Bemerkning. Det hærider ikke sjeldent, at, paa de nor- 
ske meteorologiske Stationer, Luftens Middeltemperatur for 
Januar Maaned er højere end for December og for Fe- 
bruar. I Normalmedia for et Tidsrum af 20 Aar for- 
svinder 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 Februars!. Der indtræder Januar en 
Forsinkelse i Luftens Afkjøling paa den nævnte Kyststræk- 
ning. Det er 
den atlantiske Strømning. Det er ligesom en Varmebølge 
i Januar passerede forbi i Havet. Gaa vi med en Strom- 
hastighed af 10 Kvartmil i Døguet langs Strømbanen syd- 
over, komme vi i August, den varmeste Maaned, til den 
50. Breddegrad i Atlanterhavet. Gaa vi mod Nord, komme 
vi i Sommermaanederne til Havet Nord for Novaja Semlja. 
Som bekjendt 
aabenbart i 
denne, som mest directe bliver berørt af 
Men her gjøre andre Forhold sig gjældende. 
fandt Weyprecht 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° atkjølede Vand sydover. 
13. Nordhavets Overflade. 
Ved Constructionen af Stromfladen have vi antaget 
Lufttrykket constant over hele Havet. I Virkeligheden er 
dette ikke Tilfældet. Lufttrykket overtager en Del af det 
Tryk, som vi have tillagt Strømtladen. Den virkelige Over- 
flade er Strømfladen, nedtrykket af Lufttrykket. Denne 
Nedtrykning beregnes saaledes. I Stromfladens dybeste 
Punkt er Lufttrykket 755.7 mm og Fladens verticale Or- 
dinat —0.01 m. Kaldes Lufttrykket i et andet Punkt b, 
saa er 1 dette Punkt Overskuddet af Lufttryk b —755.7 mm. 
Da Kviksølvet er 13.5959 Gange tungere end Ferskvand 
13.5959 
OG gr — 
rer til en Kviksølvsøjle, der er 6 —755.7 mm høj, en Vand- 
HODAC 
sojle af “a (b —755.7) Millimeter. Vi have for (PI. 
XXXI) regnet med Lufttrykket, reduceret til Normaltyng- 
den. Her er Spørgsmaalet om den observerede Kviksølv- 
højde og den virkelige Vandhøjde. Vi maa saaledes sætte 
Havoverfladens Nedtrykning i et Punkt, hvor Vandets Tæt- 
hed er S, og Lufttrykket 0, lig 
Gange tungere end Søvand af Tætheden S,, sva- 
‘ Zeitschrift der dsterreichischen Gesellschaft fiir Meteorologie, 
1884, S. 150 og 151. 
Den norske Nordhavsexpedition. H. Mohn: 
195 
Nordhavets Dybder, Temperatur og Stromninger. 
fact. One remark only on this subject. It occurs not in- 
frequently 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, 
Mani- 
festly, 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 At- 
lantic current. A wave of heat would seem, as it were, 
to pass by in the sea during the month of January. Pro- 
ceeding southward, with a current-velocity of 10 nautical 
though remarkably higher than that for February. + 
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. — Pro- 
ceeding northward, we reach in the summer months the sea 
north of Novaja Semlja. But here other conditions assert 
their Weyprecht, 
summer a mass of water of —2°, in winter one of —1.6. 
The sea is com- 
influence. we know, found there in 
This however will admit of explanation. 
paratively shallow, and hence the more exposed to atmo- 
spheric influence. In winter, the prevailing winds are south- 
erly 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 —20. 
13. The Surface of the North Ocean. 
When constructing the current-surface, we assumed 
the atmospheric pressure constant over the whole tract 
of ocean. The 
atmospheric pressure exerts part of the pressure we have 
The true’ surface is the 
current-surface depressed by atmospheric pressure. ‘This 
At the deepest point of 
This, however, is not really the case. 
aseribed to the current-surface. 
depression is computed as follows. 
the current-surface, the atmospheric pressure is 755.7 mm. 
and the vertical ordinate of the surface —0.01 m. Call- 
ing the atmospheric pressure at another point 6, 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 SEE 
0 
of the density S,, a column of mercury having the height 
times heavier than sea-water 
of b —755.7 mm. will correspond to a column of water of 
185969 SE AN ee 
— 3 (b —755.7) millimetres. 
Sy 
puted (Pl. XX XI) with the atmospheric pressure reduced 
Here we have to do with the observed 
We have previously com- 
to normal gravity. 
3 Zeitschrift der Gsterreichischen Gesellschaft fiir Meteorologie, 
1884, p. 150, 151. 
