4 BULLETIN 219, U. S. DEPARTMENT OF AGRICULTURE. 
The altitudes vary from approximately 1,400 feet in the north 
to 6,000 feet at Cheyenne, Wyo. The southern portion of the terri- 
tory has a higher average altitude, a higher average rainfall, and a 
correspondingly higher rate of evaporation than the northern portion. 
CLIMATIC CONDITIONS. 
The climate of the Great Plains has been classified as semiarid. 
It may be better to say that it is changeable, varying from season 
to season from almost humid conditions to almost arid, with a mean 
annual precipitation relatively low. Years of relatively high pre- 
cipitation may be followed by years of relatively low precipitation. 
Other climatic factors usually correspond with the rainfall. A 
year of relatively high rainfall will have a lower rate of evaporation, 
higher humidity, and lower wind velocity than will be found in the 
unfavorable years. 
Another climatic factor of much importance in crop production 
in the Great Plains is the distribution of the rainfall. A relatively 
low rainfall, property distributed, may produce a crop where a 
much higher rainfall, coming with unfavorable distribution, may 
result in a crop .failure. 
No attempt will be made in this bulletin to give a full description 
or record of the climatic conditions at the various stations during 
the time covered by these investigations. 
Table I gives the maximum, mmimum, and average annual and 
seasonal precipitation and seasonal evaporation at each station for 
the years for which experimental work is here reported. By seasonal 
is meant the period between the average time of seeding and the 
average time of harvesting. 
Table I. — Annual and seasonal precipitation and seasonal evaporation at fourteen 
stations in the Great Plains area. 1 
Alti- 
tude 
(feet).* 
Precipitation (inches). 3 
Seasoi 
lal evaporation 
Station. 
Annual. 
Seasonal 
(inches). 3 
Mini- 
mum. 
Maxi- 
mum. 
Aver- 
age. 
Mini- 
mum. 
Maxi- 
mum. 
Aver- 
age. 
Mini- 
mum. 
Maxi- 
mum. 
Aver- 
age. 
Judith Basin 
Huntley 
4, 228 
3,000 
1,875 
2,543 
1,468 
2,253 
2,950 
3,950 
3,000 
4,600 
2,050 
2,900 
4,000 
3,676 
14.96 
11.92 
10.28 
11.93 
11.94 
12.72 
6.64 
13.77 
11.18 
14.51 
15. 59 
11.82 
13.69 
10.69 
23. 78 
11.92 
18.99 
21.22 
21.95 
15.68 
17.73 
18.51 
23.01 
22.46 
27.80 
23.58 
16.35 
27.80 
18.06 
11.92 
14.84 
16.69 
16.71 
14.20 
13.11 
16.14 
18.05 
18.28 
21.30 
18.54 
15. 11 
18.28 
7.04 
5.92 
4.75 
6.85 
7.85 
8.92 
4.08 
2.53 
6.85 
6.42 
8.18 
2.79 
5.09 
6.17 
17.21 
6.02 
14.49 
16.28 
14.98 
12. 47 
9.78 
8.52 
12.66 
13.86 
17.97 
14.43 
9.85 
11.38 
9.34 
5.97 
9.66 
9.79 
10.11 
10.36 
6.90 
4.69 
9.45 
9.02 
11.17 
8.65 
8.01 
9.13 
22. 012 
23. 754 
20. 422 
20. 673 
18. 663 
21.539 
26. 472 
23.804 
28. 445 
26.064 
30. 625 
34. 325 
35. 459 
33. 804 
29.353 
24.214 
26. 877 
25. 745 
24. 893 
28. 239 
33. 750 
29. 381 
38. 168 
35.654 
44.373 
43.510 
41.748 
42. 076 
24. 491 
23.984 
Williston 
24. 216 
"Diclrinsmi , . 
23. 919 
Edseley 
21.866 
Hettinger 
24. 639 
Belle Fourche 
Scottsbluff 
28. 794 
26. 081 
North Platte 
Akron 
32.353 
31. 420 
35. 790 
Garden City 
Dalhart...*. 
38.185 
38.988 
36. 724 
i The years covered are the same as for the data shown in the other tables for the several stations. 
- The altitude given is for the field where the work was done and is based in most cases on that of the 
nearest town. 
3 The records of annual precipitation for 1914 are not included. The records of seasonal precipitation 
and evaporation for 1914 are included for all stations, being figured from May 1 to Sept. 1. Evap- 
oration measurements are made from a free water surface, in a tank sunk into the soil to almost its full 
depth. The water surface is kept about level with the surface of the ground. 
