The South Pole; an account of the Norwegian Antarctic expedition in the "Fram," 1910-12 — Volume 1 and Volume 2 eBook

This eBook from the Gutenberg Project consists of approximately 790 pages of information about The South Pole; an account of the Norwegian Antarctic expedition in the "Fram," 1910-12 — Volume 1 and Volume 2.

The South Pole; an account of the Norwegian Antarctic expedition in the "Fram," 1910-12 — Volume 1 and Volume 2 eBook

This eBook from the Gutenberg Project consists of approximately 790 pages of information about The South Pole; an account of the Norwegian Antarctic expedition in the "Fram," 1910-12 — Volume 1 and Volume 2.
farther eastward in a belt that is continued round the whole earth.  To the south, between this belt and Antarctica, the temperature of the great deeps is much lower, below 0deg.  C. But in the West African Deep the temperature is about 2deg.  C. higher; we find there the same temperatures of between 2deg. and 2.5deg.  C. as are found everywhere in the deepest parts of the North Atlantic.  The explanation of this must be that the bottom water in the western part of the South Atlantic comes from the south, while in the north-eastern part it comes from the north.  This is connected with the earth’s rotation, which has a tendency to deflect currents to the left in the southern hemisphere.  The bottom water coming from the south goes to the left —­ that is, to the South American side; that which comes from the north also goes to the left —­ that is, to the African side.

The salinity also decreases from the surface downward to 600 to 800 metres (about 300 to 400 fathoms), where it is only a little over 34 per mille, but under 34.5 per mille; lower down it rises to about 34.7 per mille in the bottom water that comes from the south, and to about 34.9 per mille in that which comes from the North Atlantic.

We mentioned that the Benguela Current is colder and less salt at the surface than the Brazil Current.  The same thing is found in those parts of the currents that lie below the surface.  This is clearly shown in Fig. 9, which gives the distribution of temperature at Station 32 in the Benguela Current, and at Station 60 in the Brazil Current; at the various depths down to 500 metres (272.5 fathoms) it was between 5deg. and 7deg.  C. colder in the former than in the latter.  Deeper down the difference becomes less, and at 1,000 metres (545 fathoms) there was only a difference of one or two tenths of a degree.

Fig. 10 shows a corresponding difference in salinities; in the first 200 metres below the surface the water was about

[Fig. 9.]

Fig. 9. —­ Temperatures at Station 32 (In the Benguela Current, July 22, 1911), and at Station 6O (In the Brazil Current, August 19, 1911).

1 per mille more saline in the Brazil Current than in the Benguela Current.  Both these currents are confined to the upper waters; the former probably goes down to a depth of about 1,000 metres (545 fathoms), while the latter does not reach a depth of much more than 500 metres.  Below the two currents the conditions are fairly homogeneous, and there is no difference worth mentioning in the salinities.

The conditions between the surface and a depth of 1,000 metres along the two main lines of course are clearly shown in the two sections (Figs. 11 and l2).  In these the isotherms for every second degree are drawn in broken lines.  Lines connecting points with the same salinity (isohalins) are drawn unbroken, and, in addition, salinities above 35 per mille are shown by shading.  Above is a series of figures, giving the numbers of the stations.  To understand

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The South Pole; an account of the Norwegian Antarctic expedition in the "Fram," 1910-12 — Volume 1 and Volume 2 from Project Gutenberg. Public domain.