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Sigma-t
Sigma-t is a quantity used in oceanography to measure the density of seawater Seawater, or sea water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has approximat ... at a given temperature. σT is defined as ρ(S,T)-1000 kg m−3, where ρ(S,T) is the density of a sample of seawater at temperature T and salinity S, measured in kg m−3, at standard atmospheric pressure. For example, a water sample with a density of 1.027 g/cm3 has a σT value of 27. References {{reflist, 28em See also * Density of saltwater and ice Units of density ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oceanography
Oceanography (), also known as oceanology, sea science, ocean science, and marine science, is the scientific study of the ocean, including its physics, chemistry, biology, and geology. It is an Earth science, which covers a wide range of topics, including ocean currents, waves, and geophysical fluid dynamics; fluxes of various chemical substances and physical properties within the ocean and across its boundaries; ecosystem dynamics; and plate tectonics and seabed geology. Oceanographers draw upon a wide range of disciplines to deepen their understanding of the world’s oceans, incorporating insights from astronomy, biology, chemistry, geography, geology, hydrology, meteorology and physics. History Early history Humans first acquired knowledge of the waves and currents of the seas and oceans in pre-historic times. Observations on tides were recorded by Aristotle and Strabo in 384–322 BC. Early exploration of the oceans was primarily for cartography and mainly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Density
Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be used: \rho = \frac, where ''ρ'' is the density, ''m'' is the mass, and ''V'' is the volume. In some cases (for instance, in the United States oil and gas industry), density is loosely defined as its weight per unit volume, although this is scientifically inaccurate this quantity is more specifically called specific weight. For a pure substance, the density is equal to its mass concentration. Different materials usually have different densities, and density may be relevant to buoyancy, purity and packaging. Osmium is the densest known element at standard conditions for temperature and pressure. To simplify comparisons of density across different systems of units, it is sometimes replaced by the dimensionless quantity "relative den ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seawater
Seawater, or sea water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has approximately of dissolved salts (predominantly sodium () and chloride () ions). The average density at the surface is 1.025 kg/L. Seawater is denser than both fresh water and pure water (density 1.0 kg/L at ) because the dissolved salts increase the mass by a larger proportion than the volume. The freezing point of seawater decreases as salt concentration increases. At typical salinity, it freezes at about . The coldest seawater still in the liquid state ever recorded was found in 2010, in a stream under an Antarctic glacier: the measured temperature was . Seawater pH is typically limited to a range between 7.5 and 8.4. However, there is no universally accepted reference pH-scale for seawater and the difference between measuremen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kilogram Per Cubic Metre
The kilogram per cubic metre (symbol: kg·m−3, or kg/m3) is the unit of density in the International System of Units (SI). It is defined by dividing the SI unit of mass, the kilogram, by the SI unit of volume, the cubic metre. Conversions *1 kg/m3 = 1 g/ L (exactly) *1 kg/m3 = 0.001 g/cm3 (exactly) *1 kg/m3 ≈ 0.06243 lb/ ft3 (approximately) *1 kg/m3 ≈ 0.1335 oz/ US gal (approximately) *1 kg/m3 ≈ 0.1604 oz/ imp gal (approximately) *1 g/cm3 = 1000 kg/m3 (exactly) *1 lb/ft3 ≈ 16.02 kg/m3 (approximately) *1 oz/(US gal) ≈ 7.489 kg/m3 (approximately) *1 oz/(imp gal) ≈ 6.236 kg/m3 (approximately) Relation to other measures The density of water is about 1000 kg/m3 or 1 g/cm3, because the size of the gram was originally based on the mass of a cubic centimetre of water. In chemistry, g/cm3 is more commonly used. See also * Gram per cubic centimetre The gram per cubic centimetre is a unit of density in International System ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water (molecule)
Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent). It is vital for all known forms of life, despite not providing food energy or organic micronutrients. Its chemical formula, , indicates that each of its molecules contains one oxygen and two hydrogen atoms, connected by covalent bonds. The hydrogen atoms are attached to the oxygen atom at an angle of 104.45°. In liquid form, is also called "water" at standard temperature and pressure. Because Earth's environment is relatively close to water's triple point, water exists on Earth as a solid, a liquid, and a gas. It forms precipitation in the form of rain and aerosols in the form of fog. Clouds consist of suspended droplets of water and ice, its solid state. When finely divided, crystalline ice ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
