Farm Types in Nebraska 21 
Mg. 8. — ;A cross-sectional view of annual cropping along a line extending 
from southern Arkansas to the extreme northern part of Michigan. (See key 
map placed on the right-hand side of the graph.) 
mally received during the year. To reduce the quantity of 
heat from degrees to per cent, 450 month-degrees above freez- 
ing was used as a base. This quantity of heat is found in only 
the warmest parts of the United States. 
MONTH-DEGREES ABOVE FREEZING 
Figure 11 will show where this quantity of heat (450 
month-degrees above freezing) is found in southern Texas. 
To calculate a similar figure for any given Weather Bureau 
station, it is only necessary to determine the total of the 
normal mean temperature of the months above freezing and 
subtract from the sum as many thirty-twos as there are 
months having a normal mean temperature above freezing.* 
This gives what is spoken of here as month-degrees above 
freezing or, in brief, simply month-degrees. Thirty-two de- 
grees is used as the lower limit because it marks a point below 
♦Sample problem: — Calculation of the month-degrees at the University Farm, 
Lincoln, Nebraska. 
Normal mean temperature: Jan.. 24.9; Feb., 25. 3: March, 41.6; April, 52.7; 
Mav, 62.3; June, 71.1: July, 76.0; August, 75.0; Sept.. 67.4; Oct., 55.0; Nov. 40.6; 
Dec., 28.1. 
(41.6-|-52.7 4-62.3-1-71 .1 -j-76.0-|_' 75.0-J-67.4 +55.0 _|_ 40.6) — (0x32) == 
month-degrees above freezing. 
253.7 
