HIGH TEAH^ERATURES AND EUCALYPTS 

 • Bv E. N. MuNNS 



I'orcsl U.vamiiici-, [J. S. Par est Service 



Tlic month of June in IDIT was one of the warmest and driest ever 

 experienced in soutiicrn California, ahhoui,di up to that time the year 

 had been cooler than normal. During the winter and spring months 

 certain j)ressurc conditions in the northwest usually cause the frequent 

 and severe windstorms known as "northers" or "Santa Anas." These 

 conditions prevailed in 11M7 from the tenth to the twentieth of June. 

 At different stations in southern California the mean temperatures 

 averaged three to four degrees above the monthly mean ; the maximums 

 were ten to fifteen degrees above the normal and ranged from 100 to 

 121 degrees F. Differing from most of the "northers," the wind move- 

 ment during this period was slight, not exceeding 15 miles an hour. 

 Even this caused great discomfort, for the air was like a draught from 

 a hot oven. It took away the l^reath and scorched the flesh. The shade 

 was almost as unbearable as the sun. Heat prostrations are almost 

 unknown in southern California, but several were recorded during this 

 period. 



Temperatures al)o\c 100 degrees are not unc(jnimon in the valleys of 

 southern California during the months of July, August, and September, 

 but the effect of the temperatures is usually mitigated by cool, refresh- 

 ing nights. During this June wave, however, the minimum tempera- 

 tures were several degrees above the normal. On this account the 

 heat was noticed much more than it would have been under ordinary 

 conditions. The temperatures recorded at different places in the 

 valleys of southern California are given in Tables 1 and 2, the data being 

 taken from published reports of the United States Weather Bureau. 



As none of the co-operative stations of the Weather Bureau are 

 equipped for recording humidity and evaporation, the data taken at 

 the Converse Experiment Station during this period are of interest. 

 Table 3 gives in cubic centimeters the daily evaporation and the rela- 

 tive humidity taken from a sling psychrometer at 6 p. m. daily from 

 the porous-clay cup atmometers, 



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