4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 



marked parallelism between radio-receptivity and changes in monthly 

 values of solar radiation. 



In order to study further the relation of clouds of calcium and 

 hydrogen as seen in faculae and flocculi to solar radiation I took 

 from the publication of the Ebro Obsei^vatory all days on which 

 the area of observed clouds of flocculi exceeded 400 millionths on 

 the Ebro scale. The day on which this area crossed the central 

 meridian of the sun as seen from the earth was called zero day. 

 Then, the solar radiation measured on that day and on each of the 

 seven days preceding was averaged. The same was done for each 

 of the following days up to 21 days later. The mean values for each 

 day are shown plotted in figure i. This plot shows that the radia- 

 tion from the sun averaged lowest when the flocculi were near the 

 center of the sun. This fact indicates changes of transparency in 

 the sun's atmosphere and is interpreted to mean that the clouds of 

 calcium and hydrogen in the flocculi cut off the radiation from the 

 surface of the sun, just as water-vapor clouds cut off radiation from 

 the surface of the earth beneath them. When near the liml) of the 

 sun, however, these clouds add to the total radiation. 



II. LATITUDE EFFECT OF SOLAR CHANGES ON THE EARTH'S 



ATMOSPHERE 



Studies of the relation of solar radiation changes to meteorological 

 changes have been published in four preceding papers in this series. 

 The results of recent researches and deductions drawn from the 

 whole mass of data follow. Some readers may be inclined to think 

 that the generalizations given are based on too small an amount of 

 data, but in reality they are leased on a large amount of data accumu- 

 lated during 20 years of research. Where one example is given, many 

 others might have been presented. 



In the earlier papers of this series the first finding of importance 

 was that there was a marked latitude efl:'ect of solar radiation changes 

 on the pressure and temperature of the earth's atmosphere. Accom- 

 panying or immediately following short-period changes in radiation, 

 there was an increase in temperature and a fall of pressure in equa- 

 torial regions, a rise of pressure and a fall of temperature lietween 

 40° and 60° latitude, while at latitudes above 70° the pressure fell 

 and the temperature rose. These conditions hold true for both the 

 northern and southern hemispheres. The chart illustrating this fact 

 is reproduced in figure 2. 



Figure 3 shows how, in the average of many cases, day to day 

 changes of pressure at Honolulu are associated with simultaneous 



