12 ON THE ANNUAL AND DIURNAL DISTRIBUTION OF THE 



The extreme recession of the resultant direction from the north takes 

 place during the first three hours after noon in all months excepting 

 in November, when it occurs between 11 a.m. and noon, and in Decem- 

 ber, when it is between 3 p.m. and 5 p.m. It occurs in May between 

 1 P.M. and 2 p.m., but in a contrary-direction to that of all other 

 months, being 1 08° to the east of north. 



The hours of nearest approach to the north are not so well marked 

 and are included within wider limits. For most months they were 

 found between midnight and sunrise, but in May, June and November 

 they occur in the early part of the night. The angular diurnal range 

 in the direction of the resultant is ISO*^ in July (its maximum) and 

 15° in November (its minimum). The quarterly averages of the diur- 

 nal ranges are 25*^ from December to February, 85° from March to 

 May, 152° from June to August, and 65° from September to Novem- 

 ber ; also the half yearly averages are 135° from April to September, 

 and 29° from October to March. 



MEAN RESULTANT VELOCITIES OF THE WIND IN THE DIFFERENT 



HOURS. 



By table III. it is seen that the maximum resultant velocity for the 

 whole year occurs during the hour commencing 1 p.m., and the mini- 

 mum during the two hours between 4 a.m. and 6 a.m., the progression 

 being continuous from the maximum to the minimum and to the maxi- 

 mum again, if the second place of decimals be disregarded. 



The maximum takes place in one of the three hours commencing 

 noon in every month but April and May, when it is found in the hours 

 commencing at 9 p.m. in April and at 7 a.m. in May. The hours of 

 minimum are not well marked in the separate months, and in July, 

 August and September there is a double progression. 



MEAN VELOCITIES OF THE WIND IN THE DIFFERENT HOURS. 



On the average of the year, as shewn in table IV., the maximum 

 velocity is from 1 p.m. to 2 p.m., and the minimum from 1 a.m. to 2 

 a.m. The maximum occurs in every month during one of the four 

 hours commencing noon, and the minimum in most months within 

 three hours of midnight, a prominent exception being in December, 

 when the minimum is at 7 a.m. 



