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Den falder, i det Hele taget, i nogenlunde samme Retning
som den normale Vind paa Havet; men der er ogsaa
Afvigelser, saaledes som man kan vente, da Resultanten af
alle Aarets Vinde ikke behøver at falde sammen med
Retningen af den Vind, der er den hyppigste.
De sterkeste Vinde træffe vi i de nordlige Dele af
Østhavet og af Grønlandshavet samt i Nordsøen, de
svageste ved Lufttrykkets Minimum. I de to Minima samt i
det secundære Maximum söndenfor Island (03° N. 14° W.)
er der Vindstille. Ved Isgrændsen er der secundære
Maxima af Vindhastighed. Söndenfor Lufttrykminimet
herske sydvestlige Vinde over en Trekant mellem Island,
Skotland og Nordkap. I de polare Dele af Havet herske
nordlige og østlige Vinde.
arrows, with a point, show the direction of the most
prevalent wind during the course of the year. On the whole,
it takes much the same direction as the normal wind at
sea, though differences are found to occur, as indeed we
have reason to expect, since the resultant of all the winds
of the year need not have the same direction as the wind
which is the most frequent.
The strongest winds arc met with in the northern
parts of the Barents Sea and of the Greenland Sea, as
also in the North Sea, the lightest in the locality of the
minimum of pressure. In the two minima and the
secondary maximum south of Iceland (lat. 03° N, long. 14°
W), there is a calm. At the ice-limit, occur secondary
maxima of wind-velocity. South of the minimum of
pressure, south-westerly winds prevail over a triangular tract
extending between Iceland, Scotland, and the North Cape.
In the Arctic parts of the ocean, the prevailing winds
are northerly and easterly.
3. Vind-Strømmen.
Den Hastighed, som en Vind af en vis Styrke, ved
at blæse i Længere Tid, er istand til at give Vandet i
Havets Overflade, liar jeg søgt at findé ved at studere de
righoldige Data, der ere givne i de af Meteorologicai Office
i London udgivne Verker: Charts of Meteorological Data
for Square 3. Lat. 0°— 10°N, Long. 20°—30® W og Charts
of Meteorological Data for nine ten degree Squares Lat.
20° N—10" S, Long. 10°—40° W. I disse Felter af det
æquatoriale Atlanterhav blæse nemlig Passatvindene med
den ønskelige Stadighed i Retning og Styrke, og begge Grene
af JEquatorialstrømmen, clen nordlige og den sydlige, løbe
med betydelig Hastighed, for en stor Del i de herskende
og stadige Vindes Retning. Som vi senere skulle se, er
Havstrømmens Hastighed afhængig, foruden af de herskende
Vinde, ogsaa af Fordelingen af den specifiske Vægt i
Havet, der kan foranledige Afvigelser i Havoverfladen fra
Niveaufladen, og saaledes fremkalde Strømninger. Hertil har jeg
ved nærværende Undersøgelse ikke kunnet tage fuldt Hensyn.
Imidlertid maa det bemerkes, at den Virkning, de ulige
specifiske Vægter have til at frembringe Strøm, er ringe i
Forhold til Vindens Virkning — undtagen under Kysterne,
hvor Elvene udgyde sit ferske Vand over det salte Havs
Overflade — og saaledes i Æquatorialegnene, hvor de constaiite
Vindes Hastighed fer stor (10 m. mod højst 4 m. p. S. i
Nordhavet), af underordnet Betydning. Hertil kommer, at
Sammenligningen mellem Strømmens Hastighed og Vindens
Hastighed i Æquatorialegnene ikke kan gjøres directe, idet
den sidste først maa udledes al’ den observerede Vind-Styrke
efter Beaufort-Skalaen. Herved opstaar en Usikkerhed, eier
turde være af samme Orden som den, Undladelsen af at
tage Hensyn til de specifiske Vægter medfører. Forøvrigt
forer Betragtningen af Guineastrømmen, der med sin
øst-gaaende Bevægelse paa den nordlige Halvkugle antyder en
Depression af Havoverfladen svarende i Beliggenhed til det
3. The Wind-Current.
The velocity which a wind of a given force is enabled,
by blowing for any length of time, to give the water of
the surface of the sea, I have sought to determine by
studying the copious supply of data furnished in the
publications of the Meteorological Office in London, viz.: —
"Charts of Meteorological Data for Square 3: lat. 0°—10°
N, long. 20°—30° W;" and "Charts of Meteorological Data
for nine ten-degree Squares: lat. 20° N—10° S, long. 10°—40°
AV." Throughout these tracts of the Equatorial Atlantic,
the trade-winds are namely found to blow with the requisite
constancy in direction and force, and both branches of the
Equatorial Current, the north and the south, flow with
considerable rapidity, taking in a great measure the direction
of the prevailing and steadily-blowing winds. As will
afterwards be shown, the velocity of the ocean-current depends,
apart from the influence of the prevailing winds, also on
the distribution of the specific gravity of the sea-water,
which can occasion deviations in the sea-surface from the
surface of level, and thus give rise to currents. To this
circumstance, however, I could not take full regard on the
present occasion. Meanwhile, we must bear in mind that
the influence unequal specific gravity exerts in producing
currents is but slight as compared with the influence of
the wind — save near the coast, where the rivers empty
their fresh water over the surface of the salt sea — and
thus in the equatorial regions, where the velocity of the
constant winds is great (10 m. as contrasted with at most 4 m.
per see. in the North Ocean), has but subordinate importance.
Moreover, the comparison between the rate of the current
and the velocity of the wind cannot be made direct in the
equatorial regions, since the latter of the two must first be
educed from the force of the wind, observed according to
Beaufort Scale. This gives rise to an uncertainty,
possibly of the same order as that resulting from the omission to
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