48 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. ']'] 



solar radiation, in the pressure at Winnipeg, and in the temperature 

 at Winnipeg, when the spot was crossing the side of the sun facing 

 the earth, and the other half of the diagram shows the changes in 

 solar radiation, pressure, and temperature when the spot was on the 

 side of the sun turned away from the earth. The temperature plot is 

 inverted, that is, high temperatures are downward. 



It is evident, as said previously, that less radiant energy reaches 

 the earth from the side of the sun on which the spot is located, so 

 that this becomes the cold side of the sun, and the opposite side the 



Table 14. — 



Mean Atmospheric Pressure and Temperature in Relation to Large 

 Sun Spots, 1921-24. 



Note: Add 

 from normal i 



29.00 to values of pressure. Temperature is departures of daily maximum 

 n degrees Fahrenheit. 



warm side. The amount of radiant energy reaches its lowest level 

 about the time the spot crosses the central meridian of the sun. 



The shorter fluctuations as well as the general trend of the curves 

 are strikingly alike in the solar radiation and in the pressure and 

 temperature of Winnipeg during the time the spot is visible, but the 

 relation is not so evident for the opposite side of the sun, probably 

 because the observations on which the means depend are very broken 

 and farther from the date of observation. The maximum "A" of 

 solar radiation occurs soon after the spots and faculae appear on the 

 eastern limb of the sun, and the maximum " B " occurs shortly 

 before the spots and faculse reach the western limb of the sun. As 



