04-19-2022-2001 - Convection

 Convection (or convective heat transfer) is the transfer of heat from one place to another due to the movement of fluid. Although often discussed as a distinct method of heat transfer, convective heat transfer involves the combined processes of conduction (heat diffusion) and advection (heat transfer by bulk fluid flow). Convection is usually the dominant form of heat transfer in liquids and gases.

Note that this definition of convection is only applicable in Heat transfer and thermodynamic contexts. It should not to be confused with the dynamic fluid phenomenon of convection, which is typically referred to as Natural Convection in thermodynamic contexts in order to distinguish the two.

https://en.wikipedia.org/wiki/Convection_(heat_transfer)

In the field of physics, engineering, and earth sciences, advection is the transport of a substance or quantity by bulk motion of a fluid. The properties of that substance are carried with it. Generally the majority of the advected substance is a fluid. The properties that are carried with the advected substance are conserved properties such as energy. An example of advection is the transport of pollutants or silt in a river by bulk water flow downstream. Another commonly advected quantity is energy or enthalpy. Here the fluid may be any material that contains thermal energy, such as water or air. In general, any substance or conserved, extensive quantity can be advected by a fluid that can hold or contain the quantity or substance.

During advection, a fluid transports some conserved quantity or material via bulk motion. The fluid's motion is described mathematically as a vector field, and the transported material is described by a scalar field showing its distribution over space. Advection requires currents in the fluid, and so cannot happen in rigid solids. It does not include transport of substances by molecular diffusion.

Advection is sometimes confused with the more encompassing process of convection which is the combination of advective transport and diffusive transport.

In meteorology and physical oceanography, advection often refers to the transport of some property of the atmosphere or ocean, such as heat, humidity (see moisture) or salinity. Advection is important for the formation of orographic clouds and the precipitation of water from clouds, as part of the hydrological cycle.

https://en.wikipedia.org/wiki/Advection

Orography (from the Greek όρος, hill, γραφία, to write) is the study of the topographic relief of mountains,^[1] and can more broadly include hills, and any part of a region's elevated terrain.^[2] Orography (also known as oreography, orology or oreology) falls within the broader discipline of geomorphology.^[3]

https://en.wikipedia.org/wiki/Orography

Salinity (/səˈlɪnɪti/) is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal to ‰).

Salinity is an important factor in determining many aspects of the chemistry of natural waters and of biological processes within it, and is a thermodynamic state variable that, along with temperature and pressure, governs physical characteristics like the density and heat capacity of the water.

A contour line of constant salinity is called an isohaline, or sometimes isohale.

https://en.wikipedia.org/wiki/Salinity

Membrane bioreactor (MBR) is a combination of membrane process like microfiltration or ultrafiltration with a biological wastewater treatment process, the activated sludge process. It is now widely used for municipal and industrial wastewater treatment.^[1]

https://en.wikipedia.org/wiki/Membrane_bioreactor

Acid mine drainage, acid and metalliferous drainage (AMD), or acid rock drainage (ARD) is the outflow of acidic water from metal mines or coal mines.

https://en.wikipedia.org/wiki/Acid_mine_drainage

Anthracite, also known as hard coal, and black coal, is a hard, compact variety of coal that has a submetallic luster. It has the highest carbon content, the fewest impurities, and the highest energy density of all types of coal and is the highest ranking of coals.

Anthracite is the most metamorphosed type of coal (but still represents low-grade metamorphism),^[a] in which the carbon content is between 86% and 97%.^[1][3][4] The term is applied to those varieties of coal which do not give off tarry or other hydrocarbon vapours when heated below their point of ignition.^[5] Anthracite ignites with difficulty and burns with a short, blue, and smokeless flame.

Anthracite is categorised into standard grade, which is used mainly in power generation,^{[contradictory]} and high grade (HG) and ultra high grade (UHG), the principal uses of which are in the metallurgy sector. Anthracite accounts for about 1% of global coal reserves,^[6] and is mined in only a few countries around the world.

The Coal Region of northeastern Pennsylvania in the United States is home to the largest known deposits of anthracite coal in the world with an estimated reserve of seven billion short tons.^[7]China accounts for the majority of global production; other producers are Russia, Ukraine, North Korea, South Africa, Vietnam, the UK, Australia, Canada, and the United States. Total production in 2020 was 615 million tons.^[8]

Trace metal and semi-metal contamination[edit]

Many acid rock discharges also contain elevated levels of potentially toxic metals, especially nickel and copper with lower levels of a range of trace and semi-metal ions such as lead, arsenic, aluminium, and manganese. The elevated levels of heavy metals can only be dissolved in waters that have a low pH, as is found in the acidic waters produced by pyrite oxidation. In the coal belt around the south Wales valleys in the UK highly acidic nickel-rich discharges from coal stocking sites have proved to be particularly troublesome.^{[citation needed]}

https://en.wikipedia.org/wiki/Anthracite

hide v t e Wastewater
Sources and types	Acid mine drainage Ballast water Bathroom Blackwater (coal) Blackwater (waste) Boiler blowdown Brine Combined sewer Cooling tower Cooling water Fecal sludge Grey water Infiltration/Inflow Industrial wastewater Ion exchange Leachate Manure Papermaking Produced water Return flow Reverse osmosis Sanitary sewer Septage Sewage Sewage sludge Toilet Urban runoff
Quality indicators	Adsorbable organic halides Biochemical oxygen demand Chemical oxygen demand Coliform index Oxygen saturation Heavy metals pH Salinity Temperature Total dissolved solids Total suspended solids Turbidity Wastewater surveillance
Treatment options	Activated sludge Aerated lagoon Agricultural wastewater treatment API oil–water separator Carbon filtering Chlorination Clarifier Constructed wetland Decentralized wastewater system Extended aeration Facultative lagoon Fecal sludge management Filtration Imhoff tank Industrial wastewater treatment Ion exchange Membrane bioreactor Reverse osmosis Rotating biological contactor Secondary treatment Sedimentation Septic tank Settling basin Sewage sludge treatment Sewage treatment Sewer mining Stabilization pond Trickling filter Ultraviolet germicidal irradiation UASB Vermifilter Wastewater treatment plant
Disposal options	Combined sewer Evaporation pond Groundwater recharge Infiltration basin Injection well Irrigation Marine dumping Marine outfall Reclaimed water Sanitary sewer Septic drain field Sewage farm Storm drain Surface runoff Vacuum sewer
Category: Sewerage

Authority control: National libraries	Germany Israel United States

https://en.wikipedia.org/wiki/Salinity

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In continuum mechanics, vorticity is a pseudovector field that describes the local spinning motion of a continuum near some point (the tendency of something to rotate^[1]), as would be seen by an observer located at that point and traveling along with the flow. It is an important quantity in the dynamical theory of fluids and provides a convenient framework for understanding a variety of complex flow phenomena, such as the formation and motion of vortex rings.^[2][3]

Mathematically, the vorticity ${\displaystyle {\vec {\omega }}}$ is the curl of the flow velocity ${\displaystyle {\vec {u}}}$:^[4][3]

${\displaystyle {\vec {\omega }}\equiv \nabla \times {\vec {u}}\,,}$

where ${\displaystyle \nabla }$ is the del operator. Conceptually, ${\displaystyle {\vec {\omega }}}$ could be determined by marking parts of a continuum in a small neighborhood of the point in question, and watching their relative displacements as they move along the flow. The vorticity ${\displaystyle {\vec {\omega }}}$ would be twice the mean angular velocity vector of those particles relative to their center of mass, oriented according to the right-hand rule.

In a two-dimensional flow, ${\displaystyle {\vec {\omega }}}$ is always perpendicular to the plane of the flow, and can therefore be considered a scalar field.

https://en.wikipedia.org/wiki/Vorticity

Wind shear (or windshear), sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizontal wind shear. Vertical wind shear is a change in wind speed or direction with a change in altitude. Horizontal wind shear is a change in wind speed with a change in lateral position for a given altitude.^[1]

Wind shear is a microscale meteorological phenomenon occurring over a very small distance, but it can be associated with mesoscale or synoptic scale weather features such as squall lines and cold fronts. It is commonly observed near microbursts and downbursts caused by thunderstorms, fronts, areas of locally higher low-level winds referred to as low-level jets, near mountains, radiation inversions that occur due to clear skies and calm winds, buildings, wind turbines, and sailboats. Wind shear has significant effects on the control of an aircraft, and it has been the sole or a contributing cause of many aircraft accidents.

Sound movement through the atmosphere is affected by wind shear, which can bend the wave front, causing sounds to be heard where they normally would not, or vice versa. Strong vertical wind shear within the troposphere also inhibits tropical cyclone development but helps to organize individual thunderstorms into longer life cycles which can then produce severe weather. The thermal wind concept explains how differences in wind speed at different heights are dependent on horizontal temperature differences and explains the existence of the jet stream.^[2]

https://en.wikipedia.org/wiki/Wind_shear

In meteorology, convective available potential energy (commonly abbreviated as CAPE),^[1] is the integrated amount of work that the upward (positive) buoyancy force would perform on a given mass of air (called an air parcel) if it rose vertically through the entire atmosphere. Positive CAPE will cause the air parcel to rise, while negative CAPE will cause the air parcel to sink. Nonzero CAPE is an indicator of atmospheric instability in any given atmospheric sounding, a necessary condition for the development of cumulus and cumulonimbus clouds with attendant severe weather hazards.

https://en.wikipedia.org/wiki/Convective_available_potential_energy

In fluid dynamics, a barotropic fluid is a fluid whose density is a function of pressure only.^[1] The barotropic fluid is a useful model of fluid behavior in a wide variety of scientific fields, from meteorology to astrophysics.

The density of most liquids is nearly constant (isopycnic), so it can be stated that their densities vary only weakly with pressure and temperature. Water, which varies only a few percent with temperature and salinity, may be approximated as barotropic. In general, air is not barotropic, as it is a function of temperature and pressure; but, under certain circumstances, the barotropic assumption can be useful.

In astrophysics, barotropic fluids are important in the study of stellar interiors or of the interstellar medium. One common class of barotropic model used in astrophysics is a polytropic fluid. Typically, the barotropic assumption is not very realistic.

In meteorology, a barotropic atmosphere is one that for which the density of the air depends only on pressure, as a result isobaric surfaces (constant-pressure surfaces) are also constant-density surfaces. Such isobaric surfaces will also be isothermal surfaces, hence (from the thermal wind equation) the geostrophic wind will not vary with depth. Hence, the motions of a rotating barotropic air mass is strongly constrained. The tropics are more nearly barotropic than mid-latitudes because temperature is more nearly horizontally uniform in the tropics.

A barotropic flow is a generalization of a barotropic atmosphere. It is a flow in which the pressure is a function of the density only and vice versa. In other words, it is a flow in which isobaric surfaces are isopycnic surfaces and vice versa. One may have a barotropic flow of a non-barotropic fluid, but a barotropic fluid will always follow a barotropic flow. Examples include barotropic layers of the oceans, an isothermal ideal gas or an isentropic ideal gas.

A fluid which is not barotropic is baroclinic, i. e., pressure is not the only factor to determine density. For a barotropic fluid or a barotropic flow (such as a barotropic atmosphere), the baroclinic vector is zero.

https://en.wikipedia.org/wiki/Barotropic_fluid

An isopycnic surface is a surface of constant density inside a fluid. Isopycnic surfaces contrast with isobaric or isothermal surfaces, which describe surfaces of constant pressure and constant temperature respectively. Isopycnic surfaces are sometimes referred to as "iso-density" surfaces, although this is strictly incorrect. Isopycnic typically describes surfaces, not processes. Unless there is a flux of mass into or out of a control volume, a process which occurs at a constant density also occurs at a constant volume and is called an isochoric process and not an isopycnic process.

https://en.wikipedia.org/wiki/Isopycnic

In atmospheric thermodynamics, the virtual temperature (${\displaystyle T_{v}}$) of a moist air parcel is the temperature at which a theoretical dry air parcel would have a total pressure and density equal to the moist parcel of air.^[1] The virtual temperature of unsaturated moist air is always greater than the absolute air temperature, however, the existence of suspended cloud droplets reduces the virtual temperature.

Description[edit]

In atmospheric thermodynamic processes, it is often useful to assume air parcels behave approximately adiabatically, and approximately ideally. The specific gas constant for the standardized mass of one kilogram of a particular gas is variable, and described mathematically as

${\displaystyle R_{x}={\frac {R^{*}}{M_{x}}},}$

where ${\displaystyle R^{*}}$ is the molar gas constant, and ${\displaystyle M_{x}}$ is the apparent molar mass of gas ${\displaystyle x}$ in kilograms per mole. The apparent molar mass of a theoretical moist parcel in Earth's atmosphere can be defined in components of water vapor and dry air as

${\displaystyle M_{\text{air}}={\frac {e}{p}}M_{v}+{\frac {p_{d}}{p}}M_{d},}$

with ${\displaystyle e}$ being partial pressure of water, ${\displaystyle p_{d}}$ dry air pressure, and ${\displaystyle M_{v}}$ and ${\displaystyle M_{d}}$ representing the molar masses of water vapor and dry air respectively. The total pressure ${\displaystyle p}$ is described by Dalton's law of partial pressures:

${\displaystyle p=p_{d}+e.}$

https://en.wikipedia.org/wiki/Virtual_temperature

In physics, magnetic tension is a restoring force with units of force density that acts to straighten bent magnetic field lines. The force density (in SI) ${\displaystyle {\mathcal {J}}}$ exerted perpendicular to a magnetic field ${\displaystyle \mathbf {B} }$ can be expressed as

$${\displaystyle {\mathcal {J}}={\frac {\left(\mathbf {B} \cdot \nabla \right)\mathbf {B} }{\mu _{0}}}}$$

where ${\displaystyle \mu _{0}}$ is the vacuum permeability.

Magnetic tension forces also rely on vector current densities and their interaction with the magnetic field. Plotting magnetic tension along adjacent field lines can give a picture as to their divergence and convergence with respect to each other as well as current densities.

Magnetic tension is analogous to the restoring force of rubber bands.

https://en.wikipedia.org/wiki/Magnetic_tension

A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents,^{[1]: ch1 [2]} and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field.^{[1]: ch13 [3]} A permanent magnet's magnetic field pulls on ferromagnetic materials such as iron, and attracts or repels other magnets. In addition, a magnetic field that varies with location will exert a force on a range of non-magnetic materials by affecting the motion of their outer atomic electrons. Magnetic fields surround magnetized materials, and are created by electric currents such as those used in electromagnets, and by electric fields varying in time. Since both strength and direction of a magnetic field may vary with location, it is described mathematically by a function assigning a vector to each point of space, called a vector field.

In electromagnetics, the term "magnetic field" is used for two distinct but closely related vector fields denoted by the symbols B and H. In the International System of Units, H, magnetic field strength, is measured in the SI base units of ampere per meter (A/m).^[4] B, magnetic flux density, is measured in tesla (in SI base units: kilogram per second² per ampere),^[5] which is equivalent to newton per meter per ampere. H and B differ in how they account for magnetization. In a vacuum, the two fields are related through the vacuum permeability, ${\displaystyle \mathbf {B} /\mu _{0}=\mathbf {H} }$; but in a magnetized material, the terms differ by the material's magnetization at each point.

Magnetic fields are produced by moving electric charges and the intrinsic magnetic moments of elementary particles associated with a fundamental quantum property, their spin.^{[6][1]: ch1} Magnetic fields and electric fields are interrelated and are both components of the electromagnetic force, one of the four fundamental forces of nature.

Magnetic fields are used throughout modern technology, particularly in electrical engineering and electromechanics. Rotating magnetic fields are used in both electric motors and generators. The interaction of magnetic fields in electric devices such as transformers is conceptualized and investigated as magnetic circuits. Magnetic forces give information about the charge carriers in a material through the Hall effect. The Earth produces its own magnetic field, which shields the Earth's ozone layer from the solar wind and is important in navigation using a compass.

https://en.wikipedia.org/wiki/Magnetic_field#Magnetic_field_lines