![]() In fact, the Quran also has the right idea: sea water and river water simply cannot mix. Although the sea is large, it cannot take over the river - the source of human fresh water. As the Quran of Muslims said that river water - sea water cannot mix, so the god created a boundary between river water and sea water to save people. In the past, many cultures explained, the cause of this phenomenon related to spirituality. The water area on the left is river water and the right is sea water. Their intersection created this beautiful scene.īut why are sea water and river water not merging, but forming such a strange boundary? ![]() However, rare places have a special separation like the Mississippi River area. Theoretically, it could happen in every ocean in the world, in the "Estuary" areas - where the river flows and flows into the sea. This "Split Sea" phenomenon video was recorded in Mississippi (USA). If you want to see more clearly this beautiful scene, please watch the video below. The split sea surface is recorded in Mississippi. It can be dangerous, violent with unbearable strength, but sometimes beautiful, brilliant and magnificent, like the phenomenon in the picture below. This work was financed by the interdisciplinary call for tenders 80|Prime 2019 (OFHYS project) and by the CNRS’ Mission for Interdisciplinarity.Every ocean in the world has a number of areas where the sea surface has been divided into two different water colors. Reference: “The dual nature of the dead-water phenomenology: Nansen versus Ekman wave-making drags” by Johan Fourdrinoy, Julien Dambrine, Madalina Petcu, Morgan Pierre and Germain Rousseaux, 8 July 2020, Proceedings of the National Academy of Sciences. Might the Bay of Actium, which has all the characteristics of a fjord, have trapped the Queen of Egypt’s fleet in dead water? So now we have another hypothesis to explain this resounding defeat, that in antiquity was attributed to remoras, ‘suckerfish’ attached to their hulls, as the legend goes. This work is part of a major project investigating why, during the Battle of Actium (31 BC), Cleopatra’s large ships lost when they faced Octavian’s weaker vessels. They have shown that the Ekman oscillating regime is only temporary: the ship ends up escaping and reaches the constant Nansen speed. The scientists have also reconciled the observations of both Nansen and Ekman. This work showed that these speed variations are due to the generation of specific waves that act as an undulating conveyor belt on which the ship moves back and forth. They used a mathematical classification of different internal waves and analysis of experimental images at the sub-pixel scale, a first. Physicists, fluid mechanics experts, and mathematicians at the CNRS’ Institut Pprime and the Laboratoire de Mathématiques et Applications (CNRS/Université de Poitiers) have attempted to solve this mystery. The second, Ekman wave-making drag, is characterized by speed oscillations in the trapped boat. The first, Nansen wave-making drag, causes a constant, abnormally low speed. It denotes two drag phenomena observed by scientists. This phenomenon, called dead water, is seen in all seas and oceans where waters of different densities (because of salinity or temperature) mix. In 1904, the Swedish physicist and oceanographer Vagn Walfrid Ekman showed in a laboratory that waves formed under the surface at the interface between the saltwater and freshwater layers that form the upper portion of this area of the Arctic Ocean interact with the ship, generating drag. In 1893, the Norwegian explorer Fridtjof Nansen experienced a strange phenomenon when he was traveling north of Siberia: his ship was slowed by a mysterious force and he could barely maneuver, let alone pick up normal speed. ![]() This work was published recently in Proceedings of the National Academy of Sciences (PNAS). An interdisciplinary team from the CNRS and the University of Poitiers has explained this phenomenon for the first time: the speed changes in ships trapped in dead water are due to waves that act like an undulating conveyor belt on which the boats move back and forth. What makes ships mysteriously slow down or even stop as they travel, even though their engines are working properly? This was first observed in 1893 and was described experimentally in 1904 without all the secrets of this “dead water” being understood. Dead water, present in all seas and oceans, occurs when waters of varying densities, due to differences in salinity or temperature, intermingle.
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