Relative Humidity 



Trends in relative humidity over the growing season were not pronounced. Minimum 

 humidity generally was highest in raid-June and lowest in July and August (fig. 8). 

 Humidity readings for the same time periods varied considerably between years. The 

 yearly variations of minimum humidity were greatest early and late in the season, 

 corresponding to periods of generally unstable weather. During the moist June period, 

 weekly averages of minimum humidity were sometimes greater than 50 percent. Even dur- 

 ing the driest part of the summer, weekly averages seldom dropped below 15 percent. 

 Monthly averages of maximum and minimum relative humidity over the 5-year period are 

 given in table 9. 



Maximum and minimum humidities remained within 5 percentage units of their daily 

 extremes an average of about 4.5 hours. Maximum and minimum readings were of about 

 the same duration until July and August [table 10). During these 2 months, minimum 

 humidity usually lasted longer than maximum. 



Minimum relative humidity averaged less than 2 percent lower on southwest expo- 

 sures than on northeast exposures. Differences attributable to elevation were some- 

 what greater. Stations at 7,100 feet were 2.9 percent (a = 2.8) lower on southwest 

 exposures, and 3.8 percent (a = 3.2) lower on northeast exposures than the stations 

 at 8,200 feet. 



100 



MAY 



JUNE 



JULY 



AUG 



SEPT 



OCT 



Figure 8. — Relative humidity at the station on the southuest exposure at 

 7,100 feet elevation: weekly means of daily maximum and of daily 

 minimum humidity ; averages and range of means over the 5-year period. 



16 



