VELOCITY— HIGH MINDS AND CALMS. 



99 



Annual Varkdion of High Winds and Calms. 



An interest;! iijj; side lii^ht is tlirown on to the conditions affecting the surface air motion by 

 comparing the minib(H- of high winds and the number of cahus in the difieront months. 



Table 57. 

 High Winds ami Calms. 



Looking fii'st at the high winds we see that their frequency has the same annual variation 

 as we have already found for the mean velocity. High winds are the least frequent in the 

 summer, the minimum in November, December, and January being most marked. The large 

 proportion of high winds in February and March is clearly shown in both years, and the 

 decrease from March to April is as pronounced in the high winds as it is in the mean 

 velocity. Either June or July has a maximum of high winds in both years. Thus the annual 

 variation of high winds is the same as the annual variation of the mean velocity. 



One would anticipate that the occurrence of calms would be the reverse of that of high 

 winds, for if the conditions during any month produce an excess of high winds they can 

 hardly be favourable for calms. This, however, is obviously not the case. August, 1911, had 

 ten times as many high winds as January, 1912, and also had twice as many calms. The 



