i6 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



high latitudes than at the Equator. This fact is illustrated by the 

 upper plot in figure 13, where the pressure change for the same 

 interval on the scale is six times as great as for the tropical stations ; 

 it is also shown in figure 14, where the centers of action are near 

 50° N. In this region the oscillations of pressure are 10 times greater 

 than they are near the Equator. 



Fig. 14. — Monthly mean departures of solar radiation and of atmospheric pressure 

 from lo-year normals (2). 



Owing to the fact that the centers of action in the atmosphere 

 show marked changes of position with variations of solar activity, 

 as pointed out in the case of sun spots, it is not to be expected that 

 any high degree of correlation between solar radiation and pressure 

 can be expected for long intervals. It seemed worth while, however, 

 to compute the correlation between the monthly values of solar radia- 

 tion and of pressure for all parts of the world, using with the monthly 

 values of solar radiation the pressure at selected stations taken from 

 World Weather Records, Smithsonian Miscellaneous Collections, 



