. Climatic variation in historic and prehistoric time. o i 3 » Fig. 16. by the isohalines. The fresher surface stratum is the Baltic water which streams out from the Baltic, its lower limit being represented by the isohaline for 16 and 20 °/00 salt. Between the surface current and the under-current there exists a limiting-stratum, in which the two other water-strata are mixed. We see that the in-going and out-coming kinds of water rest on each other like two wedges, turned with their sharp ends towards each other. Korsor U { B ~ —— N -< € Fig. 17. € s | The pressure of the salt
. Climatic variation in historic and prehistoric time. o i 3 » Fig. 16. by the isohalines. The fresher surface stratum is the Baltic water which streams out from the Baltic, its lower limit being represented by the isohaline for 16 and 20 °/00 salt. Between the surface current and the under-current there exists a limiting-stratum, in which the two other water-strata are mixed. We see that the in-going and out-coming kinds of water rest on each other like two wedges, turned with their sharp ends towards each other. Korsor U { B ~ —— N -< € Fig. 17. € s | The pressure of the salt water-masses from the Ocean drives in the lower wedge, and the pressure of all the river-water that is collected in the Baltic presses out the upper water-wedge. The re- sult is an outward flowing surface-current (the Baltic stream) and an in-going under-current. It was first believed that these currents were continuous and that the one was dependent on the other, so that a greater out-current at the surface necessitated a more rapid inflow of salt water below, in order to preserve the balance in the exchange of water between the Baltic and the Ocean. A. W. Cro- nander, however, made some observations at the light-ships in the Cattegat, which showed that both currents were not always active at the same time. Then the opinion was adopted that it would be the result of the wind and the barometrical pressure over the North Sea if the lower wedge was pressed inwards more powerfully than the upper wedge was pressed outwards: for occasions are imaginable when the under wedge is pressed inwards with such force that its salt-water masses dam up the surface-current, so that the latter ab- solutely cannot make its way out. The reverse would be the case if the water-pressure, or the wind- and barometrical pressure, were strongest over the Baltic; the out-going water-wedge in the Great Belt then being able to fill the whole of the Belt all the way to the bottom and prevent the en
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Keywords: ., bookcollectionbiodiversity, bookcontributorsmithso, bookyear1914
