WEATHER IN CRANBERRY CULTURE 41 



Formulas for Reckoning Minimum Bog Temperatures at 7 p. m. 

 (Eastern Standard Time) 



Let: T be the minimum bog temperature to be computed, 



DG the shelter dry-bulb temperature at East Gloucester, 



D\V the shelter dry-bulb temperature at Worcester, 



GP the dew point at East Gloucester, 



EWP the dew point at East Wareham, 



X the average between the wet-bulb temperatures at East Wareham and 



Worcester, and 

 M the lowest of the dew points at Carlisle, East Gloucester, East Ware- 

 ham, Milton (Blue Hill Observatory), Paxton, and Worcester. 



Then: 



In April (last third) T = DG + L5 M + 30 or X - 2 



6 2 



In May (1st half) T = DG -f L5 M +45 or X +3 



6 2 



In May (last half) T = DG + L5 M + 57 or X + 7 



6 2 



In June T = DG + L5 M + 64 or X +9 



6 2 



In late August and September 



(1st half) T = DG -I- 1 .5 M + 54 or X + 7 or EWP + 8 



6 2 2 



In September (last half) T = DW + GP + U or X + 5 or EWP + 6 



4 2 2 



In October (1st half) T = DW + GP + 7 or X + 3 or EWT + 4 



4 2 2 



In October (last half). . . .T = DW -f GP + 5 or X + 2 or EWP -f 3 



4 2 2 



Add 2 degrees to the computed temperature when the 7 p.m. wind velocity at 

 Worcester is over 7 miles an hour and the barometer does not rise more than ,07 

 of an inch from 4 to 8 p.m.; but subtract 1 degree if the wind velocity at Wor- 

 cester is not over 9 miles an hour and the barometer rises more than .08 of an 

 inch from 4 to 8 p.m. If, as sometimes occurs in April and October, the barometer 

 rises .15 of an inch or more from 4 to 8 p.m. with the wind velocity at Worcester 

 not over 7 miles an hour at 7 p.m., subtract 2 degrees. 



NOTE: A clear sky in the evening at all or most of the observing stations is good 

 evidence that it will be as cold as other data indicate. A damaging frost 

 rarely occurs when it is entirely cloudy at all inland stations and partly or 

 entirely cloudy at East Wareham at 7 p.m., unless the barometer rises sharply 

 from 4 to 8 p.m. 



NOTE: Wind direction is generally of little value in frost predicting on Cape Cod; 

 but, if the wind is from the north or northwest at East Wareham at both 

 noon and 7 p.m. (E.S.T.), it is especially likely to be as cold as other condi- 

 tions indicate it will be.* The barometer usually rises sharply in the evening 

 with this wind condition. A west wind in the evening is probably safer than 

 any other. 



♦Weather forecasting in the United States. W. B. No. 583, 1916, pp. 199, 201, and 208. 

 The more severe frosts on Nantucket usually come with a dying easterly wind. 



