272 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 70 



Dr. Clayton takes it for granted that the variations in the solar 

 radiation must have a direct effect upon the temperature at the 

 earth's surface, and he consequently thinks that in a region where 

 there is a positive correlation between the variations in tempera- 

 ture, and the variations in solar radiation, an increase of temperature 

 is directly due to an increase of solar radiation and vice versa. The 

 negative correlation in other parts of the world he, however, thinks 

 to be a secondary result of the changes in solar activity. As far 

 as we understand him this must be caused chiefly by the transport 

 of colder air from higher latitudes. He considers the most prob- 

 able explanation to be " that tropical areas, and especially the tropi- 

 cal land areas, are the parts most heated by the increase of solar 

 radiation. This heating causes an expansion of the air of the tropics 

 and an overflow toward the temperate zones, particularly towards 

 the cooler ocean areas in this zone. The final result would be a 

 fall of pressure in the tropics and a rise in the temperate regions 

 causing an intensification of the normal pressure belts of the earth." 

 He consequently examined the variations in the pressure at several 

 stations in various parts of the globe, and comes to the conclusion 

 that these pressure variations really verify the correctness of his 

 view. The stations examined are, however, too few to base any real 

 conclusions on, and the correlations between the pressure variations 

 and the variations in solar radiation are in most cases very small. He 

 thinks, however, that this indicates " that the pressure changes are 

 the result of the temperature changes induced in the air by variation 

 of solar radiation." 



With his view of the causes of the temperature changes. Dr. Clay- 

 ton has some difficulty in explaining how it is that " the effect of 

 the solar change does vary from negative to positive at the same 

 place, and while there may be a seasonable change there are also 

 changes which cannot be explained in this way, and the reason for 

 which remains yet to be found." He suggests, however, that " these 

 diverse effects appear to be associated in some way with shifts in 

 the centers of action in the atmosphere, as for example the shift 

 of the anticy clonic center in the Atlantic and Pacific oceans, and that 

 of the low pressure center near Iceland and the Aleutian Islands." 



He furthermore says : " I am led to infer that an oscillation in the 

 areas of positive and negative departures is characteristic of all 

 effects of solar changes in the earth's atmosphere, and has been one 

 of . the reasons why the relation between atmospheric phenomena 

 has been difficult to detect, and why periodic changes of all kinds 

 have been masked." 



