NO. 4 TEMPERATURE VARIATIONS IN THE NORTH ATLANTIC 183 



show exact agreement they show at least with certainty that the 

 relation cannot be inverted/ These measurements lead further- 

 more to the remarkable discovery which was confirmed by coinci- 

 dent observations on Mt. Wilson and in Algeria that the radiation 

 of the sun outside our atmosphere varies considerably from time 

 to time within a few days interval, sometimes increasing, sometimes 

 decreasing. Hence our sun is in a high degree similar to the other 

 variable stars which we see in the heavens, like the star Myra. 

 According- to these measurements the theory that the observed 

 eleven-year variation in the air temperature on the earth's surface 

 follows directly corresponding variations in the output of solar 

 radiation must be definitely abandoned. 



It was particularly Blanford who advanced the second theory, 

 that depression in the terrestrial temperature at sun spot maximum 

 depends upon increased solar radiation, which produces an increased 

 evaporation of the ocean and thereby an increased formation of 

 clouds on the land, which in its turn again diminshes the solar radia- • 

 tion on the continental surfaces and causes a fall of temperature. 

 Besides this the re-evaporation of the increased rainfall would fur- 

 ther diminish the temperature. That this theory — which seems so 

 reasonable — has not so general application as was to be expected 

 must be partially explained by the fact that investigation of the varia- 

 tions in the cloudiness show that these do not have an exact rela- 

 tion with the variations in the sun spots, such as the theory assumes. 

 But there is yet another difficulty. According to this theory one 

 would expect that the surface temperature of the ocean, particu- 

 larly in the tropical regions, would be highest at sun spot maximum 

 and lowest at sun spot minimum, but this as we have seen, is not 

 the result of our collected observations. On the contrary our 

 temperature tables and temperature curves show for different parts 

 of the ocean the inverse relation, that is, lower temperature at sun 

 spot maximum and high at sun spot minimum. It may be recalled. 



^ The following values (in calories) of the solar constant were obtained 

 on Mt. Wilson : 



1905 June to Oct. 1.956 1910 May to Nov. 1.921 



1906 May to Oct. 1.942 191 1 June to Nov. 1.923 



1908 May to Nov. 1.936 1912 June to Aug. 1.940 



1909 June to Oct. 1.918 



According to this there was a maximum in 1905 which could correspond 

 to the sun-spot maximum, but on the other hand there was a minimum iq 

 1909 and a secondary maximum in 1912. 



