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Mbar
The bar is a metric unit of pressure defined as 100,000 Pa (100 kPa), though not part of the International System of Units (SI). A pressure of 1 bar is slightly less than the current average atmospheric pressure on Earth at sea level (approximately 1.013 bar). By the barometric formula, 1 bar is roughly the atmospheric pressure on Earth at an altitude of 111 metres at 15 °C. The bar and the millibar were introduced by the Norwegian meteorologist Vilhelm Bjerknes, who was a founder of the modern practice of weather forecasting, with the bar defined as one megadyne per square centimetre. The SI brochure, despite previously mentioning the bar, now omits any mention of it.. The bar has been legally recognised in countries of the European Union since 2004.British Standard BS 350:2004 ''Conversion Factors for Units''. The US National Institute of Standards and Technology (NIST) deprecates its use except for "limited use in meteorology" and lists it a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pressure Measurement
Pressure measurement is the measurement of an applied force by a fluid (liquid or gas) on a surface. Pressure is typically measured in units of force per unit of surface area. Many techniques have been developed for the measurement of pressure and vacuum. Instruments used to measure and display pressure mechanically are called pressure gauges, vacuum gauges or compound gauges (vacuum & pressure). The widely used Bourdon gauge is a mechanical device, which both measures and indicates and is probably the best known type of gauge. A vacuum gauge is used to measure pressures lower than the ambient atmospheric pressure, which is set as the zero point, in negative values (for instance, −1 bar or −760 mmHg equals total vacuum). Most gauges measure pressure relative to atmospheric pressure as the zero point, so this form of reading is simply referred to as "gauge pressure". However, anything greater than total vacuum is technically a form of pressure. For very low pres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atmospheric Pressure
Atmospheric pressure, also known as air pressure or barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1,013.25 millibars, 760 mm Hg, 29.9212 inchesHg, or 14.696 psi.International Civil Aviation Organization. ''Manual of the ICAO Standard Atmosphere'', Doc 7488-CD, Third Edition, 1993. . The atm unit is roughly equivalent to the mean sea-level atmospheric pressure on Earth; that is, the Earth's atmospheric pressure at sea level is approximately 1 atm. In most circumstances, atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point. As elevation increases, there is less overlying atmospheric mass, so atmospheric pressure decreases with increasing elevation. Because the atmosphere is thin relative to the Earth's radius—especially the dense atmospheric layer at low altitu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weather Forecasting
Weather forecasting or weather prediction is the application of science and technology forecasting, to predict the conditions of the Earth's atmosphere, atmosphere for a given location and time. People have attempted to predict the weather informally for thousands of years and formally since the 19th century. Weather forecasts are made by collecting quantitative data about the current state of the atmosphere, land, and ocean and using meteorology to project how the atmosphere will change at a given place. Once calculated manually based mainly upon changes in atmospheric pressure, barometric pressure, current weather conditions, and sky conditions or cloud cover, weather forecasting now relies on numerical weather prediction, computer-based models that take many atmospheric factors into account. Human input is still required to pick the best possible model to base the forecast upon, which involves pattern recognition skills, teleconnections, knowledge of model performance, and kn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atmospheric Pressure
Atmospheric pressure, also known as air pressure or barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1,013.25 millibars, 760 mm Hg, 29.9212 inchesHg, or 14.696 psi.International Civil Aviation Organization. ''Manual of the ICAO Standard Atmosphere'', Doc 7488-CD, Third Edition, 1993. . The atm unit is roughly equivalent to the mean sea-level atmospheric pressure on Earth; that is, the Earth's atmospheric pressure at sea level is approximately 1 atm. In most circumstances, atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point. As elevation increases, there is less overlying atmospheric mass, so atmospheric pressure decreases with increasing elevation. Because the atmosphere is thin relative to the Earth's radius—especially the dense atmospheric layer at low altitu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pressure
Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and even by industry. Further, both spellings are often used ''within'' a particular industry or country. Industries in British English-speaking countries typically use the "gauge" spelling. is the pressure relative to the ambient pressure. Various #Units, units are used to express pressure. Some of these derive from a unit of force divided by a unit of area; the International System of Units, SI unit of pressure, the Pascal (unit), pascal (Pa), for example, is one newton (unit), newton per square metre (N/m2); similarly, the Pound (force), pound-force per square inch (Pound per square inch, psi, symbol lbf/in2) is the traditional unit of pressure in the imperial units, imperial and United States customary units, US customary systems. Pressure ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pascal (unit)
The pascal (symbol: Pa) is the unit of pressure in the International System of Units (SI). It is also used to quantify internal pressure, stress, Young's modulus, and ultimate tensile strength. The unit, named after Blaise Pascal, is an SI coherent derived unit defined as one newton per square metre (N/m2). It is also equivalent to 10 barye (10 Ba) in the CGS system. Common multiple units of the pascal are the hectopascal (1 hPa = 100 Pa), which is equal to one millibar, and the kilopascal (1 kPa = 1000 Pa), which is equal to one centibar. The unit of measurement called '' standard atmosphere (atm)'' is defined as . Meteorological observations typically report atmospheric pressure in hectopascals per the recommendation of the World Meteorological Organization, thus a standard atmosphere (atm) or typical sea-level air pressure is about 1013 hPa. Reports in the United States typically use inches of mercury or millibars (hectopascals). In Cana ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Astronomical Union
The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and development through global cooperation. It was founded on 28 July 1919 in Brussels, Belgium and is based in Paris, France. The IAU is composed of individual members, who include both professional astronomers and junior scientists, and national members, such as professional associations, national societies, or academic institutions. Individual members are organised into divisions, committees, and working groups centered on particular subdisciplines, subjects, or initiatives. the Union had 85 national members and 12,734 individual members, spanning 90 countries and territories. Among the key activities of the IAU is serving as a forum for scientific conferences. It sponsors nine annual symposia and holds a triannual General Assembly that sets policy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient Greek
Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek Dark Ages, Dark Ages (), the Archaic Greece, Archaic or Homeric Greek, Homeric period (), and the Classical Greece, Classical period (). Ancient Greek was the language of Homer and of fifth-century Athens, fifth-century Athenian historians, playwrights, and Ancient Greek philosophy, philosophers. It has contributed many words to English vocabulary and has been a standard subject of study in educational institutions of the Western world since the Renaissance. This article primarily contains information about the Homeric Greek, Epic and Classical periods of the language, which are the best-attested periods and considered most typical of Ancient Greek. From the Hellenistic period (), Ancient Greek was followed by Koine Greek, which is regar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Usage
The usage of a language is the ways in which its written and spoken variations are routinely employed by its speakers; that is, it refers to "the collective habits of a language's native speakers", as opposed to idealized models of how a language works (or should work) in the abstract. For instance, Fowler characterized usage as "the way in which a word or phrase is normally and correctly used" and as the "points of grammar, syntax, style, and the choice of words." In everyday usage, language is used differently, depending on the situation and individual. Individual language users can shape language structures and language usage based on their community. In the descriptive tradition of language analysis, by way of contrast, "correct" tends to mean functionally adequate for the purposes of the speaker or writer using it, and adequately idiomatic to be accepted by the listener or reader; usage is also, however, a concern for the prescriptive tradition, for which "correctness" i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British Standard
British Standards (BS) are the standards produced by the BSI Group which is incorporated under a royal charter and which is formally designated as the national standards body (NSB) for the UK. The BSI Group produces British Standards under the authority of the charter, which lays down as one of the BSI's objectives to: Formally, as stated in a 2002 memorandum of understanding between the BSI and the United Kingdom Government, British Standards are defined as: Products and services which BSI certifies as having met the requirements of specific standards within designated schemes are awarded the Kitemark. History BSI Group began in 1901 as the ''Engineering Standards Committee'', led by James Mansergh, to standardize the number and type of steel sections, in order to make British manufacturers more efficient and competitive. Over time the standards developed to cover many aspects of tangible engineering, and then engineering methodologies including quality systems, sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weight
In science and engineering, the weight of an object is a quantity associated with the gravitational force exerted on the object by other objects in its environment, although there is some variation and debate as to the exact definition. Some standard textbooks define weight as a Euclidean vector, vector quantity, the gravitational force acting on the object. Others define weight as a scalar quantity, the magnitude of the gravitational force. Yet others define it as the magnitude of the reaction (physics), reaction force exerted on a body by mechanisms that counteract the effects of gravity: the weight is the quantity that is measured by, for example, a spring scale. Thus, in a state of free fall, the weight would be zero. In this sense of weight, terrestrial objects can be weightless: so if one ignores Drag (physics), air resistance, one could say the legendary apple falling from the tree, on its way to meet the ground near Isaac Newton, was weightless. The unit of measurement fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barye
The barye (symbol: Ba), or sometimes barad, barrie, bary, baryd, baryed, or barie, is the centimetre–gram–second (CGS) unit of pressure. It is equal to 1 dyne per square centimetre. : = = = = = See also *Pascal (unit) *International System of Units The International System of Units, internationally known by the abbreviation SI (from French ), is the modern form of the metric system and the world's most widely used system of measurement. It is the only system of measurement with official s ... References Centimetre–gram–second system of units Units of pressure {{measurement-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
