NO. 15 WEATHER AND SOLAR ACTIVITY CLAYTON 35 



8. The matter of especial importance considered in this paper is 

 the shifting of the centers of action in the atmosphere under the in- 

 fluence of varying intensity of solar activity. If this is a fact, then 

 no research worker in meteorology can afford to overlook it. 



9. When the earliest investigations of the relations of solar activity 

 and weather began, it was assumed that if the sun became warmer 

 the temperature all over the earth would rise. Some confirmation of 

 this view appeared to result from Koppen's finding that the mean 

 temperature over all the regions from which he was able to obtain 

 observations was higher when sun spots were at a minimum. But 

 more recent investigations have disclosed that solar radiation is on the 

 whole lower at sun-spot minimum and that with the increase of solar 

 radiation there are regions of the earth which show opposite changes 

 toward each other. Now it is shown that these regions of opposite 

 change shift position on the earth's surface. This view adds compli- 

 cations, but brings us nearer the actual facts. In the meantime there 

 has been a marked development in theory from the physical and mathe- 

 matical viewpoint, as shown by the papers of Dr. G. C. Simpson on 

 the heat balance in the atmosphere, and the studies of Brunt and 

 Fowle on the absorptive powers of water vapor on solar radiation. 



