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.
182
rindelse or dot iskoldt Vand. og det vedligeholder denne
Character holt til henimod Norges Banker. Dot opvarmes
noget paa Vejen, fra oven og fra begge Sider, af dot varme
Vand, der strømmer over Islnnd-Færø-Ryggen, og af det
varmere Vand mollom Jan Mayen og Norge.
l’donfor Lofoten og Vestoraalen gjor don nedstigende
Beva’golse i do dybere Lag sig gjældende ogsaa i 300 Fa vnes
Dyb. Det nordover strømmende varme Vand drages
vestover og nedover henimod Jan Maven, som Tomperatnrkartet
Pl. XIX viser. Dot sættor altsaa tvers over dot bariske
Minimum i denne Dybde.
Kommen vestenfor Greenwich Meridian bojer
Isobarernes Botning Bev;ogolsen mod Syd. Dette er udtrykt
ved don varme Tunge paa over 2" i Sydost for Jan Mayen.
Vestenfor denne slutter Bevægelsen af det ombøjede varme
Vand sig til det kolde Vand fra Jan Maven Renden, som
det ledsager, med indbyrdes Opvarmning og Afkjøling, i
dets eycloniske Bevægelse søndenom det bariske Minimum
og videre østover og nordover.
Østenfor Tungen Ibr 2" ligger et thermisk Minimum
paa l°.l. Det er Virkningen al den opstigende kolde Strom,
der existerer i Dybet paa dette Strøg.
I Polarstrøm men spore vi den afkjølende Virkning
fra neden af Trykniiniinot paa 73° til 74" Br. mellem 0°
og 5° E. Lgd. i den låve Temperatur paa under —1°, som
den sydsydvestgaaoiule Strøm her paa dette Strøg faar.
Paa Østsiden af Jan Mavens Banke løber
Polarstroni-nion med en betydelig Fart. og bringer Kuldegraderne i en
Tunge sydover, vistnok tildels ved Sugning fra Dybet. Paa
Vestsiden af Banken maa Vandet bevæge sig. suget rundt
dons Sydpynt af don paa Nord vestsiden løbende Strøm,
imod Nordvest, imod Trykket, for sonore at bøje om i
Følge med Strømmen i Jan Mavens Rendens Hoveddel.
Denne Onibojning af Strømmen i La* af en Kyst eller
Banke er analog med Vindens Virkning paa Vandet ved
Spidsborgens Vestkyst. Virkningen beror naturligvis paa
Bankens Fonn og Stilling mod don herskende Strøm.
Hankens Fonn er i det foreliggende Tilfælde lør en Del
hypothetisk (Side 4), men .Reactionens Virkning so vi i den
forholdsvis varme Tunge, der skyder op paa Bankens
Vestside. Vi gjenfinde denne Tunge i de større Dyb og se
den i 1000 Favnes Dyb ogsaa motiveret ved’det hervauvndo
Trykmaxiinum.
Paa Kartorne har jeg søgt at antyde Bevægelsens
Retning vod Pile. Hvor Bevægelsen har en opstigende
Component, har Pilen et Punkt i Enden; hvor den har en
nedstigende Component, har Pilen en Ring i Enden.
Bevægelsens Hastighed i 300 Favnes Dyb kan vistnok
for en stor Del af Havet beregnes efter Formelen Side 17(i,
naar man sætter Afbøjningsvinkelen « = 90°, nemlig paa
de Steder, hvor Beva’gelsen foregaar parallel med
Isobarerne. Hvor Bevægelsen gaar i en Retning, der danner
Originally ice-cold water, it retains this character to
well-nigh the Norwegian banks. It gets slightly warmed
on its course, from above and from both sides, by the
warm water flowing over the Icoland-Færoe Ridge, and by
the warm water that passes between Jan Mayen and
Norway.
Off Lofoten and Vestoraalen. the downward motion
in the deeper strata makes its influence felt also at a
depth of 300 fathoms. The warn) water flowing north is
drawn westward and downward, in the direction of Jan
Mayen, as appears from the Map of Temperature. Pl. XIX.
Hence, it crosses the baric minimum at that depth.
West of the meridian of Greenwich, the direction of
the isobars turns the motion towards the south. This has its
thermic expression in the warm tongue of water, of :i
temperature exceeding 2°, south-east of Jan Mayen. West
of this tongue, the motion of the warm water, turned aside
as stated above, joins the cold water from the Jan-Mayen
Channel, which it accompanies, with reciprocal cooling and
warming, in its cyclonic motion south of the baric minimum,
and farther on towards the east and north.
To the east of the tongue for 2°. we observe a thermic
minimum of l°.l. It results from the ascending cold
current, present in the dee]) throughout this tract.
In the Polar current, we trace the cooling effect from
below of the pressure-minimum. lat. 73° to lat. 74° N,
between long. 0° and f>°E, in the low temperature, less than
— 1°, which the current setting south-south-west exhibits here.
On the oast side of the Jan-Mayen Bank, the Polar
current runs with considerable velocity, and carries the
temperatures below zero as a tongue southward, aided
no doubt by suction from the deep. On the west side of
the bank, the water must move, drawn round its southern
extremity by the current flowing on the north-west side,
towards the north-west, against the pressure, to bend round
subsequently, along with the current in the main part of
the Jan-Mavon Chan.nei. This bending-round of the current
under the lee of a coast or a bank is analogous to the
action of the wind on the water off the west coast
of Spitzbergen. The effect depends of course on the form
and position of the bank relative to the prevailing current.
The form of the bank in the present case is partly hypothetical
(p. 4); but the effect of the reaction may be seen in the
comparatively warm tongue that shoots up on the west side
of the bank. Wo again meet with this tongue in the
greater depths, and observe it, at a depth of 1000 fathoms,
also as the result of the pressure-maximum occuring there.
On the maps I have sought to indicate the direction
of the motion by means of arrows. Whore the motion has
an ascending component, the arrow exhibits a dot at the
end; where it has a descending component, the arrow
exhibits a ring at the end.
The velocity of the motion at a depth of 300 fathoms
may, it is true, for a great part of the sea, be computed
according to the formula p. 176, putting the angle of
deflection « = 90°, viz.. at places where the motion proceeds
parallel with the isobars. Where the motion proceeds in
<< prev. page << föreg. sida << >> nästa sida >> next page >>
