I20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 70 



this explanation, the temperature relations were again reversed with 

 positive anomalies over western Europe in 1907 and negative 

 anomalies in 1908. 



January-February, 1899 and 1903, as also March of 1903, showed 

 the same form of pressure distribution or wind conditions and 

 there prevailed also the same temperature distribution with negative 

 anomalies of the ocean surface and positive anomalies over Europe 

 (see pis. 18, 26, and 27). 



January, February, and March, 1904 (see pis. 28 and 29), show 

 similarly practically the same air pressure distribution and wind 

 distribution as 1903 with well-marked negative anomalies of tem- 

 perature over west Europe in February outside of south and mid- 

 dle Europe, southerly of 50° north latitude. Similar conditions 

 prevailed in the north of Norway in March, and Iceland in March, 

 and partially also in February. This may be compared with March, 

 1908, when positive anomalies appeared in the ocean in spite of cold 

 winds and negative anomalies over the whole of west Europe, but 

 not over Iceland and northern Norway. 



In March, 1905, and in January-February, 1899, there was a well- 

 marked similar form of air pressure distribution as well as of 

 temperature distribution. 



If the isobar charts are sufficiently trustworthy for our purposes 

 so that these variations are real (and this we believe) we can 

 think of no other reason for the strong discrepancies in the years 

 when the temperature distribution deviates so far from what wo'uld 

 be expected from the condition of the air pressure distribution than 

 that unusual outside conditions have come in play at least over the 

 continents. 



There are two causes which may be of importance to influence the 

 temperature of the atmosphere. First, the heat condition of the 

 ocean ; second, radiation conditions, such as the solar radiation, the 

 transparency of the atmosphere, and the nocturnal radiation. It 

 may well be that the circulation in the upper parts of the atmosphere, 

 also the vertical circulation of the atmosphere may be of impor- 

 tance, though it seems hardly probable that these should vary so 

 much from year to year when the form of the air pressure distri- 

 bution over the earth's surface is so similar. 



The first named cause, that is to say, the ocean influence, does 

 not appear adequate to produce the deviations in all cases. 



