106 
axe. Det er ikke den varme Strøm fra Syden, der dukker 
under, men den samme, der afkjøles paa sin Overflade. 
Observationerne fra den norske Kyst, navnlig fra 
Lødingen og Altenfjorden, samt fra Grønlandshavet have 
vist os, hvorledes Temperaturens aarlige Vandring her fore- 
gaar under Lufttemperaturens Indflydelse. Vi kunne ogsaa 
forstaa, hvorledes Vinterkulden lægger sig ud over Havets 
Men hvorledes 
Overgangen ude 1 det aabne Hav sker fra Vinter til Sommer, 
derom kunne vi vere i Tvivl. Vi kunne tænke os, at Luften 
om Vaaren opvarmer de øvre Lag, hvorved der vilde frem- 
Overflade og gjør denne koldere end Dybet. 
komme et Minimum af Varme under Overfladen, der, efter- 
haanden som Opvarmningen skred frem, vilde synke dybere 
ned, indtil Temperaturen, som om Sommeren, aftog stadig fra 
Overtladen til 100 Favnes Dyb. Dette vilde svare til, hvad 
der finder Sted under Kysten. Eller vi kunne tænke os, 
at det fra Syden tilstrømmende Vand tiltog i Varme i 
Vaarens Løb, og saaledes, førende den højeste Temperatur 1 
Overfladen, afloste Vandlagene fra Vinteren. Paa et og 
samme Sted vilde om Vinteren Isothermernes øverste Del 
være bøiet tilbage mod Syd (som mellem 70° og 73° N. Br. 
i Tversnit XX VIII); om Vaaren vilde efterhaanden Iso- 
thermerne rette sig op, idet de antog sydligere Egnes 
Character (62° til 67° N. Br. i Tversnit XX VIII), og ende 
med om Sommeren at pege med sig øverste Del mod 
Nord. Eller Temperaturcurven for Stedet, der om Vinteren 
skraanede med sin øvre Ende mod Kuldegraderne, vilde om 
Vaaren efterhaanden blive mere og mere vertical, overskride 
denne Stilling og helde om Sommeren med sin øvre Ende 
mod de højere Varmegrader, uden at frembyde Inflexions- 
punkter. Den sidste Betragtningsmaade antager Jeg kom- 
mer Virkeligheden nærmest, da Luftens Temperatur om 
Vaaren og idethele over Havet er lavere end Havoverfla- 
dens, og da Strømninger, udgaaende fra varmere Egne, © 
kunne paavises at være tilstede i de Dele af Nordhavet, 
hvorom her er Spørgsmaal. 
Over det norske Hav ligger 1 alle Maaneder gjen- 
nemsnitlig et Minimum af Lufttryk. Sterkest udpræget er 
dette i Vintermaanederne!. I disse ligger et Maximum af 
Lutttryk over den centrale Del af den skandinaviske Halvø. 
Ifølge den bariske Vind-Lov blive de herskende Vinde 
Landvinde. Fra alle Kanter, fra Øst-Island, fra Norge, 
fra Spidsbergen, fra Grønlandsisen strømme disse Vinde 
ud over Nordhavet. Disse Egne have om Vinteren en 
Luft-Temperatur, der er meget lavere end den over Havet”; 
de herskende Vinde bringe den kolde Landluft ud over 
de Strækninger af Havet, der ligge ved Kysterne (Isgrændsen). 
De afkjøle Havets Overflade, sterkest ved Kysten, mindre 1 
større Afstand fra denne, hvor de opvarmes af det varmere 
Hav. Dette er Landkulden, som lægger sig over Havet, 
1 Oestr. Zeitschrift fiir Meteorologie 1883. 
? Sammesteds. Kart over Luftens Temperatur 1 Januar. 
least sensibly over the thermal axis for the air and the 
sea. It is not the warm current from the south dipping 
down, but this current cooled off at its surface. 
The observations from the coast of Norway, in par-— 
ticular Lodingen and the Altenfjord, together with those 
from the Greenland Sea, have shown us the annual vari- 
ation of the temperature here as affected by the temper- 
ature of the air. We can, too, comprehend how the cold 
of winter extends over the sea-surface, making it colder 
than the water of the deep. But in what manner the 
transition from winter to summer proceeds out in the open sea, 
we have reason to question. The air in spring might 
be assumed to warm the upper strata, and thus give 
rise to a minimum of heat beneath the surface, which, by 
degrees, as the warming progressed, would sink deeper down, 
till the temperature, as in summer, was found to steadily 
diminish from the surface to a depth of 100 fathoms. This 
mode of propagation would agree with that observed at the 
coasts. Or, we might imagine the flux of water from the 
south to increase in heat during the course of spring, and 
thus, with the highest temperature at the surface, to sup- 
plant the winter-strata. In one and the same place, the 
uppermost part of the isotherms would back 
towards the south during winter (as between lat. 70° and 
73° N, in section XXVIII); in spring the isotherms would 
gradually rise up, assuming the character peculiar to more 
southern regions (lat. 62° to 67° N, im section XX VIII), 
and terminate with their uppermost extremity pointing in 
summer towards the north. 
curve 
Or the temperature-curve for 
the place in question, which during winter sloped with its 
upper end towards the lower temperatures, would in spring 
gradually become more and more vertical, then pass on and 
incline during summer with its upper extremity pointing 
towards the higher degrees without exhibiting any points 
of inflexion. The last view of the 
opine, the true conditions nearest, since the temperature 
subject comes, I 
of the air in spring, and generally above the sea, is lower 
than that of the sea-surface, and as currents flowing from 
warmer regions can be shown to exist in those parts of 
the North Ocean we have to deal with here. 
Over the Norwegian Sea extends during all months of 
the year, on an average, å minimum of atmospheric pressure. 
Most prominent, this is found to be in winter." During 
that season a maximum of atmospheric pressure lies over 
the central part of the Scandinavian peninsula. According 
to Buijs Ballot’s Law, the prevailing winds are land-winds. 
From all points of the compass — East-Iceland, Norway, 
Spitzbergen, the ice of the Greenland Sea — these winds blow 
out over the North Ocean. The said regions have in winter 
a much lower atmospheric temperature than that observed 
over the sea;? the prevailing winds bring with them the cold 
land-air and spread it over the traets of ocean approximating 
the coast (ice limit). They cool down the surface of the sea, 
inshore most, less at a greater distance from land, where 
1 Oestr. Zeitschrift fiir Meteorologie, 1883. 
> Tbid. Map of Atmospheric Temperature for January. 
