NO. 4 TEMPERATURE \ARIATIONS IN THE NORTH ATLANTIC 5 1 



of the westerly winds. Furthermore he is of the opinion that the 

 length of time is variable which is required for the influence of the 

 variations in the strength of the trade winds to make itself felt in 

 the North Atlantic Ocean through the medium of the Equatorial 

 Current. 



In a later work (1912 and 1914) Campbell Hepworth has inves- 

 tigated the relation between the variations of the Labrador Stream, 

 the variations of the surface temperature of the North Atlantic 

 Ocean, and the variations of the air pressure and temperature over 

 the British Isles. He believes he has established a certain connec- 

 tion between the three kinds of variation, although one must say that 

 this dependence is somewhat far-fetched and often yields to other 

 stronger influences which make themselves apparent. The agree- 

 ment between his curves for these variations is therefore not very 

 striking and his results are not particularly convincing. 



P. H. Galle has compared in two papers (1915 and 1916) the rela- 

 tions between the variations in the strength of the North Atlantic 

 trade winds and the variations in the height of the water and the 

 temperature in the North European seas as well as the variations in 

 the winter temperature of Europe. He comes to the conclusion that 

 there is a connection between these. But the agreement between 

 the variations of the strength of the trade wind and the variations 

 of the height of the w^ater of the North Sea, which he shows, is not 

 very great. Also the agreement between the variations of the trade 

 wind and the variations of the surface temperature of the northern 

 European seas is not particularly striking. His comparison of the 

 variations of strength of the trades and the variations of the winter 

 temperature of certain parts of Europe leads to better agreement. 

 It has been shown by several authors, that this latter is in a great 

 measure influenced by the air pressure distribution over the Atlantic 

 Ocean and Europe and also that the variations of these pressure 

 distributions depend in a certain degree on the variations in the trade 

 winds. Hence it is not improbable that the trade wind is the 

 original cause. 



Galle claims, as Campbell Hepworth also maintained, that a slight 

 connection exists between the strength of the trade winds and the 

 temperature of the British Isles, but it is indeed very small. Camp- 

 bell Hepworth found a phase displacement of about fourteen months, 

 while Galle estimated it as only two months. 



