NO. 15 WEATHER AND SOLAR ACTIVITY CLAYTON 25 



departures of —.000 to —.005 calories, chart (4), this area shows a 

 defect of pressure with the minimum near Nova Scotia. Chart (5), 

 for —.006 to —.010 calories, shows the center of defect northeast of 

 Newfoundland, and chart (6), for values under —.010 calories, 

 shows the center of defect over Greenland and Labrador. 



In the same way an area of excess pressure over Europe in chart i 

 moves southward to the coast of Africa in chart 3, changes sign, and 

 then moves northward over Europe with numerically increasing minus 

 values of solar radiation. In chart i a center of minus pressures is 

 found over the central Pacific west of California. This center shifts 

 south west ward to latitude 30° in chart 3, changes sign with the change 

 in radiation from plus to minus values, and then shifts northeastward 

 with increasing minus values of solar radiation. The shift of centers 

 does not appear quite so regular over the Atlantic. However, an area 

 of defective pressure near Spitsbergen in chart i is found farther south 

 in the two succeeding charts 2 and 3. With minus values of solar radia- 

 tion it becomes an area of excess pressure covering the area between 

 Greenland and Norway in charts 4 to 6. An area of excess pressure 

 moves southward from northeastern Siberia to southern Siberia with 

 decreasing positive values of radiation in charts i to 3, but the return 

 northward of the minus area is not so evident in charts 4 to 6. A 

 center of defective pressure near Bermuda in chart i shifts southward 

 and is found near the West Indies in chart 3. It then changes sign 

 with the change in solar radiation, and moves northward to the vicinity 

 of Bermuda in chart 6. 



In figure 22 an eft'ort was made to plot the shift of the different 

 centers of action. The position of the centers for dift'erent intensities 

 are indicated by letters of the alphabet. 



In general, when a center of action, either plus or minus, is found 

 in a high latitude with high values of solar radiation, a center with 

 an opposite sign is found about 30° farther south near the same 

 longitude. Both these centers of action shift southward with decreas- 

 ing plus values of solar radiation, change sign with the change in solar 

 radiation from plus to minus, and then shift northward with increasing 

 minus values of radiation. The only exception to this rule appears to 

 be in the center of action in the Pacific, about 20° N. and 140° W., 

 which apparently drifts eastward, changes sign, and then drifts west- 

 ward again. 



In the Southern Hemisphere the number of stations is too few to 

 permit one to follow the shift in the centers of action, but the simi- 

 larity of the changes north and south of the Equator, shown in the 



