ORCHARD LOCATIONS AND SITES 



645 



to elevation are shown in Fig. 68. These graphs represent temperature 

 variations on comparatively still, clear nights at stations in a mountain 

 valley during the blossoming period of fruits. Though the minimum 

 temperature was not invariably recorded at the lowest elevations, on 

 each of the four nights when there was danger from frost the higher 



55 



S 40 



20 



1914- f '^^ 

 April 



12 13 14 



ZQ 21 « 24 25 26 27 



16 n 

 May 



Fig. 68. — The daily minimum temperatures for stations of different elevations extend- 

 ing from the high agricultural land to the lowest agricultural land of the valley. {After 

 Batchelor and West^} 



elevations registered temperatures above the probable danger point 

 and a fruit crop on the lower levels probably would have been destroyed. 

 "The minimum temperatures experienced by the bench lands and upper 

 slopes of the tillable area in a mountain valley average from 6 to 10°F. 

 warmer than the valley bottoms due to the drainage of cold air to the 

 low areas during the typical clear, calm, frosty nights. "^ On calm but 

 cloudy nights the variation in minimum temperatures between high 

 and low points in this valley is reduced to about 40 per cent, of that 

 on calm, clear nights and during windy weather there is very little differ- 

 ence in their minimum temperatures. 



