CLIMATIC CONDITIONS OF THE UNITED STATES. 



313 



period is here well shown. ^ This is the time when summer annuals 

 are active. 



Dalhart, Texas (fig. 6) : This station is characterized by exceedingly 

 high rates for our series of observations — higher rates than were 

 obtained at any other place — in spite of the fact that there was here 

 considerable precipitation throughout the summer. No observation 

 was obtained for the week ending August 3. The maximum weekly 

 rate was 656 c.c. (week ending June 22) and the minimum was 329 

 e.c. (week ending July 20). The march of the index of evaporation 

 intensity suggests a periodicity with a period of several weeks. 



sso 



S2Z 



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00 



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.SI 



5BI 



00 



656^ 



S^ 



£S6 



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Cvnpo/in T/oAf 



SM. 



4; 



S04 



470 



390 



1.64 



329 



diZ; 



Ml 



00 



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LOS 



.00 



461 



4-35t 



447 



,3 S3 



.28 



.70 



.10 



JS 



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4-78 



426 



.19 



OS 





- I B I 



^ 



Fig. 6. — Weekly precipitation and evaporation indices, summer of 1908, Dalhart, Texas. 



St. Louis, Missouri (fig. 7): The maximum weekly rate (212 c.c.) 

 was not attained here until the week ending September 7, and the 

 minimum (71 c.c.) occurred early in the season, for the week ending 

 May 11. The highest rate at this station was but little higher than 

 the lowest encountered at Tucson. There appears to have been a 

 general upward trend of the rate values throughout the whole series, 

 to about September 7. There is here also a suggestion of a periodicity. 

 Rains were frequent and plentiful until the latter part of the series of 

 observations. 



Oxford, Ohio (fig. 8) : Here there was a general increase in evapora- 

 tion intensity throughout the season, until about August 31. The 

 rates vary irregularly, from a minimum of 78 c.c. (week ending May 

 25) to a maximum of 249 c.c. (week ending August 3), the highest ones 

 being nearly as great as those for San Diego. 



^ Livingston 1907, 1. 



