470 



H. MOHN. METEOROLOGY. 



[norw. POL. EXP. 



The Table shows that we have the ordinary solar diurnal period of the 

 temperature of the air, with a minimum in the morning and a maximum in 

 the afternoon, in the months of March, April, May, June, July, August and 

 September, or that part of the year in which the sun is above the horizon during 

 some, or all, of the 24 hours. In the months of October, November, December, 

 January and February, when the sun is scarcely above, or altogether below, 

 the horizon during the 24 hours — our dark season — , we meet with 

 different forms of the diurnal period. Only in 4 instances, viz. October 1894, 

 November 1894, February 1894 and 1895, do we find the higher temperatures 

 during the day and the lower temperatures during the night, but in 11 instan- 

 ces we have the daytime colder than the night. In December there is a 

 highest maximum about midnight, and a second maximum in the afternoon. 

 A comparison between the amount of the diurnal range and the correspond- 

 ing amount of clouds, seems to indicate that greater cloudiness is combined 

 with a smaller temperature-range and vice versa. 



A closer approximation to the normal diurnal period is gained by taking 

 the means for 3 (or 2) years of the values of D. f. m. for every month. 

 These means are given in the Table below. This Table also gives the 

 "mean ordinate", the amount and hour of the minimum and maximum, 

 the diurnal range, and the mean latitude and longitude for the month. 



