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Frazil
Frazil ice is a collection of loose, randomly oriented ice crystals millimeter and sub-millimeter in size, with various shapes, e.g. elliptical disks, dendrites, needles and of an irregular nature. Frazil ice forms during the winter in open-water reaches of rivers as well as in lakes and reservoirs, where and when the water is in a turbulent state, which is, in turn, induced by the action of waves and currents. Turbulence causes the water column to become supercooled, as the heat exchange between the air and the water is such that the water temperature drops below its freezing point (in order of a few tenths of °C or less). The vertical mixing associated with that turbulence provides enough energy to overcome the crystals' buoyancy, thus keeping them from floating at the surface. Frazil ice also forms in oceans, where windy conditions, wave regimes and cold air also favor the establishment of a supercooled layer. Frazil ice can be found on the downwind side of leads, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frazil Ice In Yosemite Creek
Frazil ice is a collection of loose, randomly oriented ice crystals millimeter and sub-millimeter in size, with various shapes, e.g. elliptical disks, dendrites, needles and of an irregular nature. Frazil ice forms during the winter in open-water reaches of rivers as well as in lakes and reservoirs, where and when the water is in a turbulent state, which is, in turn, induced by the action of waves and currents. Turbulence causes the water column to become supercooled, as the heat exchange between the air and the water is such that the water temperature drops below its freezing point (in order of a few tenths of °C or less). The vertical mixing associated with that turbulence provides enough energy to overcome the crystals' buoyancy, thus keeping them from floating at the surface. Frazil ice also forms in oceans, where windy conditions, wave regimes and cold air also favor the establishment of a supercooled layer. Frazil ice can be found on the downwind side of leads, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grease Ice
Grease ice is a very thin, soupy layer of frazil crystals clumped together, which makes the ocean surface resemble an oil slick. Grease ice is the second stage in the formation of solid sea ice after ice floes and then frazil ice. New sea ice formation takes place throughout the winter in the Arctic. The first ice that forms in a polynya are loose ice crystals called frazil ice. If the level of turbulence is sufficient, the frazil ice will be mixed down into the upper layer and form a surface layer of grease ice. The term ‘grease ice’ follows World Meteorological Organization nomenclature. Grease ice differs from ‘slush’, where slush is similarly created by snow falling into the top layer of an ocean basin, river, or lake. The two terms are related due to the process of ice crystals being blown into a polynya which can be the initiation of the grease ice layer, given a minimum level of mixing and cooling of the ocean surface. Formation When the water surface begin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead (sea Ice)
A lead (, rhymes with "reed") is a large fracture within an expanse of sea ice, defining a linear area of open water that can be used for navigation purposes. Leads vary in width from meters to hundreds of meters. As is the case for polynyas (another sea ice feature involving open water), leads allow the direct interaction between the atmosphere and the ocean, and are important for Arctic sea ice ecology. Additionally it has been lately found that ice leads contribute significantly to the amount of mercury deposited onto surface and leaked into the ocean. If the air is cold enough (typically in the winter), the water within a lead quickly refreezes, such that in many cases, leads are partly or entirely covered by a thin layer of new ice.Weeks, W. F. (2010) ''On sea ice'' (Chap. 11). University of Alaska Press, Fairbanks, 664 p. Differences between leads and polynyas Unlike polynyas, which tend to occur, and remain, at a given location, leads are transient features that can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Jam
Ice jams occur when a topographic feature of the river causes floating river ice to accumulate and impede further progress downstream with the river current. Ice jams can significantly reduce the flow of a river and cause upstream flooding—sometimes called ice dams. Ice jam flooding can also occur downstream when the jam releases in an outburst flood. In either case, flooding can cause damage to structures on shore. Overview An ice blockage on a river is usually called an ''ice jam,'' but sometimes an ''ice dam''. An ice jam is an obstruction on a river formed by blocks of ice. Defined by the International Association of Hydraulic Research (IAHR) Working Group on River Ice Hydraulics an ice jam is a "stationary accumulation of fragmented ice or frazil that restricts flow" on a river or stream. The jam may effectively create a dam with an accumulation of anchor ice on the bottom of the river. On rivers the obstruction may be a change of width, structure, bend or decrease in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trash Rack
A trash rack (US) or debris screen is a wooden or metal structure, frequently supported by masonry, that prevents water-borne debris (such as logs, boats, animals, masses of cut waterweed, etc.) from entering the intake of a water mill, pumping station or water conveyance. This protects water wheels, penstocks, and sluice gates from destruction during floods. They are sometimes fitted to storm drain inflows and outflows to prevent debris from entering a natural watercourse. Other names used as trash screen (US) or debris grille. Trash racks composed of vertical wooden strakes separated by narrow gaps are very common and perform extremely poorly. Metal gratings are sturdier and can have narrower strakes, and angling the trash rack properly can allow some self-cleaning from the action of the water. Modern trash racks as used by hydroelectric plants can incorporate such advanced features as wedge-wire screens, the Coanda effect, and cleaning robots. In waterways with large amounts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rust
Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous iron(III) oxides (Fe2O3·nH2O) and iron(III) oxide-hydroxide (FeO(OH), Fe(OH)3), and is typically associated with the corrosion of refined iron. Given sufficient time, any iron mass, in the presence of water and oxygen, could eventually convert entirely to rust. Surface rust is commonly flaky and friable, and provides no passivational protection to the underlying iron, unlike the formation of patina on copper surfaces. ''Rusting'' is the common term for corrosion of elemental iron and its alloys such as steel. Many other metals undergo similar corrosion, but the resulting oxides are not commonly called "rust". Several forms of rust are distinguishable both visually and by spectroscopy, and form under different circumstances. Other forms of rust include the result of reactions between iron and chloride ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steel
Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant typically need an additional 11% chromium. Because of its high tensile strength and low cost, steel is used in buildings, infrastructure, tools, ships, trains, cars, machines, electrical appliances, weapons, and rockets. Iron is the base metal of steel. Depending on the temperature, it can take two crystalline forms (allotropic forms): body-centred cubic and face-centred cubic. The interaction of the allotropes of iron with the alloying elements, primarily carbon, gives steel and cast iron their range of unique properties. In pure iron, the crystal structure has relatively little resistance to the iron atoms slipping past one another, and so pure iron is quite ductile, or soft and easily formed. In steel, small amounts of carbon, other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plastic
Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptability, plus a wide range of other properties, such as being lightweight, durable, flexible, and inexpensive to produce, has led to its widespread use. Plastics typically are made through human industrial systems. Most modern plastics are derived from fossil fuel-based chemicals like natural gas or petroleum; however, recent industrial methods use variants made from renewable materials, such as corn or cotton derivatives. 9.2 billion tonnes of plastic are estimated to have been made between 1950 and 2017. More than half this plastic has been produced since 2004. In 2020, 400 million tonnes of plastic were produced. If global trends on plastic demand continue, it is estimated that by 2050 annual global plastic production will reach over 1, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tritium
Tritium ( or , ) or hydrogen-3 (symbol T or H) is a rare and radioactive isotope of hydrogen with half-life about 12 years. The nucleus of tritium (t, sometimes called a ''triton'') contains one proton and two neutrons, whereas the nucleus of the common isotope hydrogen-1 (''protium'') contains one proton and zero neutrons, and that of hydrogen-2 (''deuterium'') contains one proton and one neutron. Naturally occurring tritium is extremely rare on Earth. The atmosphere has only trace amounts, formed by the interaction of its gases with cosmic rays. It can be produced artificially by irradiating lithium metal or lithium-bearing ceramic pebbles in a nuclear reactor and is a low-abundance byproduct in normal operations of nuclear reactors. Tritium is used as the energy source in radioluminescent lights for watches, gun sights, numerous instruments and tools, and even novelty items such as self-illuminating key chains. It is used in a medical and scientific setting as a radioacti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adhesion
Adhesion is the tendency of dissimilar particles or surfaces to cling to one another ( cohesion refers to the tendency of similar or identical particles/surfaces to cling to one another). The forces that cause adhesion and cohesion can be divided into several types. The intermolecular forces responsible for the function of various kinds of stickers and sticky tape fall into the categories of chemical adhesion, dispersive adhesion, and diffusive adhesion. In addition to the cumulative magnitudes of these intermolecular forces, there are also certain emergent mechanical effects. Surface energy Surface energy is conventionally defined as the work that is required to build an area of a particular surface. Another way to view the surface energy is to relate it to the work required to cleave a bulk sample, creating two surfaces. If the new surfaces are identical, the surface energy γ of each surface is equal to half the work of cleavage, W: γ = (1/2)W11. If the surfac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dynamite
Dynamite is an explosive made of nitroglycerin, sorbents (such as powdered shells or clay), and Stabilizer (chemistry), stabilizers. It was invented by the Swedish people, Swedish chemist and engineer Alfred Nobel in Geesthacht, Northern Germany, and patented in 1867. It rapidly gained wide-scale use as a more robust alternative to gun powder, black powder. History Dynamite was invented by Swedish chemist Alfred Nobel in the 1860s and was the first safely manageable explosive stronger than black powder. Alfred Nobel's father, Immanuel Nobel, was an industrialist, engineer, and inventor. He built bridges and buildings in Stockholm and founded Sweden's first rubber factory. His construction work inspired him to research new methods of blasting rock that were more effective than black powder. After some bad business deals in Sweden, in 1838 Immanuel moved Nobel family, his family to Saint Petersburg, where Alfred and his brothers were educated privately under Swedish and Russi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Resistance Heater
Electric heating is a process in which electrical energy is converted directly to heat energy at around 100% efficiency, using rather cheap devices. Common applications include space heating, cooking, water heating and industrial processes. An electric heater is an electrical device that converts an electric current into heat. The heating element inside every electric heater is an electrical resistor, and works on the principle of Joule heating: an electric current passing through a resistor will convert that electrical energy into heat energy. Most modern electric heating devices use nichrome wire as the active element; the heating element, depicted on the right, uses nichrome wire supported by ceramic insulators. Alternatively, a heat pump can achieve around 300% efficiency for heating, or 3.0 Coefficient of performance, because it uses electric power only for transferring existing thermal energy from the surrounding area, mostly air. The heat pump uses an electric motor to dr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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