The Regional Adaptation of Corn in Nebraska 13 
The seasonal rainfall and temperature for the years 1915 
and 1916 are also given for the twelve localities in the State 
where corn types were studied in detail during those years. 
REGIONAL TEMPERATURE VARIATIONS WITHIN THE STATE 
Important aspects of temperature related to these studies 
are: (1) mean temperature of the corn growing season, (2) 
duration of the frost- free growing season, and (3) occurrence of 
excessive temperatures of short duration, especially when ac- 
companied by abnormally high wind velocity. 
■1000 3500 3000 Z50G 2000 /500 
3000 2500 2000 J500 -000 
Fig. A — Altitude variation (in feet) in Nebraska. (After Warren.) The south 
to north width of the state is 210 miles, or 3 degrees latitude. The east 
to west length is 425 miles. 
NORMAL MEAN TEMPERATURE 
We are more concerned with the mean temperature of the 
corn growing season than with the mean annual temperature. 
Accordingly, variations thruout the State in the normal mean 
temperature for the period of May to August, inclusive, have 
been compiled and are charted in Figure 3. In response chiefly 
to differences in latitude, this mean seasonal temperature is 
found to decrease approximately four degrees from the southern 
to the northern border of the State. Due to the combined effects 
of increased latitude and altitude, (Figure 4), the corresponding 
mean temperature of extreme western Nebraska is seven degrees 
lov er than for extreme southeastern Nebraska. The altitude rises 
rather continually from 1,000 feet in the southeast to a maximum 
of about 5,300 feet in the west. In general, the isotherms run 
from the northeast to the southwest. 
