WEATHER IN CRANBERRY CULTURE 



45 



it with warmer overlying air and so tends to prevent frost as long as It continues; 

 but it speeds transpiration and evaporation, thus drying and cooling the surface 

 soil, and leaves relatively dr}- air near the ground if it dies. Moreover, a cold 

 night wind takes heat from the soil rapidly by the apparent conductivity due to 

 turbulence. ^^ Temperatures near the ground, therefore, usually fall rapidly 

 when the wind fails in a frost}.' night. No such protective effect remains from 

 winds that fail toward morning as that continuing after low clouds clear away. 



E\"ening winds of ten miles an hour or less, general over southern New England, 

 when associated with a somewhat inactive area of high pressure, are likely to 

 calm entirel}- before morning in spite of a large pressure gradient if the pressure 

 rises rapidly during the evening. 



With other conditions the same, fruits and foliage freeze more readily in a cold 

 wind than in still air, because there is less undercooling of plant tissues when the 

 air is moving, and wind forces convection, speeding the loss of heat from the 

 plants. ^5 



Rainfall 



Frosts occur less easily if the surface soil of the countryside is full of water from 

 recent rains. ^^ There is not only a local effect of this water on any given small 

 area, as that over a cranberry bog of the water in its surface sand, but probably 

 also a mass effect from the surface-soil water of a whole region. Tables 1,2, and 

 3 show the rainfall during the week before each of the more destructive frosts 

 in the three main cranberry-growing regions, compared with the normal rainfall 

 for those periods in the three areas. ^^ 



■^^Geiger, R., Handbuch der Klimatologie, Band 1, Teil D, Mikroklima und Pflanzenklima, 1930, 

 pp. 9-10. (Partial English translation placed in the library of Massachusetts State College.) 



^^Schoonover, Brooks, and Walker, Protection of orchards against frost, Calif, .-^gr. Col. Ext. 

 Circ. Ill, 1939, p. 14. (Copies in the Middleboro library.) 



■l^Weather forecasting in the United States, W. B. 583. 1916, pp. 187, 198. 



^^Records of daily rainfall in connection with severe frosts that came before those listed here 

 are not available. 



Table 2. — Rainfall During the Week Before the More Harmful 

 Cranberry Frosts Compared With the Normal Rainfall for the Period 



— New Jersey 

 (In Inches) 



Week Preceding Frost 



Imlaystown 



Indian Mills 



Lakewood 



Rain- 

 fall 



Nor- 

 mal 



Rain- 

 fall 



Nor- 

 mal 



Rain- 

 fall 



Nor- 

 mal 



Average 



Rain- 

 fall 



Nor- 

 mal 



Sept. 8 to 14, incl., 1895 



Sept. 25 to Oct. 1, incl., 1899. 

 May 22 to 28, incl., 1902. . . . 

 Sept. 16 to 22, incl., 1904. . . . 

 May 14 to 20, incl., 1905. . . . 



.95* 

 ,1.48 



.86 

 , .00 

 . .36 



Sept. 9 to 15, incl., 1913 20 



Sept. 4 to 10, incl., 1914 00 



Sept. 4 to 10, inch, 1917 1.92 



Sept. 13 to 19, incl., 1920 00 



May 17 to 23, incl., 1921 10 



May 19 to 25, incl., 1925 1.45* 



May 21 to 27, incl., 1927 1.39** 



May 8 to 14, incl.. 1936 - 



May 24 to 30, incl.. 1938 - 



June 14 to 20, incl., 1940 - 



.70 .71 

 .00 .90 

 .90 .71 



.58 .75 

 .00 .69 



.24 .75 



80 .10 



80 .03 



80 1.53* 



80 .00 



74 .00 



1.09* 

 .57 

 .15 



1.87 

 .22 



.90 

 .90 

 .90 

 .90 

 .71 



.71 

 .71 

 .71 

 .71 

 .95 



.00 

 .20 



1.21* 

 1.20** 



.12 

 1.27 



.12 



.75 

 .75 

 .75 

 .75 

 .93 



.95* 

 1.48 

 .71 

 .00 

 .50 



.80 

 .80 



.73 

 .80 

 .73 



.15 .85 



.69 .01 .80 



.69 1.78 .80 



.69 .00 .80 



.75 .10 .73 



1.25* 

 1.05 



.14 

 1.57t 



.17 



.73 

 .73 

 .73 

 .73 

 .94 



* These rains broke, considerable drouths. 

 ** This rain broke a well-established drouth, 

 t May 1938 was the fourth consecutive month with the New Jersey rainfall less than normal. 



