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109
tov, som en første Tilnærmelse, i det væsentlige stemme
med de virkelige Forhold i Naturen.
Fra vort Nordhav foreligge adskillige Iagttagelser af
Vinden. Men dels hobe de sig op paa enkelte
Strækninger, der befares af Handelsskibe, dels samle de sig paa
enkelte Maaneder, i hvilke Skibsfart foregaar, medens store
Strækninger og mange Maaneder kun ere repræsenterede
ved enkelte videnskabelige eller Fangst-Expeditioner,
og-visse Dele aldrig ere besøgte hverken af Søfarende eller af
Videnskabsmænd.
Af et saadant Materiale vilde man ikke komme til
nogen tilfredsstillende Fremstilling af Aarets normale
Vindforhold.
Heldigvis tilbyder sig en anden Fremgangsmaade, der
ogsaa har den Fordel, at den med en ganske anden
Sikkerhed, end de directe Vind-Observationer, fører til Maalet.
Af de sidste Decenniers meteorologiske Undersøgelser
fremgaar som det bedst begrundede Resultat den Forbindelse,
som finder Sted mellem Lufttrykkets Fordeling og Vindens
Retning og Hastighed. Og denne Lov, den bariske
Vindlov, gjælder, for de Jorden nærmest værende Luftlag, i sin
største Strenghed netop Fænomenerne ved Havets Overflade.
Ere vi saaledes istand til at fremstille Lufttrykkets
Fordeling over Havet for det normale Aar, kunne vi deraf
med stor Sikkerhed udlede de herskende Vindes normale
Retning og Hastighed for det samme Tidsrum.
Vi begynde derfor vore Studier over Havets
Strømninger med Undersøgelsen af Lufttrykkets Fordeling i det
normale Aar.
Til Bestemmelsen af denne har jeg anvendt følgende
Observationer.
Fra de norske meteorologiske Kyststationer
Christiania, Sandøsund, Mandal, Skudesnes, Bergen, Aalcsund,
Christiansund og Vardø haves fuldstændige Observationer
for Kl. 8 a. m., Kl. 2 p. m. og Kl. 8 p. m. fra Januar 1807
af, udførte med Instrumenter, der stadig have været
con-trollerede.. Disse Observationer ere blevne reducerede til
den sande Barometerstand, saaledes som den vilde være
angivet af Normalbarometrene i St. Petersburg, Kew,
Greenwich, StockholmMiddel af de tre daglige Observationer
er antaget som Dagsinedium. Til nærværende Undersøgelse
er brugt den 16-aarige Række fra 1867 til 1882.
Lignende Observationer ere benyttede fra Stationerne
Oxø (1872 October til 1882 December), Florø (1809
August til 1882 December), Brønø (18G9 August til 1882
December). Bodø (1807 December til 1882 December), Tromsø
(18(37 September til 1882 December), Alten (1871 April
1 Om det norske meteorologiske Instituts Normalbarometer, se
Jahrbuoh des norwegisclien nieteorologischen Instituts fiir 1884:
Vor-wort, S. 1 til VII. De i min Afhandling "Meteorologi" i denne
Generalberetning givne Barometerhøjder blive at oorrigere med
+ 0.4 mm.
afford a good basis for continued research, and may, too,
as a first approximation, be found to agree in all essential
particulars with the true conditions in nature.
From the North Ocean we have divers observations
on wind. But either they crowd together throughout
particular tracts navigated by merchant-vessels, or they
refer wholly to particular months in which the navigation
takes place, so that extensive tracts and many months
of the year are but sparsely represented by the results of
an occasional Scientific Expedition or a few sealing ships,
nay, some parts of the sea have never been visited either
by seafarers in general or by men of science.
With such material, it would be quite out of the
question satisfactorily to account for the normal conditions
of the wind throughout the year.
We have, however, another mode of attacking the
subject, which, with a probability greatly superior to that
afforded by direct wind-observations, leads to the end in view.
The meteorological investigations of the last decennial periods
give, as their best founded result, the connection existing
between the distribution of atmospheric pressure and the
direction and velocity of the wind. And this law, the baric
wind-law, applies — with respect to the strata of air nearest
the earth — in its full rigour precisely to the phenomena
at the surface of the sea.
Now, provided we can determine the distribution of
atmospheric pressure over the sea for the normal year, we
shall be able to deduce from thence with very considerable
certainty the normal direction and velocity of the
prevailing winds for the same period.
Accordingly, we commence our researches on ocean
circulation by investigating the distribution of atmospheric
pressure throughout the normal year.
For determining this distribution, I have made use of
the following observations.
The Norwegian Meteorological Coast-Stations, viz.,
Christiania, Sandøsund, Mandal, Skudesnes, Bergen, Aalesund,
Christiansund, and Vardø, furnish a complete series of
observations for 8 a. m., 2 p. m., and 8 p. m., from the
month of January 1807, taken with instruments constantly
submitted to control. These observations ha ve been reduced
to the true height of the mercury as it would have been
shown by the standard-barometers of St. Petersburgh,
Kew, Greenwich, Stockholm.1 The mean of the three daily
observations has been taken as the diurnal mean. For the
present investigation, I have adopted the sixteen-years
series from 1867 to 1882.
Similar observations have been applied from the
following Stations: - Oxø (1872 October to 1882
December), Florø (1809 August to 1882 December), Brønø (1809
August to 1882 December), Bodø (1807 December to 1882
December), Tromsø (1807 September to 1882 December),
1 Respecting the Standard-Barometer of the Norwegian
Meteorological Institute, see Jahrbuch des norwegisclien meteorologischen
Instituts fiir 1SS4. Vorwort, p. I to VIT. The barometrical readings
in my Memoir "Meteorology" published in this General Report must
be increased with 0.4 mm.
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