H. MOHN. METEOROLOGY. 



[NORW. POL. EXP. 



We then have 

 the probability of precipitation 



W9 



gt 



N the total duration of precipitation in hours 



n 



r N 



- the average duration (in hours) of precipitation in a day of precipitation. 



PL IX (5 mm. = 1 hour). 



The duration of precipitation in a day of precipitation is, on an average, 

 7'38 hours. 1 There is an annual period with minima in November, July (and 

 March) and maxima in January, April (and August). Taking the means for 

 the seasons, we get 



5-af 



Winter 



Spring 

 7-76 



Summer 

 6-82 



Autumn 

 6-54 



Maximum in winter, minimum in autumn. 



Christiania has 7'1 hours, the west coast of Norway more than 13 hours. 



