"moisture, and air pollutants within the boundary layer. Cloud streets are usually more or less straight; rarely, cloud streets assume paisley patterns when the wind driving the clouds encounters an obstacle. Those cloud formations are known as von Kármán vortex streets. Horizontal rolls are counter-rotating vortex rolls that are nearly aligned with the mean wind of the Planetary Boundary Layer (PBL). They can be caused by convection in the presence of a moderate wind and/or dynamic inflection point instabilities in the mean wind profile. Early theory on the features predict that the vortices may be aligned up to 30° to"
"Vortex In fluid dynamics, a vortex (plural vortices/vortexes) is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved. Vortices form in stirred fluids, and may be observed in smoke rings, whirlpools in the wake of a boat, and the winds surrounding a tropical cyclone, tornado or dust devil. Vortices are a major component of turbulent flow. The distribution of velocity, vorticity (the curl of the flow velocity), as well as the concept of circulation are used to characterize vortices. In most vortices, the fluid flow velocity is greatest next"
"the popular media: hurricanes, tornadoes, waterspouts, aircraft trailing vortices (e.g., wingtip vortices), drainhole vortices (including the bathtub vortex), smoke rings, underwater bubble air rings, cavitation vortices behind ship propellers, and so on. In the technical literature a number of vortices that arise under special conditions also have names: the Kármán vortex street wake behind a bluff body, Taylor vortices between rotating cylinders, Görtler vortices in flow along a curved wall, etc. The theory of running water was greatly advanced by the researches of Gaspard Riche de Prony (1755–1839). From a collection of the best experiments by previous workers he selected"
"the formation of a bathtub vortex in outflowing water, and the build-up of a tornado by rising air currents. Helicity is vorticity in motion along a third axis in a corkscrew fashion. A rotating-vane vorticity meter was invented by Russian hydraulic engineer A. Ya. Milovich (1874–1958). In 1913 he proposed a cork with four blades attached as a device qualitatively showing the magnitude of the vertical projection of the vorticity and demonstrated a motion-picture photography of float's motion on the water surface in a model of river bend. Rotating-vane vorticity meters are commonly shown in educational films on continuum mechanics"
"Vortex ring A vortex ring, also called a toroidal vortex, is a torus-shaped vortex in a fluid or gas; that is, a region where the fluid mostly spins around an imaginary axis line that forms a closed loop. The dominant flow in a vortex ring is said to be toroidal, more precisely poloidal. Vortex rings are plentiful in turbulent flows of liquids and gases, but are rarely noticed unless the motion of the fluid is revealed by suspended particles—as in the smoke rings which are often produced intentionally or accidentally by smokers. Fiery vortex rings are also a commonly produced"
"hurricane-like storms four times larger than their terrestrial analogs. Each vortex has two ""eyes""—the centres of rotation, which are connected by distinct S-shaped cloud structures. Such double eyed structures are also called polar dipoles. Vortices rotate with the period of about 3 days in the direction of general super-rotation of the atmosphere. The linear wind speeds are 35–50 m/s near their outer edges and zero at the poles. The temperature at the cloud-tops in the each polar vortex is much higher than in the nearby polar collars reaching 250 K (−23 °C). The conventional interpretation of the polar vortices is"
"ring undergoes an oscillation in which it is first stretched in the vertical direction and squeezed in the horizontal direction, then passes through an intermediate state where it is circular, then is deformed in the opposite way (stretched in the horizontal direction and squeezed in the vertical) before reversing the process and returning to the original state. Vortex ring A vortex ring, also called a toroidal vortex, is a torus-shaped vortex in a fluid or gas; that is, a region where the fluid mostly spins around an imaginary axis line that forms a closed loop. The dominant flow in a"
"they can merge to make a vortex. Vortices also hold energy in its rotation of the fluid. If the energy is never removed, it would consist of circular motion forever. Vortex In fluid dynamics, a vortex (plural vortices/vortexes) is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved. Vortices form in stirred fluids, and may be observed in smoke rings, whirlpools in the wake of a boat, and the winds surrounding a tropical cyclone, tornado or dust devil. Vortices are a major component of turbulent flow. The distribution of"
"Wingtip vortices Wingtip vortices are circular patterns of rotating air left behind a wing as it generates lift. One wingtip vortex trails from the tip of each wing. Wingtip vortices are sometimes named ""trailing"" or ""lift-induced vortices"" because they also occur at points other than at the wing tips. Indeed, vorticity is trailed at any point on the wing where the lift varies span-wise (a fact described and quantified by the lifting-line theory); it eventually rolls up into large vortices near the wingtip, at the edge of flap devices, or at other abrupt changes in wing planform. Wingtip vortices are"
"fluid. In the dynamics of fluid, a vortex is fluid that revolves around the axis line. This fluid might be curved or straight. Vortices form from stirred liquids they might be observed in smoke rings, whirlpools, in the wake of a boat or the winds around a tornado or dust devil. Vortices are an important part of turbulent flow. Vortices can otherwise be known as a circular motion of a liquid. In the cases of the absence of forces, the liquid settles. This makes the water stay still instead of moving. When they are created, vortices can move, stretch, twist"
"Kolk (vortex) A kolk (colc) is an underwater vortex created when rapidly rushing water passes an underwater obstacle in boundary areas of high shear. High-velocity gradients produce a violently rotating column of water, similar to a tornado. Kolks can pluck multiple-ton blocks of rock and transport them in suspension for thousands of metres. Kolks leave clear evidence in the form of plucked-bedrock pits, called rock-cut basins or kolk lakes and downstream deposits of gravel-supported blocks that show percussion but no rounding. Kolks were first identified by the Dutch, who observed kolks hoisting several-ton blocks of riprap from dikes and transport"
"Multiple-vortex tornado A multiple-vortex tornado is a tornado that contains several vortices (called subvortices or suction vortices) rotating around, ""inside"" of, and as part of the main vortex. The only times multiple vortices may be visible are when the tornado is first forming or when condensation and debris is balanced enough so that subvortices are apparent without being obscured. They can add over 100 mph to the ground-relative wind in a tornado circulation, and are responsible for most (if not all) cases where narrow arcs of extreme destruction lie right next to weak damage within tornado paths. Suction vortices (or"
"curves but spirals or helices, respectively. This is the case in tornadoes and in drain whirlpools. A vortex with helical streamlines is said to be solenoidal. As long as the effects of viscosity and diffusion are negligible, the fluid in a moving vortex is carried along with it. In particular, the fluid in the core (and matter trapped by it) tends to remain in the core as the vortex moves about. This is a consequence of Helmholtz's second theorem. Thus vortices (unlike surface and pressure waves) can transport mass, energy and momentum over considerable distances compared to their size, with"
"look around this region of high shear for indications of individual vortex structures based on accepted definitions, like coherent vortices. Historically, a vortex has been thought of as a region in the flow where a group of vortex lines come together hence indicating the presence of a vortex core, with groups of instantaneous circular paths about the core. In 1991, Robinson defined a vortex structure to be a core consisting of convected low pressure regions, where instantaneous streamlines can form circles or spiral shapes relative to the plane normal to the vortex core plane. Although it is not possible to"
"purposes a ring vortex may be approximated as having a vortex-core of small cross-section. However a simple theoretical solution, called Hill's spherical vortex after the English mathematician Micaiah John Muller Hill (1856–1929), is known in which the vorticity is distributed within a sphere (the internal symmetry of the flow is however still annular). Such a structure or an electromagnetic equivalent has been suggested as an explanation for the internal structure of ball lightning. For example, Shafranov used a magnetohydrodynamic (MHD) analogy to Hill's stationary fluid mechanical vortex to consider the equilibrium conditions of axially symmetric MHD configurations, reducing the problem"
"cyclone is generally referred to as a hurricane (from the name of the ancient Central American deity of wind, Huracan), in the Indian and south Pacific oceans it is called a cyclone, and in the northwestern Pacific it is called a typhoon. The growth of instability in the vortices is not universal. For example, the size, intensity, moist-convection, surface evaporation, the value of potential temperature at each potential height can affect the nonlinear evolution of a vortex. Henry Piddington published 40 papers dealing with tropical storms from Calcutta between 1836 and 1855 in ""The Journal of the Asiatic Society"". He"
"Vortex ring toy A vortex ring toy is any of several toys that generate vortex rings – rolling torus-shapes of fluid, similar in structure to smoke rings – that move through the fluid (most often air, and sometimes water). Because of the way they rotate, a vortex ring can hold itself together and travel for quite a distance. Toys that blow air vortices, like the air vortex cannon, are mainly used to tickle people or animals at a distance with an ""invisible hand"". An interesting demonstration is to have a smoker blow a smoke cloud into the toy just before"
"firing, to create a large smoke ring. Some toys have a built-in smoke generator for this purpose. Vortex ring toy A vortex ring toy is any of several toys that generate vortex rings – rolling torus-shapes of fluid, similar in structure to smoke rings – that move through the fluid (most often air, and sometimes water). Because of the way they rotate, a vortex ring can hold itself together and travel for quite a distance. Toys that blow air vortices, like the air vortex cannon, are mainly used to tickle people or animals at a distance with an ""invisible hand""."
"Vortilon Vortilons are fixed aerodynamic devices on aircraft wings used to improve handling at low speeds. Vortilon is a contraction of VORTex and pYLON words (generating vortices as a leading-edge engine pylon does). Vortilons consist of one or more flat plates attached to the underside of the wing near its leading edge, aligned with the flight direction. When the speed is reduced and the aircraft approaches stall, the local flow at the leading edge is diverted outwards; this spanwise component of velocity around the vortilon creates a vortex streamed around the top surface, which energises the boundary layer. A more"
"Mesovortices Mesovortices are small scale rotational features found in convective storms, such as those found in bow echos, supercell thunderstorms, and the eyewall of tropical cyclones. They range in size from tens of miles in diameter to a mile or less, and can be immensely intense. ""Eyewall mesovortices"" are small scale rotational features found in the eyewalls of intense tropical cyclones. They are similar, in principle, to small ""suction vortices"" often observed in multiple-vortex tornadoes. In these vortices, wind speed can be up to 10% higher than in the rest of the eyewall. Eyewall mesovortices are most common during periods"
"important in forecasting supercells and the potential for tornadic activity. Vorticity In continuum mechanics, the vorticity is a pseudovector field that describes the ""local"" spinning motion of a continuum near some point (the tendency of something to rotate), as would be seen by an observer located at that point and traveling along with the flow. Conceptually, vorticity 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 vector would be twice the mean angular velocity vector of those particles"
"rings by shaking an incense stick. A vortex ring can also be created by a spinning propeller, as in a blender. Air vortices can form around the main rotor of a helicopter, causing a dangerous condition known as vortex ring state (VRS) or ""settling with power"". In this condition, air that moves down through the rotor turns outward, then up, inward, and then down through the rotor again. This re-circulation of flow can negate much of the lifting force and cause a catastrophic loss of altitude. Applying more power (increasing collective pitch) serves to further accelerate the downwash through which"
"Vortex lift Vortex lift is a form of lift generated by delta wings operating at high angles of attack. Vortex lift works by capturing vortices generated from the sharply swept leading edge of the wing. The vortex, formed roughly parallel to the leading edge of the wing, is trapped by the airflow and remains fixed to the upper surface of the wing. As the air flows around the leading edge, it flows over the trapped vortex and is pulled in and down to generate the lift. The major advantage of vortex lift is that it allows angles of attack that"
"Vorticella Vorticella is a genus of bell-shaped ciliates that have stalks to attach themselves to substrates. The stalks have contractile myonemes, allowing them to pull the cell body against substrates. The formation of the stalk happens after the free-swimming stage. The organism is aptly named “""Vorticella""” due to the beating cilia creating whirlpools, or vortices. It is also known as the “Bell Animalcule” due to its bell-shaped body. ""Vorticella"" was first described by Antonie van Leeuwenhoek in a letter dated October 9, 1676. Leeuwenhoek thought that ""Vorticella"" had two horns moving like horse ears near the oral part, which turned"
"Spinning tunnel Spinning tunnels—which are also known as vortex tunnels or rotating tunnels—are devices used at haunted attractions and amusement parks. When people walk through the center of a spinning tunnel they can experience vertigo and a loss of equilibrium as their brains receive conflicting signals from their bodies and senses. A prominent manufacturer of the attraction, GEP Productions, registered the trademark Vortex Tunnel, and has subsequently defended the trademark vigorously. The traditional version of the spinning tunnel consists of a tube made up of a series of rings which is typically up 10 feet high and up 20 feet"
"always oscillates.' "" Kármán vortex street In fluid dynamics, a Kármán vortex street (or a von Kármán vortex street) is a repeating pattern of swirling vortices, caused by a process known as vortex shedding, which is responsible for the unsteady separation of flow of a fluid around blunt bodies. It is named after the engineer and fluid dynamicist Theodore von Kármán, and is responsible for such phenomena as the ""singing"" of suspended telephone or power lines and the vibration of a car antenna at certain speeds. A vortex street will only form at a certain range of flow velocities, specified"
"coastal regions. Coastal roll clouds have been seen in many places, including California, the English Channel, Shetland Islands, the North Sea coast, coastal regions of Australia, and Nome, Alaska. Arcus cloud An arcus cloud is a low, horizontal cloud formation, usually appearing as an accessory cloud to a cumulonimbus. Roll clouds and shelf clouds are the two main types of arcus. Arcus clouds most frequently form along the leading edge or ""gust fronts"" of thunderstorm outflow; some of the most dramatic arcus formations mark the gust fronts of derecho-producing convective systems. Roll clouds also may arise in the absence of"
"Polar vortex A polar vortex is an upper level low-pressure area lying near the Earth's poles. There are two polar vortices in the Earth's atmosphere, overlying the North and South Poles. Each polar vortex is a persistent, large-scale, low pressure zone that rotates counter-clockwise at the North Pole (called a cyclone), and clockwise at the South Pole, i.e. both polar vortices rotate eastward around the poles. The bases of the two polar vortices are located in the middle and upper troposphere and extend into the stratosphere. Beneath that lies a large mass of cold, dense arctic air. The interface between"
"down the aircraft. Animals such as hummingbirds, and bats that eat pollen and nectar, are able to hover. They produce vortex lift with the sharp leading edges of their wings and change their wing shapes and curvatures to create stability in the lift. Vortex lift Vortex lift is a form of lift generated by delta wings operating at high angles of attack. Vortex lift works by capturing vortices generated from the sharply swept leading edge of the wing. The vortex, formed roughly parallel to the leading edge of the wing, is trapped by the airflow and remains fixed to the"
"birefringent vortices in materials. An optical singularity is a zero of an optical field. The phase in the field circulates around these points of zero intensity (giving rise to the name ""vortex""). Vortices are points in 2D fields and lines in 3D fields (as they have codimension two). Integrating the phase of the field around a path enclosing a vortex yields an integer multiple of 2. This integer is known as the topological charge, or strength, of the vortex. A hypergeometric-Gaussian mode (HyGG) has an optical vortex in its center. The beam, which has the form is a solution to"
"no identifiable clear inner core. Such vortices are more properly called steam whirls by analogy with the dust whirls of land. A precondition for the formation of steam devils is the presence of a layer of moist air on the water with the misty air (called arctic steam fog) being drawn upwards into fog streamers (non-rotating columns of steam fog). For this to happen the body of water must be unfrozen, and thus relatively warm, and there must be some wind of cold, dry air to form the fog. The cold air is warmed by the water and is humidified"
"vortices along the edge, with twisting masses of scud that may reach to the ground or be accompanied by rising dust. A very low shelf cloud accompanied by these signs is the best indicator that a potentially violent wind squall is approaching. An extreme example of this phenomenon looks almost like a tornado and is known as a gustnado. A roll cloud (""Cloud Atlas"" name "" volutus"") is a low, horizontal, tube-shaped, and relatively rare type of arcus cloud. They differ from shelf clouds by being completely detached from other cloud features. Roll clouds usually appear to be ""rolling"" about"
"contributions of all the forces formula_27 on all the individual horseshoe vortices, with formula_28 being the fluid density. formula_29 formula_30 formula_31 Here, formula_32 is the vortex's transverse segment vector, and formula_33 is the perturbation velocity at this segment's center location formula_34 (not at the collocation point). The lift and induced drag are obtained from the formula_35 components of the total force vector formula_25. For the case of zero sideslip these are given by formula_37 Vortex lattice method The Vortex lattice method, (VLM), is a numerical method used in computational fluid dynamics, mainly in the early stages of aircraft design and"