Full resolution (JPEG) - On this page / på denna sida - Sidor ...
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
187
Mayen Renden og fra Trykkets Maximum østenfor Jan
Mayen bevæge sig cyclonisk tvers over Bækkenet til
Trykkets Minimum. Vi se Virkningen heraf i Isothermernes
og Isosalinernes Opadbøjning paa dette Strøg.
T Lofotdybet har Trykket sit Maximum i den
østligste Del og aftager vestover. Bevægelsen er her
vest-gaaende og nedstigende. Den udøver saaledes sin
Maxi-mumsvirkning (Isothermernes dybeste Punkt) desto længere
vest, jo større Dybden er. Se Tversnit XV, Pl. XI. I 1000
Favnes Dyb ligger Maximumstemperaturen i en større
Afstand fra Banken. I Rummet mellem begge suges, ved
den vestgaaende Bevægelse, koldere Vand ind fra Dybet
og fra Siderne.
Langs Bauken op mod Spidsbergen gaar Bevægelsen
nordover, for den største Del med aftagende Tryk og med
samme Virkning som i 500 Favnes Dyb, nemlig Tunge af
relativ højere Temperatur med Opsugning af koldere Vand
langs Banken.
Trykkets Minimum i 74° Bredde bringer Ishavets
koldeste Vand op til højere Niveauer, medens det lille
Trykmaximum i 77° Bredde holder Temperaturen forholdsvis høj.
Om Hastigheden af Bevægelserne i 1000 Favnes Dyb
er det vanskeligt at dømme, da de verticale Bevægelser
ere saa fremtrædende. En Sammenligning mellem
Isobarsystemerne i 1000 og i 500 Favnes Dyb antyder nærmest,
at Hastighederne i 1000 Favnes Dyb skulde være endnu
noget mindre end i 500 Favnes.
I 1500 Favnes Dyb ere Nordhavets tvende Bassiner
adskilte fra hverandre (Pl. XLVII). I det sydlige,
Norske-Dybet, have vi et Isobar-, Strøm- og Temperatur-System,"
der ganske ligner det i 1000 Favne. Temperaturmaximum
ved 71° Bredde ligger lidt vestligere, da den nedstigende
Bevægelse foregaar i denne Retning.
Reactionsstrømnin-gerne under Trykmaximum i Lofotdybet ere antagelig i
1500 Favnes Dyb forholdsvis sterkt udviklede, da Bunden
kun ligger lidet dybere.
I det nordre Bækken, Svenskedybet, er der ved
Sydvestranden et sterkt udviklet Trykminimum, i dets
nordlige Del et mindre Trykmaximum. Paa Bækkenets vestre
Side ere Gradienterne sterkere end paa dets østre.
Bevægelsen maa derfor gaa paa Vestsiden mod Syd og opad,
paa Østsiden mod Nord og nedad. Temperaturen (Pl. XXTV)
or overensstemmende hermed lavest paa Vestsiden og højest
paa Østsiden.
I 1500 Favnes Dyb ere Gradienterne aabenbart
betydelig sterkere ond i 1000 Favnes Dyb. Imidlertid gaar,
som vi have seet, Bevægelsen for en stor Del imod
Gradienten. De effective Gradienter blive derfor kun
Forskjellen mellem Gradienternes Størrelse paa modsatte Sider
af Bækkenerne. Og disse Forskjeller blive ringe.
Samtidig hermed vil Frictionens Virkning blive merkeligere,
paa Grund af den større Nærhed til Havbunden. Herefter
Mayen Channel and from the maximum of pressure east
of Jan Mayen can move cyclonieally straight across the
basin to the minimum of pressure. The effect of this we
see in the curving upward of the isotherms and the lines
of equal salinity throughout this tract.
In the Lofoten Deep, the pressure has its maximum
in the eastern part, diminishing towards the west. The
motion is here westerly and downward. Hence the greater
the depth, the farther west it produces its maximum effect
(deepest point of isotherms). — See Transverse Section
XV. Pl. XI. At a depth of 1000 fathoms, the
temperature-maximum lies at a considerable distance from the bank.
In the space between, colder water is sucked in by the
westward motion from the deep and from the sides.
Along the bank, in the direction of Spitzbergen, the
motion sets northward, chiefly with diminishing pressure,
and with the same effect as at a depth of 500 fathoms,
viz.. a tongue of relatively higher temperature, with colder
water drawn up by suction along the bank.
The minimum of pressure in lat. 74° N brings up
the coldest water of the Arctic Ocean to higher levels,
whereas the minor pressure-maximum in lat. 77° N keeps
the temperature comparatively high.
As regards the velocity of motion at a depth of 1000
fathoms, it is difficult to form any just conclusion, the
vertical motions being so prominent there. A comparison
between the isobar-systems at a depth of 1000 fathoms and
of 500 fathoms, would seem however to indicate that the
velocity at a depth of 1000 fathoms is somewhat less than
at a depth of 500 fathoms.
At a depth of 1500 fathoms, the two basins of the
North Ocean are separated one from the other (Pl. XLVII).
In the southern, or the NorwaJ’ Deep, we have an isobar,
a current, and a temperature-system, much resembling
that at 1000 fathoms. The temperature-maximum in lat.
71° N lies a little farther west, the downward motion
proceeding in that direction. The reaction-currents beneath
the pressure-maximum in the Lofoten Deep, are, it may be
assumed, at a depth of 1500 fathoms, by comparison highly
developed, since the bottom lies but very little deeper.
In the northern basin — the Swedish Deep — occurs
at its south-west margin a strongly developed
pressure-minimum, in its northern part a minor pressure-maximum.
On the west side of the basin, the gradients are steeper
than on the east. The motion must, therefore, on the west
side, proceed towards the south, and upwards; on the east
side towards the north, and downwards. The temperature
(Pl. XXIV), in conformity herewith, is lowest on the west
side and highest on the east.
At a depth of 1500 fathoms, the gradients are
manifestly much steeper than at a depth of 1000 fathoms.
Meanwhile, the motion proceeds to a great extent, as we
have seen, against the gradient. Hence, the effective
gradients are merely the difference between the magnitudes of the
gradients on opposite sides of the basins. And these
differences are but trifling. Moreover, the effect of friction
will be more sensible from the greater proximity to the
24*
<< prev. page << föreg. sida << >> nästa sida >> next page >>
