15 
a bottom-current through the channels in the Sound and the Belts, especially the 
Great Belt, while a surface-current streams out from the Baltic in an opposite 
direction. On account of the rotation of the earth this northward so-called Baltic 
Current is forced eastward and consequently remains on the eastern side of the 
Kattegat along the Swedish coast, and for the same reason the north-going surface- 
water moves more rapidly in the Sound than through the Belts. Vice versà the 
salt bottom-current is forced westward. The boundary between the two water-layers 
is very distinct in summer, while the transition is uniform in winter. 
The salinity does not vary much in the North Sea. At the lightship on 
Horns Reef the conditions in the years 1880—94! were: 
Temperature Salinity 
Mean minimum Mean max. Mean minimum Mean max. 
O0 M..... 2,2° (Febr.) 15,8° (Aug) | 32,7 "100 33,2 0/00 
23 - .... 36° (March) 15,5° (Sept) | 33,1 0/00 33,7 loo 
The numbers are the averages of the monthly means; the variations are thus 
a little greater than indicated by the numbers. Along the coast a narrow and not 
very deep margin occurs with a somewhat lower salinity. 
The conditions in the part of the Skagerak which lies nearest Jutland are 
essentially like the corresponding part of the North Sea, the water mainly strea- 
ming from the North Sea towards the Swedish coast. 
In the waters inside the Skaw (Skagen), at every place where the depth is 
considerable, an upper, relatively not very salt layer, the temperature of which 
almost constantly follows that of the air, can be distinguished from a deeper layer 
with salter water and with special conditions as to temperature. With regard to 
the surface water, the highest temperature of the year is commonly observed in 
the beginning of August and is in the greater part of the waters on an average 
16°, while the lowest temperature of the year, which on an average is 2°, is or- 
dinarily observed in the middle of February. In fjords and bays, where the renew- 
al of the water is not considerable, the maximal temperature is however higher 
and falls in July, and the minimal temperature is lower in winter. In the deeper 
and salter water-layers both the maximal temperature and the minimal temperature 
occur later than at the surface, and the maximum temperature is lower than at 
the surface, the minimum temperature higher. The differences from the surface 
are various but are essentially regulated by the depth. 
With regard to the hydrography of the Limfjord only some few observations 
are available. In this shallow water there is only a small difference between the 
surface and the deeper water-layers. The water in the western part is most like 
that of the North Sea, the eastern part like the surface-water of the Kattegat. It 
is only for Oddesund and Aalborg that continuous observations on the surface- 
water are available. In 1902—1906 the salinity at Oddesund was on an average 
\ Meteorologisk Aarbog for 1896. 
