|
Dead Water
Dead water is the nautical term for a phenomenon which can occur when there is strong vertical density stratification due to salinity or temperature or both. It is common where a layer of fresh or brackish water rests on top of denser salt water, without the two layers mixing. The phenomenon is frequently, but not exclusively, observed in fjords where glacier runoff flows into salt water without much mixing. The phenomenon is a result of energy producing internal waves that have an effect on the vessel. The effect can also be found at density boundaries between sub surface layers. In the better known surface phenomenon a ship traveling in a fresh water layer with a depth approximately equal to the vessel's draft will expend energy creating and maintaining internal waves between the layers. The vessel may be hard to maneuver or can even slow down almost to a standstill and "stick". An increase in speed by a few knots can overcome the effect. Experiments have shown the effect can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Castro Battle Of Actium
Castro is a Romance language word that originally derived from Latin ''castrum'', a pre-Roman military camp or fortification (cf: Greek: ''kastron''; Proto-Celtic:''*Kassrik;'' br, kaer, *kastro). The English-language equivalent is '' chester''. It may refer to: People * Castro (surname), a surname (including a list of people with the name) ** José Antonio Castro (1808–1860) was a Mexican Californio politician, statesman, and general who served as interim Governor of Alta California and later Governor of Baja California. ** Julián Castro (Venezuelan politician) (1810–1875) a Venezuelan military officer and President of Venezuela between 1858 and 1859 ** Fidel Castro (1926–2016), dictator of Cuba, former First Secretary of the Communist Party of Cuba ** Raúl Castro (b. 1931), younger brother of Fidel Castro, former First Secretary of the Communist Party of Cuba ** Xiomara Castro (b. 1959), president of Honduras and wife of former Honduran president Manuel Zelaya * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Institut Pprime
Institut Pprime (sometimes written ''Institut P) is a CNRS laboratory created in 2010 and based in Poitiers, France. Presentation The institute depends from the University of Poitiers, ENSI Poitiers and Ensma and has the UPR number 3346. It is the second-largest laboratory from engineering science in France with 572 people working for it in 2014. , Pprime , April the 2nd 2014 It has locations in both campus of Poitiers and Futuroscope. It is currently led by Yves Gervais since 2014 after Jean-Paul Bonnet. The laboratory is sub-divided in three departments: * Physics and Mechanics of Materials * Fluids, Thermal and Combustion Sciences * Mechanics, Structures and Complex Systems It is the merger of six previous laboratories which was: LCD [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nautical Terminology
This glossary of nautical terms is an alphabetical listing of terms and expressions connected with ships, shipping, seamanship and navigation on water (mostly though not necessarily on the sea). Some remain current, while many date from the 17th to 19th centuries. The word nautical derives from the Latin ''nauticus'', from Greek ''nautikos'', from ''nautēs'': "sailor", from ''naus'': "ship". Further information on nautical terminology may also be found at Nautical metaphors in English, and additional military terms are listed in the Multiservice tactical brevity code article. Terms used in other fields associated with bodies of water can be found at Glossary of fishery terms, Glossary of underwater diving terminology, Glossary of rowing terms, and Glossary of meteorology. This glossary is split into two articles: * terms starting with the letters A to L are at Glossary of nautical terms (A-L) * terms starting with the letters M to Z are at Glossary of nautical terms (M-Z). __ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shelf Ice
Shelf ice is ice that forms when a portion of a lake surface freezes. It is often then washed upon the shore. The phenomenon is common within the Great Lakes. Formation Shelf ice forms from float ice. Float ice is like drift ice, but seldom becomes large enough to support humans or large animals. The cold temperatures freeze small areas of the open lake, forming float ice. Similar ice will form along the shoreline when the lake is calm. Over time, the ice will build up from continued freezing on the open lake and from snow accumulation on the surface. The surface of the Great Lake seldom remains calm enough for the entire surface to freeze. However, the smaller lakes, Lake St. Clair, Lake Erie, and Lake Ontario will freeze over more often than the larger upper lakes. The wind pushes the float ice and creates waves which also move the ice. Over time, the ice will accumulate on the leeward shores of the lake. Like sand, which is moved by the wind and the waves, the ice ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea Ice
Sea ice arises as seawater freezes. Because ice is less dense than water, it floats on the ocean's surface (as does fresh water ice, which has an even lower density). Sea ice covers about 7% of the Earth's surface and about 12% of the world's oceans. Much of the world's sea ice is enclosed within the polar ice packs in the Earth's polar regions: the Arctic ice pack of the Arctic Ocean and the Antarctic ice pack of the Southern Ocean. Polar packs undergo a significant yearly cycling in surface extent, a natural process upon which depends the Arctic ecology, including the ocean's ecosystems. Due to the action of winds, currents and temperature fluctuations, sea ice is very dynamic, leading to a wide variety of ice types and features. Sea ice may be contrasted with icebergs, which are chunks of ice shelves or glaciers that calve into the ocean. Depending on location, sea ice expanses may also incorporate icebergs. General features and dynamics Sea ice does not simply grow and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polynya
A polynya () is an area of open water surrounded by sea ice. It is now used as a geographical term for an area of unfrozen seawater within otherwise contiguous pack ice or fast ice. It is a loanword from the Russian полынья (), which refers to a natural ice hole and was adopted in the 19th century by polar explorers to describe navigable portions of the sea. There are two main types of polynyas: coastal polynyas, which can be found year-round near the Antarctic and Arctic coasts and are mainly created by strong winds pushing the ice away from the coast, and mid-sea or open-ocean polynyas, which may be found more sporadically in the middle of ice pack in certain locations, especially around Antarctica. These locations are generally preconditioned by certain oceanic dynamics. One of the most famous mid-sea polynyas is the Weddell Polynya, also known as the Maud Rise Polynya, which occurs in the Lazarev Sea over the Maud Rise seamount. It was first spotted in September 197 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arctic Ice Pack
The Arctic ice pack is the sea ice cover of the Arctic Ocean and its vicinity. The Arctic ice pack undergoes a regular seasonal cycle in which ice melts in spring and summer, reaches a minimum around mid-September, then increases during fall and winter. Summer ice cover in the Arctic is about 50% of winter cover. Some of the ice survives from one year to the next. Currently, 28% of Arctic basin sea ice is multi-year ice, thicker than seasonal ice: up to thick over large areas, with ridges up to thick. The regular seasonal cycle there has been an underlying trend of declining sea ice in the Arctic in recent decades as well. Climatic importance Energy balance effects Sea ice has an important effect on the heat balance of the polar oceans, since it insulates the (relatively) warm ocean from the much colder air above, thus reducing heat loss from the oceans. Sea ice is highly reflective of solar radiation, reflecting about 60% of incoming solar radiation when bare and abou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polar Ice Cap
A polar ice cap or polar cap is a high-latitude region of a planet, dwarf planet, or natural satellite that is covered in ice. There are no requirements with respect to size or composition for a body of ice to be termed a polar ice cap, nor any geological requirement for it to be over land, but only that it must be a body of solid phase matter in the polar region. This causes the term "polar ice cap" to be something of a misnomer, as the term ice cap itself is applied more narrowly to bodies that are over land, and cover less than 50,000 km2: larger bodies are referred to as ice sheets. The composition of the ice will vary. For example, Earth's polar caps are mainly water ice, whereas Mars's polar ice caps are a mixture of solid carbon dioxide and water ice. Polar ice caps form because high-latitude regions receive less energy in the form of solar radiation from the Sun than equatorial regions, resulting in lower surface temperatures. Earth's polar caps have changed d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nansen's Fram Expedition
Nansen's ''Fram'' expedition of 1893–1896 was an attempt by the Norwegian explorer Fridtjof Nansen to reach the geographical North Pole by harnessing the natural east–west current of the Arctic Ocean. In the face of much discouragement from other polar explorers, Nansen took his ship ''Fram'' to the New Siberian Islands in the eastern Arctic Ocean, froze her into the pack ice, and waited for the drift to carry her towards the pole. Impatient with the slow speed and erratic character of the drift, after 18 months Nansen and a chosen companion, Hjalmar Johansen, left the ship with a team of Samoyed dogs and sledges and made for the pole. They did not reach it, but they achieved a record Farthest North latitude of 86°13.6′N before a long retreat over ice and water to reach safety in Franz Josef Land. Meanwhile, ''Fram'' continued to drift westward, finally emerging in the North Atlantic Ocean. The idea for the expedition had arisen after items from the American vessel ''Je ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internal Wave
Internal waves are gravity waves that oscillate within a fluid medium, rather than on its surface. To exist, the fluid must be stratified: the density must change (continuously or discontinuously) with depth/height due to changes, for example, in temperature and/or salinity. If the density changes over a small vertical distance (as in the case of the thermocline in lakes and oceans or an atmospheric inversion), the waves propagate horizontally like surface waves, but do so at slower speeds as determined by the density difference of the fluid below and above the interface. If the density changes continuously, the waves can propagate vertically as well as horizontally through the fluid. Internal waves, also called internal gravity waves, go by many other names depending upon the fluid stratification, generation mechanism, amplitude, and influence of external forces. If propagating horizontally along an interface where the density rapidly decreases with height, they are specifically ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iceberg
An iceberg is a piece of freshwater ice more than 15 m long that has broken off a glacier or an ice shelf and is floating freely in open (salt) water. Smaller chunks of floating glacially-derived ice are called "growlers" or "bergy bits". The sinking of the ''Titanic'' in 1912 led to the formation of the International Ice Patrol in 1914. Much of an iceberg is below the surface, which led to the expression "tip of the iceberg" to illustrate a small part of a larger unseen issue. Icebergs are considered a serious maritime hazard. Icebergs vary considerably in size and shape. Icebergs that calve from glaciers in Greenland are often irregularly shaped while Antarctic ice shelves often produce large tabular (table top) icebergs. The largest iceberg in recent history (2000), named B-15, measured nearly 300 km × 40 km. The largest iceberg on record was an Antarctic tabular iceberg of over [] sighted west of Scott Island, in the South Pacific Ocean, by the USS Glacier ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Drift
Sea ice arises as seawater freezes. Because ice is less dense than water, it floats on the ocean's surface (as does fresh water ice, which has an even lower density). Sea ice covers about 7% of the Earth's surface and about 12% of the world's oceans. Much of the world's sea ice is enclosed within the polar ice packs in the Earth's polar regions: the Arctic ice pack of the Arctic Ocean and the Antarctic ice pack of the Southern Ocean. Polar packs undergo a significant yearly cycling in surface extent, a natural process upon which depends the Arctic ecology, including the ocean's ecosystems. Due to the action of winds, currents and temperature fluctuations, sea ice is very dynamic, leading to a wide variety of ice types and features. Sea ice may be contrasted with icebergs, which are chunks of ice shelves or glaciers that calve into the ocean. Depending on location, sea ice expanses may also incorporate icebergs. General features and dynamics Sea ice does not simply grow and me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.png "Click for more on -> Nautical Terminology")
