310 



H. MOHN. METEOROLOGY. 



[NORW. POL. EXP. 



ally quieter than the winter season. (PI. I. v. > 10 m.; 1 mm. = 10 

 cases; diff.) 



The number of days on which the velocity of the wind has reached 

 10 m. p. s. and upwards is 



The number of days with an observed wind-velocity above 10 m. p. s. 

 is above the general average (6'3) per month in September, October, November, 

 December, February and June. It is below the mean in March, April, July 

 and August. 



There are minima in March, July August and January; maxima in February, 

 June, September October. There is no regular annual period. The summer 

 season is quieter than the winter season. (PI. I, days v. >> 10; 1 mm. = 1 

 day; diff.) 



The general march of the frequency of the cases, and the number of 

 days with fresher winds, is the same from month to month. The march of 

 the mean velocity for the months has also the same character as that of days 

 with stronger winds, 15 to 18 m. p. s. ; there are 3 in November, 2 in Decem- 

 ber and 1 in February. 



The highest observed velocity of the wind being only 18 metres per second, 

 we find no storm proper along the route of the Fram. 



The following Table shows in the first row the mean number of calms, 

 reduced to bihourly observations, for each month (Table, p. 307). Dividing 

 these numbers respectively by the total number of observations made in the 

 month (12 X number of days in the month), and multiplying by 1000, we 

 get the numbers in the second row. These numbers, express (per mille) the 

 probability of calms in each month and the year. 



The mean of the first row is 6'5. 



