394 



H. MOHN. METEOROLOGY. 



[NORW. POL. EXP. 



The epochs for the maximum and minimum of the 3 periods, corresponding 

 to the values of A lt A t and A 3 , are: 



The 24-hours Period. The angular constant A t lies about 160 (max. 

 hour 7 h 20 m p. m.) except in September. Its range a t varies between 0.041 mm. 

 and 0.167 mm. and has maxima in February, July and September, and minima 

 in April, September and December. 



The 12-hours Period. The angle A 2 oscillates around 297 (max. hour 

 5 h 5 m ). The general rule, maximum at 10 h and minimum at 4 h , is here 

 nearly reversed. 



The value of a 2 has a regular annual period, with maxima in February 

 and September, and minima in December and July. The July minimum is 

 the lowest. This corresponds with the general rule, viz. one minimum at 

 the time of the Sun's perigee and one lower minimum at the apogee. 



The value of a 2 for the year, 0.022 mm., is rather large for the high 

 latitude of 82. 7. 





