512 



Bulletin 316 



is considerably above the freezing point during the period of spring frosts, 

 it tends to hold the temperature of the air over adjacent lands, particularly 

 at night, above the point of danger. In the fall the water gives off the 

 large quantities of heat stored up diu-ing the warm summer months and 

 thus wards off frosts. 



For these reasons, a location near a large body of water enjoys an 

 immunity from frost not found in inland localities. Reference to the 

 accompanying charts of the last killing frost in spring and the first in fall 



Fig. 138. — Average nutnher of days between the last frost in spring and the first in fall 



vvdll make this clear. In New York the prevailing winds are from a west- 

 erly direction, and for this reason the east side of a body of water is 

 considered most favorable so far as freedom from frosts is concerned. 

 The influence of a body of water also extends farthest on its east side, the 

 distance depending mainly on the size of the body of water and on the 

 slope of the land. The distance is greater for large bodies of water and 

 for land that slopes gently away from the water. For example, the 

 south shore of Lake Erie in New York rises abruptly from the water and 

 the influence of the lake is appreciable for a distance of only a few miles 

 inland; while the influence of Lake Micliigan, because of the gentle slope 



