80 
Rene arch Bulletin Xo. 5 
CLIMATIC CONDITIONS. 
In order that the data offered in this bulletin may be more 
clearly understood, we are giving several tables to show the 
climatic conditions under which this work was done. Figure 2 
and Table 32 give annual precipitations and show years of high 
and years of low rainfall. Other tables give the average daily 
temperature, wind velocity, and rate of evaporation from a free- 
water surface for certain months for the years 1908 to 1912. 
These averages show almost as wide variation as the rainfall. 
The averages are, however, not so important as the extremes. 
For example, in Table 37, June, 1911, shows an average wind 
velocity of 10.5 miles per hour. Tn that month the daily average 
for the four days, 12th to loth, was about fifteen miles an hour. 
There were hours within these days when the wind velocity was 
much higher than others. It is the extreme conditions that are 
critical. Those four days would do much more damage to the 
crop than many days of less wind. The extreme wind velocity 
within these days was doubtless much more damaging than the 
average. Another example is in Table 36. The highest average 
monthly evaporation given is for June, 1911. The four days, 
12th to loth, which showed such a high wind velocity, also show 
a high evaporation. Such days as these are what we call extreme 
conditions. We will not attempt to give a discussion of the 
climatic conditions, but a study of the several tables offered will 
show more clearly why some of the results were obtained. 
