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I de øverste Vandlag hender det undertiden, at
Temperaturen snart er aftagende, snart voxende med Dybden.
I saadanne Tilfælder er det vanskeligt, ja tildels umuligt,
at finde de rigtige Temperaturer med Indexthermometret.
I Danmarkstrædet er Lieutenant Caroc kommet til gode
Resultater ved Anvendelse af saavel Maximums- som
Mini-mums-Indexen og en kritisk Anordning og Discussion af
Iagttagelserne.1
En noget anden Fremgangsmaade har flere Gange
givet mig ganske vel brugbare Resultater i saadanne
Tilfalder. i hvilke Temperaturen først synker med Dybden og
derpaa voxer. Den bestaar i at fire Thermometret ud saa
varmt, at det naar de dybere Lag med et
Temperaturoverskud over det omgivende Vand. Efter at have ladet
Instrumentet accommodere sig, hvorved Minimumsindexen vil
registrere den stedfindende Temperatur, haler man det op
saa hurtigt som muligt. Instrumentets Træghed beskytter
det mod en merkelig yderligere Afkjøling, medens det
passerer mellemliggende koldere Lag. Aftager Temperaturen
atter i en større Dybde, faar man de dybere Lags
Temperatur meget godt registreret med Minimumsindexen.
Saadanne Tilfælder forekomme jevnlig om Sommeren i den
grønlandske Polarstrøm, paa de ydre Strøg, hvor den ikke
fører Drivis. Temperaturen aftager fra Overfladen til en
vis Dybde, f. Ex. 50 Favne, hvor den naar et Minimum,
stiger derpaa til et secundært Maximum, f. Ex. i omtrent
100 Favnes Dybde, og aftager tilsidst stadig indtil Bunden.
Det første Temperaturminimum faar man naturligvis
nøjagtigt bestemt ved Minimumsindexen; det andet Maximum
kan muligens blive noget afstumpet under Thermometrets
Dvælen i de ovenforliggende koldere Lag, naar man, som
sædvanligt, tager Temperaturrækken i en Sats med flere
Tlier-mometre paa forskjellige Steder af Lodlinen, der kræve
lidt Tid for at løses fra denne; de dybere Lags
Temperatur faar man derimod desto sikkrere bestemt, jo lavere
Temperaturen selv er. Blive saaledes de mellemliggende
relativ varmere Lags Temperatur muligens noget for lavt
registrerede, saa faar man dog ved Temperaturrækken udtrykt
den rigtige Karakter af Temperaturens Fordeling. Man
sammenligne Temperaturrækkerne No. 297 og 298. (Pl. VI).
Den første er taget udelukkende med Indexthermoinetre og
giver følgende Maxima og Minima: Overfladen -f- 4°.4, 60
Favne: —o°.8, 150 Favne: omtrent — o°.2, 1280 Favne ved
Bunden: — i°.4. Den anden Række er taget udelukkende
med Vendethermometret Negretti & Zambra No. 91, og giver:
Overfladen: + 4°.o, 50 Favne: — i°.2. 120 Favne: 4 00.04,
1500 Favne ved Bunden: — i°.5-
I Fjordene paa Norges Vestkyst finder man
undertiden om Sommeren, at Temperaturen først aftager fra
1 Geografisk Tidskrift. ud<rivet af Bestyrelsen for det konjrelige
danske üvografiske Selskal». 18TS. S. 08.
In the uppermost strata it will sometimes happen
that the temperature is now found to diminish, now to
increase with the depth. In such cases it is difficult, nay
well-nigh impossible, to find the right temperature with the
index-thermometer. In Denmark Strait, Lieutenant Caroc
attained excellent results by using both the maximum and
minimum index, together with a critical arrangement and
discussion of the observations.1
A somewhat different method has on several
occasions procured me very fair results, viz, when the
temperature first diminishes with the depth and then increases.
It consists of lowering the thermometer sufficiently warm
to admit of its reaching the lower strata with a
temperature exceeding that of the surrounding water. After giving
the instrument time to accomodate, when the
minimum-index will register the existing temperature, the line is
hauled in as quickly as possible. The sluggishness of the
instrument guards against any further sensible cooling
whilst passing through the intermediate colder strata.
Should the temperature again decrease at a greater
depth, you get the temperature of the deeper strata well
registered by the minimum-index. Such cases are of
frequent occurrence throughout the summer in the Greenland
Polar current, viz., its outer tracts, where there is no
drift-ice. The temperature diminishes from the surface to a
certain depth, e. g. 50 fathoms, where it reaches a
minimum, then increases to a secondary maximum, e. g. at a
depth of about 100 fathoms, after which it steadily
diminishes clown to the bottom. The first minimum of
temperature will of course be accurately determined by the
minimum-index ; the second maximum may possibly be
somewhat reduced during the stoppage of the thermometer in
the superincumbent colder strata, when, as is generally the
case, serial temperatures are taken in one operation
with several thermometers attached to different parts of
the line, because a little time is required to detach
the instruments; the temperature of the deeper strata
on the other hand is determined with the greater accuracy
the lower the temperature. Now, should, perhaps, the
temperature of the intermediate and relatively warmer
strata be registered a. little too low, the whole series will
nevertheless express the true character of the distribution
of temperature. Compare the serial temperatures Nos. 297
and 298. (Pl. VI). The first was taken exclusively with the
index-thermometers and gives the following Maxima and
Minima: Surface 4°.4; 60 fathoms — o°.8; 150 fathoms about
— o°.2; 1280 fathoms (at the bottom) — i°.4. The other
series was taken exclusively with the inverting-thcrmometer,
Negretti & Zambra No. 91, and gives: Surface 4®o;
50 fathoms — i°.2; 120 fathoms o0.o4; 1500 fathoms
(at the bottom) — i°.5.
In the fjords on the West Coast of Norway the
temperature is sometimes found in summer first to diminish
1 Geografisk Tidskrift, udgivet af Bestyrelsen for det kongelige
danske geografiske SelskaK 1878, p. !>8.
lion norske Nordlinvsexpedition. 11. Mohn: Nordlmvets Dybder, Temperatur o<r Strømninger. ’>
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