474 MR ROBERT COCKBURN MOSSMAN ON 



Hail. {Table XVIII.) 



Hail showers may be divided into three sections : (l) the spring maximum, which 

 extends from February to May, this being almost entirely made up of cases of " graupel " 

 or soft hail ; (2) cases associated with thunderstorms, from June to September ; and 

 (3) ill-defined falls, principally " graupel", from October to January. Looking at the 

 annual values, it will be seen that hail is most frequent with N.W., N., and N.E. winds, 

 a large number of cases occurring with the N.W. and northerly winds which blow in 

 the rear of a cyclonic disturbance. Very few cases are recorded with south and south- 

 east winds. The spring maximum differs but little from the annual values, the only 

 pronounced feature being that hail with northerly winds is 3 per cent, greater than 

 with N.E. winds, whereas in the case of the annual values, N. and N.E. winds give 

 practically the same percentage. 



Gales. {Table XIX.) 



On the mean of the year, gales are most frequently recorded with winds from the 

 S.W. and W., while very few occur when the direction is North. The barometric 

 gradient is thus much steeper with a S.W. than with a North wind. The seasonal 

 results present few features of interest, with one important exception, viz., in winter, 

 when there is a well marked secondary maximum with winds from the N.E. Those 

 N.E. gales cause great damage and loss of life on the East Coast among the seafaring 

 community. 



Thunderstorms. {Table XX.) 



An examination of the summer thunderstorms, from May to August, shows that they 

 occur most frequently with south-east and south winds, which prevail in the south-east 

 quadrant of the shallow depressions with which the thunderstorm is associated. Very 

 few cases are recorded with south-west and northerly winds or when the air is calm, 

 as the thunderstorm is usually accompanied by a squall. The winter thunderstorms 

 and other electrical phenomena almost always take place with west or south-west winds 

 which accompany the deep cyclonic storms so prevalent at this season. 



Fog. {Table XXI.) 



Fog, as is to be expected, occurs most frequently when the air is calm, but the values 

 with N.E., E., and S.E. winds are also high ; indeed, nearly all the fogs in spring and 

 summer are associated with winds blowing off the North Sea. The few cases observed 

 with S.W., W., and N.W. winds take place in winter during hard frost, just before a 

 thaw. 



