NO. 4 TEMPERATURE VARIATIONS IN THE NORTH ATLANTIC l6l 



that high winter temperatures fall coincidently with sun spot 

 maximum. 



In his valuable work on the height of the water in the great 

 Swedish lakes, Dr. Axel Wallen (1910 to 1913) has also studied the 

 variations of the air temperature at Stockholm since the middle of 

 the eighteenth century. He finds several short periods of one, two, 

 and four weeks,' and longer periods of twelve, and twenty-five or 

 twenty-six months, and then of eleven years and thirty-three years. 

 and an extremely long period of more than one hundred and ten 

 years. The eleven-year period is double, with two maxima and two 

 minima. The two minima are about equally intense, the principal 

 maximum considerably stronger than the second maximum. This 

 distribution is, however, very irregular, comes out only in the means 

 of a long series of years, and is most clearly indicated by the winter 

 temperature. It is not improbable that the period of thirty-three 

 years is divisible in a similar manner. 



The periods of a few years and of eleven years in temperature 

 variations were also found by Wallen in a series of stations in 

 North Europe as well as in Upsala and Stockholm. The maxima 

 and minima correspond completely at the different stations and 

 appear to coincide at times. Furthermore he found that the winter 

 temperatures are more strongly influenced than those of other sea- 

 sons of the year in these variations. 



Dr. Oscar V. Johansson employing smoothed five year means 

 found that the temperature, the time of harvest, and the breaking 

 up of ice in rivers in Finland apparently are somewhat more 

 favorable at and somewhat after sun spot maximum than at sun 

 spot minimum. Later (1912) by three year means of air tem- 

 perature at Helsingfors he investigated whether the sun spot period 

 is there doubled as found by Wallen (1910) for Sweden. Jo'hans- 

 son's investigations showed rather plainly a double period. The two 

 minima fall approximately with the sun spot extreme, and the two 

 maxima fall approximately three or four years later. The two 

 periods are about of equal intensity, only generally the curves at and 

 after sun spot minimum are somewhat lower than those at and after 

 the sun spot maximum. The complete amplitude is in summer only 

 half that which it is in winter and for the year 1.4° C, about the 



* Wallen thinks that these short periods depend upon the motion of the 

 moon in a similar way that Otto Pettersson attributed to the moon certain 

 oceanographic phenomena. He does not appear to have considered that his 

 short periods may be associated with the synodic rotation of the sun. 



