Archive image from page 288 of The depths of the ocean. The depths of the ocean : a general account of the modern science of oceanography based largely on the scientific researches of the Norwegian steamer Michael Sars in the North Atlantic depthsofoceangen00murr Year: 1912 PHYSICAL OCEANOGRAPHY 253 but when the red rays, for instance, are cut off, a piece of red paper will look black. The usual method of studying the transparency of the water Transparency is to lower a large white disc, noting the depth at which it ofea-water. disappears from view. The degree of transparency is found to vary
Archive image from page 288 of The depths of the ocean. The depths of the ocean : a general account of the modern science of oceanography based largely on the scientific researches of the Norwegian steamer Michael Sars in the North Atlantic depthsofoceangen00murr Year: 1912 PHYSICAL OCEANOGRAPHY 253 but when the red rays, for instance, are cut off, a piece of red paper will look black. The usual method of studying the transparency of the water Transparency is to lower a large white disc, noting the depth at which it ofea-water. disappears from view. The degree of transparency is found to vary greatly, for in the clear dark-blue water in the middle of the ocean near the tropics the white disc can sometimes be seen as far down as 50 metres below the surface, or even more, while in those places where rivers bring down large quantities of detritus from the land the disc may occasionally be invisible a couple of metres beneath the surface. The enormous quantities of small plankton organisms inhabiting the upper layers may also render the water relatively opaque. The penetration of light thus varies according to circumstances, but few direct observations of the light-intensity have as yet been made. It would be of the greatest interest to know the amount of light at different depths in different seas, and thereby gain a better understanding of the conditions of life, for instance, as regards the development of the plankton, as the small plankton algae need light for the processes of assimilation. Sea-water normally contains oxygen, nitrogen (with argon). Gases in the and carbonic acid. These gases are absorbed at the surface • from the atmosphere, and are carried by currents even into the deepest parts of the ocean in varying amounts. A study of these variations is of considerable interest, and may be briefly dealt with here, although no gas-analyses were made during the 'Michael Sars ' Atlantic Expedition. There are several good methods of analysis. For the three gase
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Keywords: 1900, 1910, 1912, _michael_sars_north_atlantic_deep_sea_expedition_191, appell_f_jakob_johan_adolf_1857_, archive, book, bookauthor, bookcentury, bookdecade, bookpublisher, booksubject, bookyear, drawing, gran_h_h_haakon_hasberg_1870_, helland_hansen_bj_rn_1877_, historical, history, illustration, image, london_macmillan, murray_john_sir_1841_1914, north_atlantic_ocean, oceanography, page, picture, print, reference, vintage
