NO. 4 TEMPERATURE VARIATIONS IN THE NORTH ATLANTIC 1 25 



The curve of the surface temperature, W, for March at Torungen 

 shows a surprisingly good agreement with the curve of the air pres- 

 sure gradients for March, (see pi. 48, fig. i, full-drawn curve B). 

 An even better agreement is shown by the mean between February 

 and March, which is the strong dotted curve B. 



In the other months of the year we must expect less close agree- 

 ment between the curves of air pressure gradients and the curve of 

 surface temperatures because so many other different factors are 

 operating. 



We find a tolerable agreement between the curve of the surface 

 temperatures for Ona for January and the curve of the air pres- 

 sure gradient for Stad for January, but there are exceptions for 

 the several years 1896, 1897, 1904, and 1910. The relation is no 

 better if we take the curve for December (see pi. 47, fig. i). 



The curve of the surface temperature for March at Ona Light- 

 house shows remarkably little correspondence with the curve of the 

 air pressure gradients for March. On the other hand, there is a re- 

 markable similarity to the curve of the air pressure gradients for 

 February and also to the mean curve for February and March (see 

 pi. 48. fig. i). In the other months of the year the agreements 

 between the curves for the variations in the surface temperature and 

 the variations of the air pressure gradients are not so good. For 

 example, in January, there is little similarity between .the curves 

 and in the other months there is even less. This depends upon 

 the fact that in these months the relations are more complicated 

 and besides that other conditions come into play. It must be 

 remembered that the conditions of winter and summer are opposed 

 and therefore, in the interval of time between, transition condi- 

 tions occur. 



In our figures, we give also the curves for the surface tempera- 

 ture, W, at Heliso and Utsire lighthouses. The curve for Heliso 

 shows throughout the greatest similarity to the curve for the air 

 pressure gradients for Stad, while the curve for Utsire shows 

 perhaps a greater similarity to the curve of the air pressure gradi- 

 ents for Torungen. But on the whole the results for both stations 

 are such that they form a transition between the curves for To- 

 rungen and the curves for Stad and Ona. 



RELATION BETWEEN AIR PRESSURE GRADIENTS AND AIR TEMPERATURE 

 AT ONA, TORUNGEN, AND IN ALL NORWAY 



We have introduced in our figures curves for the air temperature 

 at Ona, Torungen, and all Norway, as computed from the observa- 



