The average duration of wind from various directions is as follows:
From the north about 16 hours each week; from the northeast, the same; from the east, 11 hours; from the southeast, 10 hours; from the south, 24 hours; from the southwest, 27 hours; from the west, 33 hours; and from the northwest 31 hours.
During an individual disturbance lasting about 36 hours, we may have 8 hours of southwest wind; 4 hours of west wind, backing during the next 4 hours to south; 2 hours of south wind; 2 hours of southeast wind; 2 hours of east wind; 8 hours northeast wind and 4 hours north wind, 2 hours northwest, when it may be considered that a new pressure distribution prevails.
The above values hold only for a storm moving with normal velocity. LOWS are often blocked by slow moving HIGHS in advance. In such cases the duration of east winds is greater.
The following table shows the marked increase in the prevalence of northwest and west winds during winter months, the decrease in north winds during July, the increase in northeast winds in May, also in east winds; the increase of south and southwest winds in July; and the falling off of southeast winds in December. See Table, page 72.
In cities near the Atlantic Coast, a continuance of northeast wind, especially in the fall and winter months, results in frequent altho not necessarily heavy rains. On the other hand a period of continued northwest and west wind is a dry period.
In summer, southeast and east winds bring fog and cooler weather; while southwest winds are favorable for the development of thunderstorms.
TABLE I.--Number of Hours the Wind Blows from Different Directions.
-------------------------------------------------------------------- Jan. Mar. May July Sept. Nov. Year Feb. Apr. June Aug. Oct. Dec.
Boreas (N) 98 74 71 70 60 40 59 59 67 80 82 96 850 Kaikias (NE) 41 46 65 94 101 55 79 79 77 91 48 30 819 Apheliotes (E) 34 37 52 58 63 48 51 51 52 58 34 31 576 Euros (SE) 37 37 45 41 54 45 62 62 52 45 39 34 534 Notus (S) 82 66 95 99 143 155 128 128 118 93 81 65 1245 Lips (SW) 112 77 81 79 118 170 135 135 133 108 119 131 1402 Zephyros (W) 180 177 155 125 107 137 125 125 108 131 169 194 1732 Skiron (NW) 160 162 183 154 98 94 105 105 113 138 148 163 1607 --------------------------------------------------------------------