60 



MASS. EXPERIMENT STATION BULLETIN 402 



Table 9. — Moon Phases and Frost Occurrence on Cranberry Bogs. 



Month 



Number of Frost Nights During 7-day Periods 

 Beginning with Dates of Moon Phases as Indicated 



Bright Half of Moon 



Dark Half of Moon 



First 

 Quarter 



Full 

 Moon 



All* 



Last 

 Quarter 



New 

 Moon 



Percentage 

 of Frost 

 Nights in 



Dark Half 

 of Moon 



Massachusetts 1912 to 1942. inclusive 



May 31 33 65 44 44 88 57.5 



June 4 15 4 7 11 68.8 



August 3 3 6 1 1 2 25.0 



September 25 20 46 19 13 33 41.8 



October 70 72 144 80 71 155 51.8 



All 133 129 266 148 136 289 52.1 



New Jersey 1906 to 1942, inclusive 



May 17 25 44 18 22 43 49.4 



June 3 2 5 14 5 50.0 



September 5 7 12 14 9 23 65.7 



October 30 22 58 21 32 55 48.7 



All 55 56 119 54 67 126 51.4 



Wisconsin 1906 to 1941, inclusive 



May 65 63 139 68 60 134 49.1 



June 10 16 29 18 26 46 61.3 



July 1 2 4 4 2 6 60.0 



August 16 25 42 10 13 25 37.3 



September 74 63 142 57 60 122 46.2 



October 34 41 76 33 41 77 50.3 



All 200 210 432 190 202 410 48.7 



* These figures include not only the frost nights of the moon-phase periods, but also the few 

 frost nights that came between the periods of the first quarter and full moon and of the last quarter 

 and new moon, respectively. 



BOG PROTECTION FROM FROST 

 Bog Surroundings 



Bog locations close to and usually leeward from extensive shallow salt water or 

 large fresh water ponds or reservoirs or considerable streams are generally warmer 

 than those elsewhere because of water vapor and heat brought to them by air from 

 the bodies of water. Locations closely girded by much higher land or tall woods, 

 because of restricted air circulation, are more frosty than those entirely open or 

 with considerable dingles leading to lower land or to areas of water. With other 

 conditions the same, the central parts of large bogs which are both long and wide 

 have more air movement on cold nights and so are less frosty than other places. 



Clearing trees and brush from the uplands around a bog allows more air move- 

 ment over it on cold nights. It is hard to say how much this affects minimum 

 bog temperatures, but it seems to raise them often two to four degrees. ^3 It is 

 more helpful with small bogs than with large ones. The clearing must be ex- 

 tensive and reach a real opening (Fig. 11) to be effective. Clearing a little back 

 from a small bog, half an acre or less, may do more harm than good by removing 

 partial shelter from night sky exposure. ^^ 



Grass, especially when much of it is dead, strongly restricts the flow of heat 

 into and from the ground,''^ and it radiates heat to the sky faster than bare 



'^^Judging by comparisons of the minimum temperatures of different bogs in the same neighbor- 

 hood before and after clearing around some of them. 

 ^^Schoonover, Brooks, and Walker, op. cit., p. 14. 

 '^^Geiger, op. cit., p. D8 



