117 
Den falder, i det Hele taget, 1 nogenlunde samme Retning 
som den normale Vind paa Havet; men der er ogsaa Af- 
vigelser, saaledes som man kan vente, da Resultanten af 
alle Aarets Vinde ikke behover at falde sammen med Ret- 
ningen 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 svage- 
ste ved Lufttrykkets Minimum. I de to Minima samt i 
det secundære Maximum søndenfor Island (63° N. 14° W.) 
er der Vindstille. Ved Isgrændsen er 
Maxima af Vindhastighed. Sondenfor Lufttrykminimet 
herske sydvestlige Vinde over en Trekant mellem Island, 
Skotland og Nordkap. I de polare Dele af Havet herske 
nordlige og østlige Vinde. 
der secundære 
3. Vind-Strømmen. 
Den Hastighed, som en Vind af en vis Styrke, ved 
at blæse i længere Tid, er istand til at give Vandet 1 
Havets Overflade, har jeg søgt at finde ved at studere de 
righoldige Data, der ere givne i de af Meteorological Office 
1 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° 8, 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 Æquatorialstrømmen, den nordlige og den sydlige, lobe 
med betydelig Hastighed, for en stor Del i de herskende 
og stadige Vindes Retning. Som vi senere skulle se, er 
Havstrommens Hastighed afhængig, foruden af de herskende 
Vinde, ogsaa af Fordelingen af den specifiske Vægt i Ha- 
vet, der kan foranledige Afvigelser 1 Havoverfladen fra Ni- 
veaufladen, og saaledes fremkalde Stromninger. 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 Over- 
flade — og saaledes i Æquatorialegnene, hvor de constante 
Vindes Hastighed er 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 af den observerede Vind-Styrke 
efter Beaufort-Skalaen. Herved opstaar en Usikkerhed, der 
turde være af samme Orden som den, Undladelsen af at 
tage Hensyn til de specifiske Vægter medfører. Forøvrigt 
fører Betragtningen af Guineastrømmen, der med sin øst- 
gaaende Bevægelse paa den nordlige Halvkugle antyder en 
Depression af Havoverfladen svarende i Beliggenhed til det 
/ 
arrows, with a point, show the direction of the most prev- 
alent wind during the course of the year. 
it takes much the 
sea, though differences are found to occur, as indeed we 
On the whole, 
same direction as the normal wind at 
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 aré met with in the northern 
parts of the Barents Sea and of the Greenland Sea, as 
also in the North Sea, the lghtest in the locality of the 
minimum of pressure. In the two minima and the secon- 
dary maximum south of Iceland (lat. 63° N, long. 14° 
W), there is a calm. 
maxima of wind-velocity. 
At the ice-limit, occur secondary 
South of the minimum of pres- 
sure, 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. The Wind-Current. 
The velocity which a wind of a given foree 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 pub- 
lications of the Meteorological Office im London, viz.: — 
“Charts of Meteorological Data tor Square 3:. lat. 0°—10° 
N, long. 20°—30° W;” and “Charts of Meteorological Data 
for nine ten-degree Squares: lat. 20° N—100 S, long. 109—400 
W.” 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 
As will aft- 
erwards 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 
of the prevailing and steadily-blowing winds. 
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 — saye 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 sec. 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 
Beautort Scale. 
sibly of the same order as that resulting from the omission to 
This gives rise to an uncertainty, pos- 
