§NO. 4 TEMPERATURE VARIATIONS IN THE NORTH ATLANTIC i6k 



variations and the variations of magnetic storminess. Krogness goes 

 on the assumption that the temperature of the sea at sun spot maxi- 

 mum is highest in consequence of the greater intensity of solar radia- 

 tion, an assumption which for the open sea does not agree in general 

 with our results. 



In a later part of his article {" Naturen " for April, 191 7) Krog- 

 ness shows on the basis of the observations Heldde (1912-1915) 

 a period of approximately 27.3 days and one of half that length, 

 14 days, in the magnetic storminess which associates itself with the 

 synodic rotation of the sun. He finds also two very interesting 

 periods of about eight months and of two years in the magnetic 

 storminess in Christiania since 1843. These fall in with the period 

 of about 236 days of the heliocentric conjunction of the planets 

 Venus and Jupiter in combination with the yearly period of variation 

 in declination in Christiania.^ He publishes two curves : For the air 

 temperature in all Norway and for the surface temperature at Ona 

 Lighthouse. These two curves show this period of two years, but 

 somewhat irregularly, so that it occasionally has a length of nearly 

 three years, as in the interval 1883 to 1889, and occasionally is 

 shorter than two years. The temperature curves vary in a majority 

 of cases directly, but part of the time oppositely with the curve of 

 magnetic storminess in Christiania. The eight monthly period is 

 difficult to perceive in these curves.^ 



* Two periods of eight and twelve months are commensurate with one of 

 twenty-four months and the intensified action can thus be caused which has a 

 two years' period. 



^ In " Ann. der Hydr." for May, 1917, there appears a treatise " On the Rela- 

 tion of Temperature to Sun Spot Periods " by Otto Meissner. It is recalled 

 there that the same author had already (Astr. Nachrichten Bd. 189, p. 371-374) 

 shown that for Berlin the sun spot maximum corresponds with a temperature 

 minimum and a precipitation maximum, while three years after the opposite 

 extremes of phase succeed, and in the minimum between normal conditions 

 prevail. Meissner investigates in the present article the temperature varia- 

 tions in Berlin for each month of the year during seven and one-half sun 

 spot cycles from 1822 to 1907, and finds the following relation with the sun spot 

 periods. In the three winter months and the three summer months there is a 

 simple or double periodicity, most strongly marked in January and July 

 though with greatly displaced phases. In spring and autumn such periodicity 

 is not to be recognized. In January and February there is a principal minimum 

 the year after the sun spot maximum while, for example, in July there is a 

 minimum three years after the sun spot maximum and in the same year as the 

 temperature maximum in January. July shows a principal minimum at the 

 time of sun spot minimum, etc. The yearly mean shows a clearly double 

 periodicity with a principal minimum at the time of sun spot maximum or a 

 year later and a secondary minimum at the time of sun spot minimum. 



