292 



THE SEASONS CLIMATE AND HEALTH 



Review the study of the effects of the sun's altitude and length of 

 day upon the temperature (Arts. 307 and 308) and explain why 

 January should cause a wider range of temperature than does July. 



Does New Orleans, La., or Grand Forks, N. D., have the greater 

 variation in temperature between summer and winter? Why should 

 this be so? 



Why should the 70 isotherm bend so far south during July in 

 Colorado and New Mexico? Trace the 70 isotherm throughout its 

 length explaining all the bends in it. Remember that the principal 

 factors in determining temperature are: (1) Altitude of the sun; (2) 



' Lonaitudp West io from 6 



FIG. 218. Average temperature for July, 25 years. 



length of day; (3) prevailing wind direction; (4) proximity to bodies 

 of water; (5) presence of mountain ranges. 



What portions of the United States are so situated that the climate, 

 especially the temperature, is largely determined by the ocean? (Re- 

 call the most frequent paths of LOWS and HIGHS across the United 

 States.) Account in part, at least, for the temperature along the 

 coast of California? 



After studying the July and the January maps, state whether the 

 Atlantic or the Pacific Ocean has the greater effect upon the nearby 

 portions of the United States. Why should this be so? 



In studying such maps as these, we must learn to estimate the 



