These comparisons illustrate the error possible in attempting to project data 

 even on averages obtained from nearby valley stations to mountain slopes. Depending 

 on which of the two valley stations is used, the adjustment for maximum temperatures 

 would be a 4.7° F. or 6.3° F. decrease per 1,000-foot rise and for minimum temperatures 

 a 1.2° F. or 2.4° F. decrease per 1,000-foot rise. This compares favorably to the 

 average differences of 5.4° F. for maximum and 2.5° F. for minimum temperature decrease 

 per 1,000-foot elevation rise measured on the mountain grasslands themselves. However, 

 the projection of precipitation data is subject to much greater error; depending upon 

 the valley station selected, the adjustment would be a decrease of 0.24 inch/month per 

 1,000-foot rise or an increase of 0.12 inch/month per 1,000-foot rise in elevation. 

 The precipitation difference resulting from elevational differences between the 

 mountain grassland stations amounted to an increase of 0.42 inch/month per 1,000-foot 

 rise in elevation. 



Table 13 . --Average weather differences between the 7 ,100 -foot station on the southwest 

 exposicre and records'^ obtained at Virginia City, Mont., and Ennis, Mont. 



VIRGINIA CITY • ENNIS 



' (5,835-foot elevation) • (4)955-foot elevation) 







Differ from 



7 , 100-foot station by: 



TEMPERATURE (°F.) 





(a) 





Mean monthly maximum 



8, 



,1 (1.6) 



10.4 (1.7) 



Absolute monthly maximum 



7. 



.8 (2.3) 



10.6 (2.3) 



Mean monthly minimum 



3, 



.3 (3.6) 



2.2 (4.7) 



Absolute monthly minimum 



2, 



,8 (3.7) 



2.7 (2.9) 



PRECIPITATION 









(Inches/Month) 



0, 



.31 (0.76) 



-0.25 (0.77) 



U.S. Dep. Commerce, Weather Bureau climatological data, monthly summaries. 



24 



