NO. 17.] 



WIND. 



309 



WIND-VELOCITY. ANNUAL PERIOD. 



The following Table gives the mean velocity of the wind for the various 

 months. The numbers are the same as those in the last column in the table 

 on page 289. 



These means give an annual mean of 4-48 m. p. s, corresponding to Wind- 

 Force 3-5, Beaufort Scale. The monthly mean velocity is below the annual 

 mean in November, December, January, March, April, July and August, and 

 above the mean m October, February, May, June and September. Minima 

 occur in November, April and August, maxima in October, February 

 and May. 



The monthly means do not show any regular annual period. PI. I. 

 (mean v. — 1 cm. = 1 m. p. s.; diff. fr. mean). 



The annual march of the frequency of the fresher winds with a velocity 

 above 10 m. p. s., is shown in the following table ; the numbers are the same 

 as those in the column "Total" of the table on page 305. 



From October to March, the frequency of the fresher winds is above the 

 monthly average for the year. From March to September it is below, with 

 the exception of May, which is slightly above. The summer season is gener- 



