10 



FIELD OPERATIONS OF THE BUREAU OF SOILS, 1910. 



showers or rains extending over several days, A great variation is 

 noted in the rainfall shown by calendar years. The records as kept 

 for seasonal precipitations commencing with September do not show 

 such a wide range, for the greatest rainfall of the season may occur 

 either before or after the end of the calendar year. The following 

 table shows the seasonal precipitation at Red Bluif from 1877-78 

 to 1909-10 : 



Scasonohlc ijrccipitulion nt Red /Huff, coiii»iriiciii(/ irith t<rpte>nber. 



INfaxiniuni precipitations have occurred as follows: At Red Bluif, 

 49.01 and 40.37 inches for the calendar years of 1878 and 190(5, re- 

 spectively; at Corning, 34 inches in 1890; at Chico, 36.24 inches in 

 1892. Minimum precipitations occurred as follows: At Red Bluff, 

 12.91 inches in 1898; at Corning, 7.58 inches in 1898; at Chico, 12.31 

 inches also in 1898. The average annual rainfall for Sacramento 

 covering a period of 51 years is 19.41 inches. 



In the Red BluH' area the general movement of air is from the north 

 and northeast into the valley. During the summer months there is 

 normally a marked movement of air from the south. " Northers," as 

 they arc called, .sometimes occur. They are hot, dust-laden north 

 Avinds, occurring most frequently during May, June, and Jul}". Some 

 damage is frequently done to the fruits and growing crops during 

 their passage, their liot. withering character extracting much water 

 from the soil and \cgetation. 



Alternating periods of rainy weather and sunshine occur in the 

 rainy .scjison, but the summer months are very bright and clear, clouds 

 being rarely seen. At Red Blulf from the year 1877 to 1909 the clear 

 days average 210, i)artly cloudy 77, and cloudy 72 per year. The 

 average numi)er of foggy days at the same place for the same period 

 was 9 per year. An average of 2 hail storms and 4 thunderstorms 

 occur during each year. Snow in quantities is a rather rare occur- 

 rence, l>iit in Jiimiary. 1907, Red Bluff received 14 inches. Light 

 frosts and films of ice appear during the winter months. At Red 



