NO. 4 TEMPERATURE VARIATIONS IN THE NORTH ATLANTIC 253 



over the greater part of the more easterly regions of the Atlantic 

 Ocean. 



In this we find a good explanation of the partial opposition which 

 we had found earlier between the temperature curve for the middle 

 and more easterly parts of the Atlantic Ocean. That this relation 

 of opposition is not complete, as we found, is furthermore explained 

 because these more easterly fields farther south near the Channel 

 and Portugal form a transition zone between two different action 

 centers where the temperature variations have opposite courses. 

 These regions fall now under the one, now under the other influence, 

 in the manner which Hildebrandsson has already explained. 



Further to the south in the region of the trades the temperature 

 variations in the eastern part of the ocean run oppositely to the direc- 

 tion which they take farther north, since here, as we have already 

 previously said, they are to a great extent dependent upon variations 

 of the strength of the trade winds. An intensified trade wind causes 

 a fall of temperature and vice versa. Now it is the case that varia- 

 tions in the northeast trade (that is, variations in the air pressure 

 gradients in the region of the trades) coincide with variations of air 

 pressure difference in the North Atlantic Ocean, as an examination 

 of curves VIII and VI of figure 91 will show clearly. These two 

 curves coincide simultaneously very well even in many of their 

 smaller peculiarities. Since, however, the variations in the air pres- 

 sure difference agree with the variations of the temperature in Nor- 

 way, while on the other hand the variations of the air pressure 

 gradients in the trade regions go oppositely to the variations at 

 Liepe's stations in the trades, it follows that the temperature varia- 

 tions of the latter have an opposite direction to the temperature varia- 

 tions in Norway which is also shown by a comparison of the inverted 

 curve IX for Liepe's station VI with the direct curve VII for the 

 temperature in Norway shown in figure 91. 



We see therefore that an increase in the air circulation works in 

 opposite directions in different regions and these regions can often 

 lie very near one another, as for example the most easterly Danish 

 field at 0° to 9° west longitude and the most westerly Danish field 

 at 20° to 29° and 30° to 39° west longitude. Such results warrant 

 us in taking a closer view of the dependence of different types of 

 temperature variations to which we have called attention and which 

 at first sight seem subject to no law. The explanation of such rela- 

 tions is apparent from the examples we have given. An increased 

 air circulation, which corresponds generally with an increase of the 



