proceedings: Washington academy of sciences 137 



site effects in Norway and in mid-Atlantic. An increase of air circu- 

 lation may thus have opposite effects in different regions. The sun 

 spots and magnetic elements sometimes oppose and sometimes agree 

 with the variations in pressure gradients. 



Various periodicities appear in the sun spots as well as in the ter- 

 restrial phenomena. In the sun spots there is an 8-month period cor- 

 responding with the conjunction or opposition of the planets Venus 

 and Jupiter with the sun. This same period occurs in the North 

 Atlantic gradient, and was found by Krogness in the magnetic decli- 

 nation at Kristiania. There are also periods of six and twelve months 

 in the magnetic elements, due to the position of the earth. The com- 

 bination of these 6, 8, and 12-month periods gives a 2-year period for 

 the magnetic and meteorological elements on the earth. But in the 

 fluctuations of the sun spots a similar period of two years is also dis- 

 covered, and especially noticeable are indications of minima every sec- 

 ond year. Before 1896 there is an agreement between the 2-year 

 minima of temperature at certain stations and the corresponding sun- 

 spot minima, but the agreement is remarkable in that the greatest 

 depressions in the sun-spot curve coincide with the smallest depres- 

 sions in the temperature curve; this relation ceased about 1896, hence 

 the peculiar inversion already referred to. 



Other periodicities have been recognized. A 32-33-month period 

 at Batavia may be a combination of the 2-yea]" period already referred 

 to and a 3.7-year period suspected by Lockyer. Secular changes of 

 relatively long period (35 years and over 100 years) also are probable. 

 The researches of Clayton have recognized correlations in daily tem- 

 perature and pressure fluctuations at various stations over the earth 

 and the fluctuations in the dail}^ heat radiation of the sun as meas- 

 ured by Abbot and Fowle, the same three types appearing in these 

 meteorological variations as have been noted in the long-time varia- 

 tions. Krogness recognizes^ H-da}^ and 27-day periods in magnetic 

 storms, as well as in air-pressure gradients, wind, and temperature, in 

 northern Norway. 



To summarize the results of these investigations : In different groups 

 of areas on the earth the meteorological elements (temperature, baro- 

 metric pressure, rainfall, etc.) fluctuate or pulsate, so to speak, in time 

 with one another, while in other groups of areas the fluctuations or pul- 

 sations are exactly inverted, and finally, some areas show transition 

 stages between the two. The result of all this is a very complicated 

 picture of the meteorological fluctuations. But by means of appro- 

 priate analyses we see that from this complicated and apparentlj^ 

 chaotic set of fluctuations there arises a clear picture of the very inti- 

 mate relation between all these variations and the variations in the 

 sun's activity. We have seen that even changes of very short duration 

 in the sun's radiation (of heat as well as electricitjO are distinctly re- 

 peated in our meteorological conditions and in the surface temperature 

 of the ocean. The effects of the solar variations are probably trans- 

 ferred by means of variations produced in the distribution of pressure 



