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193
Bemerkning. Det hænder ikke sjeldent, at, paa de
norske meteorologiske Stationer, Luftens Middeltemperatur for
Januar Maaned er højere end for December og for
Februar. I Normalmedia for et Tidsrum af 20 Aar
forsvinder vel denne Anomali, men samtlige Stationer fra
Stad til Nordkap faa for Januar en Normaltemperatur,
der kun er lidet lavere end Decembers, men merkelig højere
end Februars1. Der indtræder aabenbart i Januar en
Forsinkelse i Luftens Afkjøling paa den nævnte
Kyststrækning. Det er denne, som mest directe bliver berørt af
den atlantiske Strømning. Det er ligesom en Varmebølge
i Januar passerede forbi i Havet. Gaa vi med en
Strømhastighed af 10 Kvartmil i Døgnet langs Strømbanen
sydover, komme vi i August, den varmeste Maaned, til den
50. Breddegrad i Atlanterhavet. Gaa vi mod Nord, komme
vi i Sonimerniaanederne til Havet Nord for Novaja Semlja.
Men her gjøre andre Forhold sig gjældende. Som bekjendt
fandt Woyprocht her om Sommeren en Vandmasse .af —2°,
om Vinteren af —1°.5. Dette lader sig imidlertid forklare.
Havet er forholdsvis grundt og paavirkes desto lettere af
Atmosfæren. Om Vinteren herske sydlige og sydostlige
Vinde, der føre det vistnok afkjølede, men relativt varmere
Vand fra Østhavet derop. Om Sommeren derimod herske
nordlige Vinde, og disse føre det indre Sibiriske Ishavs
til —2° afkjølede Vand sydover.
fact. One remark only on this subject. It occurs not
infrequently that, at the Norwegian Meteorological Stations,
the mean temperature of the air for the month of January
is higher than the mean for December and for February.
In normal means for a period of 20 years this anomaly is
found to disappear; but all the Stations from Stad to the
North Cape exhibit for January a normal temperature but
little lower than the normal temperature for December,
though remarkably higher than that for February.1
Manifestly, in the month of January a retardation must take place
in the cooling of the air along the said extent of coast. It
is this part that is acted on most directly by the
Atlantic current. A wave of heat would seem, as it were,
to pass by in the sea during the month of January.
Proceeding southward, with a current-velocity of 10 nautical
miles in 24 hours, along the path of the current, we
arrive in August, the warmest month of the year, at the
50th parallel of latitude in the Atlantic Ocean.
Proceeding northward, we reach in the summer months the sea
north of Novaja Semlja. But here other conditions assert
their influence. Weyprecht, we know, found there in
summer a mass of water of —2°, in winter one of — 1 ,°5.
This however will admit of explanation. The sea is
comparatively shallow, and hence the more exposed to
atmospheric influence. In winter, the prevailing winds are
southerly and south-easterly, and carry up to that region the
cooled, but relatively warmer water from the Barents Sea.
In summer, on the other hand, northerly winds prevail; and
these carry southward the water from the inner tracts of
the Siberian Arctic Ocean, cooled to —2°.
13. Nordhavets Overflade.
Ved Constructionen af Strømfladen have vi antaget
Lufttrykket constant over hele Havet. I Virkeligheden or
dette ikke Tilfældet. Lufttrykket overtager en Del af det
Tryk, som vi have tillagt Strømttaden. Den virkelige
Overflade er Strømfladen, nedtrykket af Lufttrykket. Denne
Nedtrykning beregnes saaledes. I Strømfladens dybeste
Punkt er Lufttrykket 755.7 mm og Fladens verticale
Ordinat —0.01 m. Kaldes Lufttrykket i et andet Punkt b,
saa er i dette Punkt Overskuddet af Lufttryk b —755.7 mm.
Da Kviksølvet er 13.5959 Gange tungere ond Ferskvand
13.5959
og , Gange tungere end Søvand af Tætheden 6’,,,
svarer til en Kviksølvsøjle, der er b —755.7 mm høj, en
Vandsøjle af (b —755.7) Millimeter. Vi have før (PI.
XXXI} regnet med Lufttrykket, reduceret til
Normaltyngden. Her er Spørgsmaalet om den observerede
lvviksølv-højde og den virkelige Vandhøjde. Vi maa saaledes sætte
Havoverfladens Nedtrykning i et Punkt, hvor Vandets
Tæthed or 8„ og Lufttrykket b, lig
1 Zeitschrift fler österreichischen Oesellschalt flir Meteorologie,
1S84, S. 150 og l.M.
Den norske Nordlmvsexpedition. 11. Mohn: Nordhavets Dybder, Tei
13. The Surface of the North Ocean.
When constructing the current-surface, we assumed
the atmospheric pressure constant over the whole tract
of ocean. This, however, is not really the case. The
atmospheric pressure exerts part of the pressure we have
ascribed to the current-surface. The true surface is the
current-surface depressed by atmospheric pressure. This
depression is computed as follows. At the deepest point of
the current-surface, the atmospheric pressure is 755.7 111111.
and the vertical ordinate of the surface —0.01 111.
Calling the atmospheric pressure at another point b, then
the surplus of atmospheric pressure at this point will be
b —755.7 mm. Since mercury is 13.5959 times heavier
13.5959
than fresh water and 0 times heavier than sea-water
o„
of the density S„, a column of mercury having the height
of b —755.7 111111. will correspond to a column of water of
13.5959
(b —755.7) millimetres. Wo have previously com-
o„
pitted (Pl. XXXI I with the atmospheric pressure reduced
to normal gravity. Here we have to do with the observed
Zeitschrift der österreichischen Gesellschaft fiir Meteorologie,
1S84, p. l.’iO, 1.">1.
ratnr og Strømninger.
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