16 



In the Little Belt there is only a small difference between the salinity at 

 the svirface and in deep water; it is about 20 "/(m or a little less. The temperature 

 at the surface is comparatively low in summer (during 1902 — 1906 on an average 

 13,7° in June, in July 15,2°, in Aug. 15,1°), comparatively high in winter (during 

 the same period 2,5° in January, 1,7° in Febr.). There is generally a strong cur- 

 rent, especially in the narrowest part of the Belt. 



In the Sound a salt bottom layer is found as far as Saltholm Tserskel, some- 

 times however passing it. The salinity greatly decreases southward in the upper 

 layers. The salinity of the bottom-layer also decreases southward; north of Hveen 

 it is 25 — 28'^/iHi at a depth of 20 M. In deep hollows the salinity may be 30 — 32°/u(i 

 and here the temperature in winter is constant for a long time. The following 

 numbers found at the lightship on Lappegrunden are very instructive. 



Average of 1883 — 94 (Meteorol. Aarbog): 



Temperature Salinity 





Mill. 



Max. 



Mill. 



Max. 



M 



1,0° (Febr.) 



17,0° (July) 



12,0 " '(in 



16,7 "/no 



11 - 



3,1° (March) 



15,7° (Aug.) 



21,0 - 



26,2 - 



17 - 



4,1° (March) 



11,5" (Sept.) 



28,3 - 



32,8 - 



23 - 



3,5° (April) 



11,3° (Oct.) 



28,3 - 



34,0 - 



North of Saltholm (1880 -1907): 



Salinity M. 10 -13 "/("., 10 M. 13— 16"/(mj. 



In the western Baltic there is also, at any rate in the summer, a contrast 

 between the surface-w^ater and the salt bottom-water, but as a considerable mixing 

 occurs the surface-water west of Fehmarn is comparatively salt, 11 — 18"(mi, and 

 has a somewhat lower temperature in summer than in the true Baltic. The salt 

 bottom-water has its maximal salinity in July and August, when it is ca. 20 "/on at 

 a depth of 20 M. In the area between Fehmarn and Gjedser— Dars— Taerskelen the 

 salinity decreases considerably in the upper water-layers eastwards. The salinity 

 also decreases somewhat in the bottom-water (ca. 15 — 20*"imi at a depth of 20 M.). 



At the lightship on Gjedser Reef the average salinity was in 1880—94: 



OM 8,7— 12,8 "/no 



8 - 9,8—13,6 - 



11 - 11,1-14,1 - 



In the Baltic round Moen, from Gjedser to Sweden, the salinity and tem- 

 perature are fairly uniform from surface to bottom. At Moen the salinity at the 

 surface is on an average ca. 8 " on, at a depth of 20 M. 8 — 10 "/"o. From this place 

 the salinity increases both at the surface and at the bottom towards the two en- 

 trances, the Gjedser— Dars— Tserskel and the Drogden Tserskel. 



To illustrate the hydrography of the Baltic round Born holm it may be 

 mentioned that the salinity of the surface-w^ater at Christianso in 1902 — 1906 was on 



