12 BULLETIN 698, U. S. DEPARTMENT OF AGRICULTURE. 
LOCAL VARIATION IN PRECIPITATION. 
Much of the summer rainfall is derived from storms which are very 
local in extent. In a single storm period a series of heavy showers 
may occur at about the same time in the same district but covering 
different localities and leaving intervening stretches almost unwatered. 
The variation in the rainfall at two near-by points is illustrated in 
Table III. This table compares the rainfall measured at the United 
States Weather Bureau observatory in the town of Amarillo with 
that recorded at the Amarillo Cereal Field Station during seven sum- 
mer months in the years 1909 and 1914. The distance between the 
two points of observation is about 24 miles. 
Tasie III.—Comparison of the rai nfall, in inches, at the United States Weather Bureau 
observatory and at the Amarillo Cereal Field Station during the seven months from 
March to September, inclusive, in 1909 and 1914. + 
Station. | Mar. | Apr. | May. | June. | July. Aug. | Sept. | Total. 
. | : 
Season of 1909: | 
United States Weather Bureau........--_- |} 1.28} 0.50]-1.08 | 4.72] 3.63) 0.87 2.19 | 14.27 
Cereal field station...............-....... | 1.08] .27] 1.13] 5.90| 219| 1.39] 1.90| 13.86 
Season of 1914: | 
United States Weather Bureau......_..-- 5 -95 | 4.43 384) 3507) 297] 200 1 ass 
Cereal ficidis tations e+e, See el a |} -02) 1.27) 3.8 65715 90a e252 41:10°} ft 29 
| 
These local rains frequently last but a short time, but are of a 
torrential nature. This often results in a loss of much water by run- 
off. Such beating rains also puddle the surface soil and cause much 
damage in that way. 
Humoiry. : 
The atmospheric humidity is low, on the average. This no doubt 
plays an important part in influencing transpiration from growing 
crops. 
WIND. 
Monthly data on wind are shown with other climatic data in Table 
IV. The average hourly wind velocity in the 10 years from 1907 to 
1916, inclusive, is 11.8 miles. During the 4-year period from 1907 
to 1910, inclusive, there was an average of 14 days in each year in 
which a wind velocity of over 40 miles an hour was recorded. The 
maximum, 63 miles, occurred on March 24, 1909. During the 6-year 
period from 1911 to 1916, inclusive, the data show merely the max- 
imum hourly velocity recorded during the month and no longer the 
number of days having high wind velocities. The maximum, 46 
miles an hour, occurred in February and April, 1911, and in April, 
1915. Such high winds often cause great damage to the crops 
either by covering up the young plants, by cutting them off by moving 
particles of soil, or by blowimg down the crop when it is almost or 
quite mature. 
