44 



WEATHER AND CLIMATE 



United States on the first weather map in Figure 66. Find 

 the same area on the maps of the next two consecutive days. 



In your notebook 1 complete the following statements and 

 comply with the instructions. 



On the first day the low-pressure area was over the state 

 of On the second day it had moved and was then 



over the state of 



farther _ _ and was over . 



The third day the low had moved 

 _. The kind of weather which 



accompanied this low-pressure area was and , as 



indicated by the markings on the map. 



Study the map (Fig. 73) showing the average paths of 

 high and low pressure areas over the United States and 

 Canada. List in your notebook the conclusions that may 

 reasonably be reached on the basis of the data shown. 



OTHER INVESTIGATIONS WHICH YOU CAN MAKE 



1. How can a wind .vane be made? 



2. How can a weather map be made? (See Barber, 

 First Course in General Science.) 



3. Make an investigation of the various types of cloud 

 forms and observe them from day to day. 



READINGS WHICH WILL HELP ANSWER THE 

 PROBLEM QUESTIONS 



What is the weather lore of your locality? Every 

 community has its weather prophet. He is supposed 

 to be able to tell in advance whether the next winter 

 is to be cold or mild, long or short, and whether the 

 summer will be dry or wet. Many people still believe 



1 See workbook, p. 19. 



in signs and omens and will plant certain crops only 

 when the moon is new or in a particular phase. There 

 is hardly a hamlet in the world where weather pre- 

 diction by signs is not engaged in. In fact, so common 

 is the practice and so long has it gone on that many 

 weather signs have been made into little rimes so 

 that they may be more easily remembered. These are 

 called weather lore. 



There is little or no scientific basis for believing the 

 long distance weather telling of local prophets and 

 much of the weather lore. There are, however, some 

 weather sayings which have grown up as a result of 

 a long period of observation and which are fairly good 

 indicators of the weather. In fact, some of these have 

 a certain amount of scientific foundation which, of 

 course, is unknown to most of the users. Study all the 

 weather lore available and try to find sayings which 

 may have some scientific foundation. 



How are thermometers used in foretelling weather? 

 In the study of the topic about winds you learned 

 that the movement of great air masses over the earth 

 was caused by the difference in heating of various 

 parts of its surface. Thus, the temperature of the air 

 at two places, taken at the same time, will give a 

 clear idea of the movement and currents of air mass- 

 es. Also, in the study of a previous topic you learned 

 that the water-holding capacity of the air is influenced 



' v N. r ' 



I | \ s___Lr -C ' 



FIG. 73. USUAL PATHWAYS OF HIGH AND LOW PRESSURE AREAS 



The heavy lines indicate "highs" and the lighter lines indicate "lows." 



