|
Thermal Wind
In atmospheric science, the thermal wind is the vector difference between the geostrophic wind at upper altitudes minus that at lower altitudes in the atmosphere. It is the hypothetical vertical wind shear that would exist if the winds obey geostrophic balance in the horizontal, while pressure obeys hydrostatic balance in the vertical. The combination of these two force balances is called ''thermal wind balance'', a term generalizable also to more complicated horizontal flow balances such as gradient wind balance. Since the geostrophic wind at a given pressure level flows along geopotential height contours on a map, and the geopotential thickness of a pressure layer is proportional to virtual temperature, it follows that the thermal wind flows along thickness or temperature contours. For instance, the thermal wind associated with pole-to-equator temperature gradients is the primary physical explanation for the jet stream in the upper half of the troposphere, which is the at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jet Stream
Jet streams are fast flowing, narrow thermal wind, air currents in the Earth's Atmosphere of Earth, atmosphere. The main jet streams are located near the altitude of the tropopause and are westerly winds, flowing west to east around the globe. The northern hemisphere and the southern hemisphere each have a polar jet around their respective polar vortex at around above sea level and typically travelling at around although often considerably faster. Closer to the equator and somewhat higher and somewhat weaker is a subtropical jet. The northern polar jet flows over the middle to northern latitudes of North America, Europe, and Asia and their intervening oceans, while the southern hemisphere polar jet mostly circles Antarctica. Jet streams may start, stop, split into two or more parts, combine into one stream, or flow in various directions including opposite to the direction of the remainder of the jet. The El Niño–Southern Oscillation affects the location of the jet s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ernest Gold (meteorologist)
Ernest Gold (24 July 1881 – 30 January 1976) was a British meteorologist and Lieutenant-Colonel. Family and education Ernest Gold was born at Berkswell, near Coventry, Warwickshire, in 1881. His parents were John Gold, a tenant farmer, and Ellen Gold Peckett. He was educated at Coleshill Grammar School and Mason University College (which became the University of Birmingham). Gold then attended St John's College, Cambridge. He was awarded First Class Honours in the Cambridge Natural Sciences Tripos in 1903, graduating as Third Wrangler. Early career In June 1906, Gold was employed for a year at the Meteorological Office as Superintendent of Instruments. From 1907 to 1910 he was appointed the Schuster Reader in Dynamical Meteorology at the University of Cambridge. During this time he focused his research on radioactive equilibrium in the stratosphere and produced the first scientific explanation for isothermal conditions. In 1910 he returned to work at the Meteorolo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Backing And Veering
The back is the large posterior area of the human body, rising from the top of the buttocks to the back of the neck and the shoulders. Back may also refer to: People * Adam Back (born 1970), British cryptographer * Charles Back, South African winemaker * Chris Back (born 1950), Australian politician * Ernst Emil Alexander Back (1881–1959), German physicist * Frédéric Back (1924–2013), Canadian animator * George Back (1796–1878), British naval officer and explorer * Les Back (born 1962), English sociology professor and author * Natasja Crone Back (born 1971), Danish journalist * Neil Back (born 1969), English rugby player * Ralph-Johan Back, Finnish computer scientist * Rico Back (born 1954), Swiss-domiciled German businessman * Sven-Erik Bäck (1919–1984), Swedish composer * William Back (1856–1911), Australian cricketer Places * Back (crater), lunar crater * Back, Lewis, a village on the Isle of Lewis, Scotland * Back Bay (other), several places * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coriolis Parameter
The Coriolis frequency ''ƒ'', also called the Coriolis parameter or Coriolis coefficient, is equal to twice the rotation rate ''Ω'' of the Earth multiplied by the sine of the latitude \varphi. f = 2 \Omega \sin \varphi.\, The rotation rate of the Earth (''Ω'' = 7.2921 × 10−5 rad/s) can be calculated as 2''π'' / ''T'' radians per second, where ''T'' is the rotation period of the Earth which is one ''sidereal'' day (23 h 56 min 4.1 s). In the midlatitudes, the typical value for f is about 10−4 rad/s. Inertial oscillations on the surface of the Earth have this frequency. These oscillations are the result of the Coriolis effect. Explanation Consider a body (for example a fixed volume of atmosphere) moving along at a given latitude \varphi at velocity v in the Earth's rotating reference frame. In the local reference frame of the body, the vertical direction is parallel to the radial vector poi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geopotential
Geopotential (symbol ''W'') is the potential of the Earth's gravity field. It has SI units of square metre per square seconds (m2/s2). For convenience it is often defined as the of the potential energy per unit mass, so that the gravity vector is obtained as the gradient of the geopotential, without the negation. In addition to the actual potential (the geopotential), a theoretical normal potential (symbol ''U'') and their difference, the disturbing potential (), can also be defined. Concepts For geophysical applications, gravity is distinguished from gravitation. Gravity is defined as the resultant force of gravitation and the centrifugal force caused by the Earth's rotation. Likewise, the respective scalar potentials, gravitational potential and centrifugal potential, can be added to form an effective potential called the geopotential, W. The surfaces of constant geopotential or isosurfaces of the geopotential are called ''equigeopotential surfaces'' (sometimes a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gas Constant
The molar gas constant (also known as the gas constant, universal gas constant, or ideal gas constant) is denoted by the symbol or . It is the molar equivalent to the Boltzmann constant, expressed in units of energy per temperature increment per amount of substance, rather than energy per temperature increment per ''particle''. The constant is also a combination of the constants from Boyle's law, Charles's law, Avogadro's law, and Gay-Lussac's law. It is a physical constant that is featured in many fundamental equations in the physical sciences, such as the ideal gas law, the Arrhenius equation, and the Nernst equation. The gas constant is the constant of proportionality that relates the energy scale in physics to the temperature scale and the scale used for amount of substance. Thus, the value of the gas constant ultimately derives from historical decisions and accidents in the setting of units of energy, temperature and amount of substance. The Boltzmann constant a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypsometric Equation
The hypsometric equation, also known as the thickness equation, relates an atmospheric pressure ratio to the equivalent thickness of an atmospheric layer considering the layer mean of virtual temperature, gravity, and occasionally wind. It is derived from the hydrostatic equation and the ideal gas law. Formulation The hypsometric equation is expressed as: h = z_2 - z_1 = \frac \, \ln \left(\frac\right), where: *h = thickness of the layer /nowiki>, *z = geometric height /nowiki>, *R = specific gas constant for dry air, *\overline = mean virtual temperature in Kelvin /nowiki>, *g = gravitational acceleration /s2/nowiki>, *p = pressure Pa">Pascal_(unit).html" ;"title="/nowiki>Pascal (unit)">Pa/nowiki>. In meteorology, p_1 and p_2 are wikt:isobaric, isobaric surfaces. In radiosonde observation, the hypsometric equation can be used to compute the height of a pressure level given the height of a reference pressure level and the mean virtual temperature in between. Then, the newl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baroclinic
In fluid dynamics, the baroclinity (often called baroclinicity) of a stratified fluid is a measure of how misaligned the gradient of pressure is from the gradient of density in a fluid. In meteorology, a baroclinic flow is one in which the density depends on both temperature and pressure (the fully general case). A simpler case, barotropic flow, allows for density dependence only on pressure, so that the curl of the pressure-gradient force vanishes. Baroclinity is proportional to: :\nabla p \times \nabla \rho which is proportional to the sine of the angle between surfaces of constant pressure and surfaces of constant density. Thus, in a ''barotropic'' fluid (which is defined by zero baroclinity), these surfaces are parallel. In Earth's atmosphere, barotropic flow is a better approximation in the tropics, where density surfaces and pressure surfaces are both nearly level, whereas in higher latitudes the flow is more baroclinic. These midlatitude belts of high atmospheric ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barotropic Fluid
In fluid dynamics, a barotropic fluid is a fluid whose density is a function of pressure only. 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 onl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal Wind, Baroclinic & Barotropic Atmospheres
A thermal column (or thermal) is a rising mass of buoyant air, a convective current in the atmosphere, that transfers heat energy vertically. Thermals are created by the uneven heating of Earth's surface from solar radiation, and are an example of convection, specifically atmospheric convection. Thermals on Earth The Sun warms the ground, which in turn warms the air directly above. The warm air near the surface expands, becoming less dense than the surrounding air. The lighter air rises and cools due to its expansion in the lower pressure at higher altitudes. It stops rising when it has cooled to the same temperature, thus density, as the surrounding air. Associated with a thermal is a downward flow surrounding the thermal column. The downward-moving exterior is caused by colder air being displaced at the top of the thermal. The size and strength of thermals are influenced by the properties of the lower atmosphere (the ''troposphere''). When the air is cold, bubbles of warm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gravitational Force
Newton's law of universal gravitation describes gravity as a force by stating that every particle attracts every other particle in the universe with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between their centers of mass. Separated objects attract and are attracted as if all their mass were concentrated at their centers. The publication of the law has become known as the " first great unification", as it marked the unification of the previously described phenomena of gravity on Earth with known astronomical behaviors. This is a general physical law derived from empirical observations by what Isaac Newton called ''inductive reasoning''. It is a part of classical mechanics and was formulated in Newton's work ''Philosophiæ Naturalis Principia Mathematica'' (Latin for 'Mathematical Principles of Natural Philosophy' (the ''Principia'')), first published on 5 July 1687. The equation for universal gravitation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pressure-gradient Force
In fluid mechanics, the pressure-gradient force is the force that results when there is a difference in pressure across a surface. In general, a pressure is a force per unit area across a surface. A difference in pressure across a surface then implies a difference in force, which can result in an acceleration according to Newton's second law of motion, if there is no additional force to balance it. The resulting force is always directed from the region of higher-pressure to the region of lower-pressure. When a fluid is in an equilibrium state (i.e. there are no net forces, and no acceleration), the system is referred to as being in hydrostatic equilibrium. In the case of atmospheres, the pressure-gradient force is balanced by the gravitational force, maintaining hydrostatic equilibrium. In Earth's atmosphere, for example, air pressure decreases at altitudes above Earth's surface, thus providing a pressure-gradient force which counteracts the force of gravity on the atmosphere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
