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DYNAMIC METEOROLOGY AND HYDROGRAPHY. 



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200 



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WO 



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thickness and less concentration of mass where they have their maximum of thick- 

 ness. On the first six charts representing sheets of io decibars the figures added 

 to the curves represent the average specific volumes in the sheets after a division 

 by io, and in the six charts for the sheets of ioo decibars the average specific 

 volume of the water in the sheet after a division by ioo. 



Besides charts representing the topography of isobaric surfaces, we might also 

 have drawn charts representing the pressures at level surfaces. But these would 

 have been so like the topographic ones that it would have been of no interest to 

 draw them. A glance at table 24 h shows, for instance, that in the Baltic, where 

 the density of the water is so near unity, we have in the upper sheets only to change 

 the numbers added to the curves, 9.95 into 10.05, IQ -94 i nto 2 -6 and so on. 

 Then the charts would at once be the isobaric charts for the depth of 10, 20 . . . 

 dynamic meters below sea-level. In the greater depths also a slight change in 

 the situation of the curves representing the integer values would be required. Out- 

 side the belts the change would have been a little greater. In the upper layers the 

 isobaric curves would follow each other with 5.5 per cent smaller intervals than 

 the corresponding level curves drawn in fig. 28. This percentage would increase 

 gradually downward with the increasing density due to the compression reaching 6 

 at the depth of 600 dynamic meters. As, however, the course of the curves is 

 unchanged, the two kinds of charts would be extremely like each other, the most 

 striking difference being that maxima on the one would have been minima on the 



Norwegian Sea 



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Norwegian, Submarine Channel 



Fig. 31. Profile curves of isobaric surfaces and surfaces of equal-volume 



