lO 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 



sure from 40° to 70° N., and a defect in the vicinity of the pole, while 

 the opposite signs are found in the same latitudes during low solar 

 activity. 



MEAN MONTHLY DEPARTURES FROM NORMAL PRESSURE WITH HIGH AND 

 WITH LOW SOLAR RADIATION. 



EQUATOR LATITUDE NORTH POLE LATITUDE NORTH EQUATOR 



0* 10 20 SO 40 50 eo 70 eo 90° 80 70 60 50 40 30 20 10 0° 



-l-r, 7"T T'-tt: : 



..-• i^ / _;v £_ i^;^ 



> .^ --^ ..'v. - ,'^- 



• HIGH SOLAR RADIATION 



■ LOW SOLAR RADIATION 



Fig. 5. — Mean monthly departures from normal pressure with high and 

 with low solar radiation. 



Figure 5 shows a plot across the pole of the means for the year in 

 each case. The dotted line connects the values for high solar activity, 

 and the broken line connects the values for low solar activity. Data 

 are missing from points north oi 80° so that the part of the curve 

 near the pole is interpolated. 



Fig. 6. — Mean pressure at different latitudes with different solar conditions. 



This diagram brings out clearly the opposite oscillation of the 

 pressure in latitude with high and with low solar activity. 



Figure 6 shows how these departures appear when they are added 

 to the normal distribution of pressure. In this figure the normal dis- 



