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GENERAL CAUSES OF CURRENTS. 57 BOOK* II.—CUKKENTS. CHAPTER VII. GREAT MOVEMENTS OF THE SEA.—GENERAL CAUSES OF CURRENTS.—THE FIVE OCEANIC RIVERS. Currents, that is to say, the real movements of the sea, much less visible to the eye thanfthe apparent displacements which constitute the waves, are notwithstanding of much greater importance in the economy of our planet. By their action enormous volumes of water, thousands of miles wide and hundreds of fathoms deep, move across the oceanic basins; the water of the polar seas is carried to equatorial regions, while these, on their side, send their waves in the direction of the poles. The liquid mass circulates incessantly, as if in a vast whirlpool, in every ocean of the globe, and we can follow in thought its gigantic circuit from the fields of ice to the warm atmosphere of the tropics. Currents are indeed only the ocean itself in motion, and by their action the waters of the sea are successively distributed over all parts of the globe. They are the windings of the great " salt river " of Homer, which rolls around the earth in one immense circuit. Every drop that has not already been raised in vapor to commence its long journey through clouds, mists, glaciers, and rivers, continually changes its place in the abysses of the sea; it descends to the bottom, or mounts to the surface; it moves from the equator to the pole, or from the pole to the equator; and thus traverses all parts of the ocean. It is to this continual displacement of its innumerable particles that the sea owes its uniformity in such a surprising manner, under all latitudes, as regards the appearance, composition, and saltness of its waters. Every difference of level which is produced on the liquid surface in consequence of prolonged winds, heavy rains, or very active evaporation, causes, as a necessary result, the formation of a current; for water, whether salt or fresh, ever seeks its level, and incessantly flows from the more elevated places toward the depressions. Every atmospheric variation has, for result, a displacement in one direction or another of the superficial water. But the great currents which flow with a regular movement around the basins of the ocean, between the polar and the equatorial zones, are determined by general causes acting at the same time on the entire planet. These causes are the sun's heat and the rotation of the earth on its axis. The equatorial basin, incessantly heated by the solar rays, loses a great
Title | The ocean, atmosphere, and life |
Creator | Reclus, Elisée |
Publisher | Harper |
Place of Publication | New York |
Date | 1873 |
Language | eng |
Type | Books/Pamphlets |
Title | 00000076 |
Type | Books/Pamphlets |
Transcript | GENERAL CAUSES OF CURRENTS. 57 BOOK* II.—CUKKENTS. CHAPTER VII. GREAT MOVEMENTS OF THE SEA.—GENERAL CAUSES OF CURRENTS.—THE FIVE OCEANIC RIVERS. Currents, that is to say, the real movements of the sea, much less visible to the eye thanfthe apparent displacements which constitute the waves, are notwithstanding of much greater importance in the economy of our planet. By their action enormous volumes of water, thousands of miles wide and hundreds of fathoms deep, move across the oceanic basins; the water of the polar seas is carried to equatorial regions, while these, on their side, send their waves in the direction of the poles. The liquid mass circulates incessantly, as if in a vast whirlpool, in every ocean of the globe, and we can follow in thought its gigantic circuit from the fields of ice to the warm atmosphere of the tropics. Currents are indeed only the ocean itself in motion, and by their action the waters of the sea are successively distributed over all parts of the globe. They are the windings of the great " salt river " of Homer, which rolls around the earth in one immense circuit. Every drop that has not already been raised in vapor to commence its long journey through clouds, mists, glaciers, and rivers, continually changes its place in the abysses of the sea; it descends to the bottom, or mounts to the surface; it moves from the equator to the pole, or from the pole to the equator; and thus traverses all parts of the ocean. It is to this continual displacement of its innumerable particles that the sea owes its uniformity in such a surprising manner, under all latitudes, as regards the appearance, composition, and saltness of its waters. Every difference of level which is produced on the liquid surface in consequence of prolonged winds, heavy rains, or very active evaporation, causes, as a necessary result, the formation of a current; for water, whether salt or fresh, ever seeks its level, and incessantly flows from the more elevated places toward the depressions. Every atmospheric variation has, for result, a displacement in one direction or another of the superficial water. But the great currents which flow with a regular movement around the basins of the ocean, between the polar and the equatorial zones, are determined by general causes acting at the same time on the entire planet. These causes are the sun's heat and the rotation of the earth on its axis. The equatorial basin, incessantly heated by the solar rays, loses a great |
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