Nov., 191S] Recovery of Vegetation at Kodiak 19 



The total precipitation averages approximately sixty inches 

 per annum. Although heavy rains (1.50 inches) are known, 

 the rainfall comes largely in the form of fine mist which, while 

 holding the air at the point of saturation for days together, 

 accumulates very slowly. For this reason, tables of precipita- 

 tion and temperature are apt to give a very incorrect idea of the 

 climate. 



There are about one hundred and sixty days with precipita- 

 tion of one one-hundredth of an inch or more and many more 

 days with low-hanging clouds. The persistent cloudiness 

 greatly cuts down the amount of radiant energy reaching the 

 ground. But the long hours of daylight throughout the growing 

 season, with practically continuous illumination for a month in 

 mid-summer, must largely compensate for the weakness of the 

 light. Measurements of the radiant energy received in this 

 area, if compared with similar measurements in an alpine area 

 of lower latitude such as Pike's Peak, would form an exceedingly 

 interesting and instructive exhibit, for as is well known, the 

 plant societies of the two regions have many resemblances. 

 It was hoped at the beginning of the work that such records 

 could be obtained, but conditions incident to the war made it 

 impossible to procure the necessary instruments. 



EVAPORATION VERY LOW. 



Probably the most significant records available for estimating 

 the conditions under which the plants grow, are those of the 

 hygrothermograph and of the atmometers. The record of the 

 hygrothermograph for a typical week, July 17-24, 1916, is 

 reproduced herewith. In addition, the records of the ten weeks, 

 including the best of the growing season, during which the 

 instrument was operated at Kodiak, may be summarized. 

 During this period temperatures above 70° F. were reached 

 only five times, for an hour or two only in each case. The 

 highest temperature was 73.5°. The lowest was 40°, but 

 temperatures below 45° were reached twenty-six times 

 and sometimes were held for a number of hours. The lowest 

 relative humidity recorded was 47%, and only on fifteen days 

 was the humidity reduced to less than 60%. More significant 

 is the fact that during twelve hundred and sixty hours or 75% 

 of the period, the humidity stood above 80%. Inasmuch as 

 this record was taken in the open in an instrument shelter of 



