RELATION OF WINDS 47 
fall decreases. Over the larger part of the arid and 
semiarid sections the sun shines over 70 per cent of 
the time (Fig. 16). 
Winds 
The winds of any locality, owing to their moisture- 
dissipating power, play an important part in the 
success of dry- : 
farming. A per- 
sistent wind will 
offset much of 
the benefit of a 
heavy rainfall 
and careful cul- 
tivation. While 
great general WRN - 
laws have been Fic. 16. Average annual number of hours of 
Porimulated re: sunshine. (Cyclo. Am. Agr.) 
garding the movements of the atmosphere, they are 
of minor value in judging the effect of wind on any 
farming district.. Local observations, however, may 
enable the farmer to estimate the probable effect of 
the winds and thus to formulate proper cultural 
means of protection. In general, those living in a 
district are able to describe it without special obser- 
vations as windy or quiet. In the dry-farm terri- 
tory of the United States the one great region of 
relatively high and persistent winds is the Great 
Plains region east of the Rocky Mountains. “Dry- 
