderstorm was 

 passing, what change in its height would you observe as the center 

 reached you? What would you observe in the case of a tornado? 



6. Would your house be more likely to collapse inward, or outward, 

 if a tornado were to pass near it? 



7. What kind of an air current do you think there is at the "eye" 

 of a hurricane? 



8. In narrow bays a strong wind often " piles up" the water several 

 feet; explain. 



9. Find out, if possible, what are the various flags used as weather 

 signals. 



10. In what ways, in addition to making weather predictions, does 

 the Government seek to prevent loss of life and property at sea and 

 on the lakes? What recent invention has been of great assistance? 



