A

• Abbe prism
  Abbe prism
  In optics, an Abbe prism, named for its inventor, the German physicist Ernst Abbe, is a type of constant deviation dispersive prism similar to a Pellin–Broca prism.-Structure:...
  
  
• Absorption spectroscopy
  Absorption spectroscopy
  Absorption spectroscopy refers to spectroscopic techniques that measure the absorption of radiation, as a function of frequency or wavelength, due to its interaction with a sample. The sample absorbs energy, i.e., photons, from the radiating field. The intensity of the absorption varies as a...
  
  
• absorption spectrum
• Absorption wavemeter
  Absorption wavemeter
  The Absorption wavemeter is a simple device for the measurement of radio frequency energy at different frequencies.The device can be used by the users of radio equipment to check the approximate frequency of a strong signal source, and also to check the output of a transmitter for harmonics. Many...
  
  
• acoustics
  Acoustics
  Acoustics is the interdisciplinary science that deals with the study of all mechanical waves in gases, liquids, and solids including vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician while someone working in the field of acoustics...
  
  
• Acoustic wave
  Acoustic wave
  Acoustic waves are a type of longitudinal waves that propagate by means of adiabatic compression and decompression. Longitudinal waves are waves that have the same direction of vibration as their direction of travel. Important quantities for describing acoustic waves are sound pressure, particle...
  
  
• Acoustic wave equation
  Acoustic wave equation
  In physics, the acoustic wave equation governs the propagation of acoustic waves through a material medium. The form of the equation is a second order partial differential equation. The equation describes the evolution of acoustic pressure p or particle velocity u as a function of position r and...
  
  
• Acousto-optic effect
• Acousto-optic modulator
  Acousto-optic modulator
  An acousto-optic modulator , also called a Bragg cell, uses the acousto-optic effect to diffract and shift the frequency of light using sound waves . They are used in lasers for Q-switching, telecommunications for signal modulation, and in spectroscopy for frequency control. A piezoelectric...
  
  
• Acousto-optics
  Acousto-optics
  Acousto-optics is a branch of physics that studies the interactions between sound waves and light waves, especially the diffraction of laser light by ultrasound or sound in general.-Introduction:...
  
  
• Airy disc
  Airy disc
  In optics, the Airy disk and Airy pattern are descriptions of the best focused spot of light that a perfect lens with a circular aperture can make, limited by the diffraction of light....
  
  
• Airy wave theory
  Airy wave theory
  In fluid dynamics, Airy wave theory gives a linearised description of the propagation of gravity waves on the surface of a homogeneous fluid layer. The theory assumes that the fluid layer has a uniform mean depth, and that the fluid flow is inviscid, incompressible and irrotational...
  
  
• Alfvén wave
  Alfvén wave
  An Alfvén wave, named after Hannes Alfvén, is a type of magnetohydrodynamic wave.-Definition:An Alfvén wave in a plasma is a low-frequency travelling oscillation of the ions and the magnetic field...
  
  
• Alpha waves
  Alpha Waves
  Alpha Waves is an early 3D game that combines labyrinthine exploration with platform gameplay. By most definitions of the genre it could be considered to be the first 3D platform game, released in 1990, 6 years before the genre's seminal classic Super Mario 64...
  
  
• amphidromic point
  Amphidromic point
  An amphidromic point is a point within a tidal system where the tidal range is almost zero. The tidal range is zero at the amphidromic point and increases with distance from this point...
  
  
• amplitude
  Amplitude
  Amplitude is the magnitude of change in the oscillating variable with each oscillation within an oscillating system. For example, sound waves in air are oscillations in atmospheric pressure and their amplitudes are proportional to the change in pressure during one oscillation...
  
  
• amplitude modulation
  Amplitude modulation
  Amplitude modulation is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength of the transmitted signal in relation to the information being sent...
  
  
• analog sound vs. digital sound
  Analog sound vs. digital sound
  This article compares the two ways in which sound is recorded and stored. Actual sound waves consist of continuous variations in air pressure. Representations of these signals can be recorded using either digital or analog techniques....
  
  
• animal echolocation
  Animal echolocation
  Echolocation, also called biosonar, is the biological sonar used by several kinds of animals.Echolocating animals emit calls out to the environment and listen to the echoes of those calls that return from various objects near them. They use these echoes to locate and identify the objects...
  
  
• Antarctic Circumpolar Wave
  Antarctic Circumpolar Wave
  The Antarctic Circumpolar Wave is a coupled ocean/atmosphere wave that circles the Southern Ocean in approximately eight years. Since it is a wave-2 phenomenon at each fixed point in space a signal with a period of four years is seen...
  
  
• antiphase
• Apache Wave
• Aquamarine Power
  Aquamarine Power
  Aquamarine Power is a wave energy company, which was founded in 2005 to commercialise a wave energy device concept known as the Oyster wave energy converter. The company's head offices are based in Edinburgh...
  
  
• Arrayed waveguide grating
  Arrayed waveguide grating
  Arrayed waveguide gratings are commonly used as optical multiplexers in wavelength division multiplexed systems. These devices are capable of multiplexing a large number of wavelengths into a single optical fiber, thereby increasing the transmission capacity of optical networks considerably.The...
  
  
• artificial wave
  Artificial wave
  Artificial waves are man-made waves usually created on a specially designed surface or in a pool.Artificial waves are created in one or two ways. First, if the wave is created on a designed surface, water is shot over the surface at a high speed to create a wave...
  
  
• atmospheric diffraction
  Atmospheric diffraction
  Atmospheric diffraction is manifested in the following principal ways:* Fourier optics is the bending of light rays in the atmosphere, which results in remarkable visual displays of astronomical objects, such as depictions on this page....
  
  
• atmospheric wave
  Atmospheric wave
  An atmospheric wave is a periodic disturbance in the fields of atmospheric variables which may either propagate or not . Atmospheric waves range in spatial and temporal scale from large-scale planetary waves to minute sound waves...
  
  
• atmospheric waveguide
  Atmospheric waveguide
  An atmospheric waveguide is an atmospheric flow feature that improves the propagation of certain atmospheric waves.The effect arises because wave parameters such as group velocity or vertical wavenumber depend on mean flow direction and strength...
  
  
• Atomic clock
  Atomic clock
  An atomic clock is a clock that uses an electronic transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element...
  
  
• atomic mirror
• atom laser
  Atom laser
  An atom laser is a coherent state of propagating atoms. They are created out of a Bose–Einstein condensate of atoms that are output coupled using various techniques. Much like an optical laser, an atom laser is a coherent beam that behaves like a wave. There has been some argument that the term...
  
  
• audience wave
  Audience wave
  The wave or the Mexican wave is an example of metachronal rhythm achieved in a packed stadium when successive groups of spectators briefly stand and raise their arms...
  
  

B

• Babinet's principle
  Babinet's principle
  In physics, Babinet's principle is a theorem concerning diffraction that states that the diffraction pattern from an opaque body is identical to that from a hole of the same size and shape except for the overall forward beam intensity.-Explanation:...
  
  
• Backward wave oscillator
  Backward wave oscillator
  A backward wave oscillator , also called carcinotron or backward wave tube, is a vacuum tube that is used to generate microwaves up to the terahertz range. It belongs to the traveling-wave tube family...
  
  
• Bandwidth-limited pulse
  Bandwidth-limited pulse
  A bandwidth-limited pulse is a pulse of a wave that has the minimum possible duration for a given spectral bandwidth. Optical pulses of this type can be generated by mode-locked lasers...
  
  
• beat
  Beat (acoustics)
  In acoustics, a beat is an interference between two sounds of slightly different frequencies, perceived as periodic variations in volume whose rate is the difference between the two frequencies....
  
  
• Berry phase
• Bessel beam
  Bessel beam
  A Bessel beam is a field of electromagnetic, acoustic or even gravitational radiation whose amplitude is described by a Bessel function of the first kind. A true Bessel beam is non-diffractive. This means that as it propagates, it does not diffract and spread out; this is in contrast to the usual...
  
  
• beta wave
  Beta wave
  Beta wave, or beta rhythm, is the term used to designate the frequency range of human brain activity between 12 and 30 Hz . Beta waves are split into three sections: High Beta Waves ; Beta Waves ; and Low Beta Waves...
  
  
• black hole
  Black hole
  A black hole is a region of spacetime from which nothing, not even light, can escape. The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole. Around a black hole there is a mathematically defined surface called an event horizon that...
  
  
• blazar
  Blazar
  A blazar is a very compact quasar associated with a presumed supermassive black hole at the center of an active, giant elliptical galaxy...
  
  
• Bloch wave
  Bloch wave
  A Bloch wave or Bloch state, named after Felix Bloch, is the wavefunction of a particle placed in a periodic potential...
  
  
• Blueshift
• Boussinesq approximation (water waves)
  Boussinesq approximation (water waves)
  In fluid dynamics, the Boussinesq approximation for water waves is an approximation valid for weakly non-linear and fairly long waves. The approximation is named after Joseph Boussinesq, who first derived them in response to the observation by John Scott Russell of the wave of translation...
  
  
• bow wave
  Bow wave
  A bow wave is the wave that forms at the bow of a ship when it moves through the water. As the bow wave spreads out, it defines the outer limits of a ship's wake. A large bow wave slows the ship down, poses a risk to smaller boats, and in a harbor can cause damage to shore facilities and moored ships...
  
  
• Bragg diffraction
• Bragg's law
  Bragg's law
  In physics, Bragg's law gives the angles for coherent and incoherent scattering from a crystal lattice. When X-rays are incident on an atom, they make the electronic cloud move as does any electromagnetic wave...
  
  
• Breaking wave
  Breaking wave
  In fluid dynamics, a breaking wave is a wave whose amplitude reaches a critical level at which some process can suddenly start to occur that causes large amounts of wave energy to be transformed into turbulent kinetic energy...
  
  
• Bremsstrahlung
  Bremsstrahlung
  Bremsstrahlung is electromagnetic radiation produced by the deceleration of a charged particle when deflected by another charged particle, typically an electron by an atomic nucleus. The moving particle loses kinetic energy, which is converted into a photon because energy is conserved. The term is...
  
  , electromagnetic radiation
  Electromagnetic radiation
  Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...
  
  
• Brillouin scattering
  Brillouin scattering
  Brillouin scattering, named after Léon Brillouin, occurs when light in a medium interacts with time dependent optical density variations and changes its energy and path. The density variations may be due to acoustic modes, such as phonons, magnetic modes, such as magnons, or temperature gradients...
  
  
• Bullet bow shockwave
  Bullet bow shockwave
  A bullet bow shockwave is a physical and audible wave created in the air when a bullet travels at supersonic speeds; meaning faster than the speed of sound....
  
  
• Burgers' equation
  Burgers' equation
  Burgers' equation is a fundamental partial differential equation from fluid mechanics. It occurs in various areas of applied mathematics, such as modeling of gas dynamics and traffic flow...
  
  
• Business cycle
  Business cycle
  The term business cycle refers to economy-wide fluctuations in production or economic activity over several months or years...
  
  

C

• capillary wave
  Capillary wave
  A capillary wave is a wave traveling along the phase boundary of a fluid, whose dynamics are dominated by the effects of surface tension.Capillary waves are common in nature and the home, and are often referred to as ripples...
  
  
• carrier wave
  Carrier wave
  In telecommunications, a carrier wave or carrier is a waveform that is modulated with an input signal for the purpose of conveying information. This carrier wave is usually a much higher frequency than the input signal...
  
  
• Cherenkov radiation
  Cherenkov radiation
  Cherenkov radiation is electromagnetic radiation emitted when a charged particle passes through a dielectric medium at a speed greater than the phase velocity of light in that medium...
  
  
• Ernst Chladni
  Ernst Chladni
  Ernst Florens Friedrich Chladni was a German physicist and musician. His important works include research on vibrating plates and the calculation of the speed of sound for different gases. For this some call him the "Father of Acoustics"...
  
  
• chirp
  Chirp
  A chirp is a signal in which the frequency increases or decreases with time. In some sources, the term chirp is used interchangeably with sweep signal. It is commonly used in sonar and radar, but has other applications, such as in spread spectrum communications...
  
  
• circular polarization
  Circular polarization
  In electrodynamics, circular polarization of an electromagnetic wave is a polarization in which the electric field of the passing wave does not change strength but only changes direction in a rotary type manner....
  
  
• clapotis
  Clapotis
  In hydrodynamics, the clapotis is a non-breaking standing wave pattern, caused for example, by the reflection of a traveling surface wave train from a near vertical shoreline like a breakwater, seawall or steep cliff....
  
  
• closed waveguide
• cnoidal wave
  Cnoidal wave
  In fluid dynamics, a cnoidal wave is a nonlinear and exact periodic wave solution of the Korteweg–de Vries equation. These solutions are in terms of the Jacobi elliptic function cn, which is why they are coined cnoidal waves...
  
  
• coherence (physics)
  Coherence (physics)
  In physics, coherence is a property of waves that enables stationary interference. More generally, coherence describes all properties of the correlation between physical quantities of a wave....
  
  
• coherence length
  Coherence length
  In physics, coherence length is the propagation distance from a coherent source to a point where an electromagnetic wave maintains a specified degree of coherence. The significance is that interference will be strong within a coherence length of the source, but not beyond it...
  
  
• coherence time
  Coherence time
  For an electromagnetic wave, the coherence time is the time over which a propagating wave may be considered coherent...
  
  
• Cold wave
  Cold wave
  A cold wave is a weather phenomenon that is distinguished by a cooling of the air. Specifically, as used by the U.S. National Weather Service, a cold wave is a rapid fall in temperature within a 24 hour period requiring substantially increased protection to agriculture, industry, commerce, and...
  
  
• collimated light
  Collimated light
  Collimated light is light whose rays are parallel, and therefore will spread slowly as it propagates. The word is related to "collinear" and implies light that does not disperse with distance , or that will disperse minimally...
  
  
• Collimator
  Collimator
  A collimator is a device that narrows a beam of particles or waves. To "narrow" can mean either to cause the directions of motion to become more aligned in a specific direction or to cause the spatial cross section of the beam to become smaller.- Optical collimators :In optics, a collimator may...
  
  
• Compton effect
• computation of radiowave attenuation in the atmosphere
  Computation of radiowave attenuation in the atmosphere
  One of the causes of attenuation of radio propagation is the absorption by the atmosphere. There are many well known facts on the phenomenon and qualitative treatments in textbooks. A document published by the International Telecommunication Union...
  
  
• continuous phase modulation
  Continuous phase modulation
  Continuous phase modulation is a method for modulation of data commonly used in wireless modems. In contrast to other coherent digital phase modulation techniques where the carrier phase...
  
  
• continuous wave
  Continuous wave
  A continuous wave or continuous waveform is an electromagnetic wave of constant amplitude and frequency; and in mathematical analysis, of infinite duration. Continuous wave is also the name given to an early method of radio transmission, in which a carrier wave is switched on and off...
  
  
• Convective heat transfer
  Convective heat transfer
  Convective heat transfer, often referred to as convection, is the transfer of heat from one place to another by the movement of fluids. The presence of bulk motion of the fluid enhances the heat transfer between the solid surface and the fluid. Convection is usually the dominant form of heat...
  
  
• Coriolis frequency
  Coriolis frequency
  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 φ.f = 2 \Omega \sin \varphi.\,...
  
  
• coronal mass ejection
  Coronal mass ejection
  A coronal mass ejection is a massive burst of solar wind, other light isotope plasma, and magnetic fields rising above the solar corona or being released into space....
  
  
• Cosmic microwave background radiation
  Cosmic microwave background radiation
  In cosmology, cosmic microwave background radiation is thermal radiation filling the observable universe almost uniformly....
  
  
• Coulomb wave function
  Coulomb wave function
  In mathematics, a Coulomb wave function is a solution of the Coulomb wave equation, named after Charles-Augustin de Coulomb. They are used to describe the behavior of charged particles in a Coulomb potential and can be written in terms of confluent hypergeometric functions or Whittaker functions of...
  
  
• Cutoff frequency
  Cutoff frequency
  In physics and electrical engineering, a cutoff frequency, corner frequency, or break frequency is a boundary in a system's frequency response at which energy flowing through the system begins to be reduced rather than passing through.Typically in electronic systems such as filters and...
  
  
• cutoff wavelength
• cymatics
  Cymatics
  Cymatics is the study of visible sound and vibration, a subset of modal phenomena. Typically the surface of a plate, diaphragm, or membrane is vibrated, and regions of maximum and minimum displacement are made visible in a thin coating of particles, paste, or liquid...
  
  

D

• Damped wave
  Damped wave
  A damped wave is a wave whose amplitude of oscillation decreases with time, eventually going to zero. This term also refers to an early method of radio transmission produced by spark gap transmitters, which consisted of a series of damped electromagnetic waves...
  
  
• decollimation
• delta wave
  Delta wave
  A delta wave is a high amplitude brain wave with a frequency of oscillation between 0–4 hertz. Delta waves, like other brain waves, are recorded with an electroencephalogram and are usually associated with the deepest stages of sleep , also known as slow-wave sleep , and aid in characterizing the...
  
  
• dielectric waveguide
• diffraction
  Diffraction
  Diffraction refers to various phenomena which occur when a wave encounters an obstacle. Italian scientist Francesco Maria Grimaldi coined the word "diffraction" and was the first to record accurate observations of the phenomenon in 1665...
  
  
• direction finding
  Direction finding
  Direction finding refers to the establishment of the direction from which a received signal was transmitted. This can refer to radio or other forms of wireless communication...
  
  
• dispersion (optics)
  Dispersion (optics)
  In optics, dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency, or alternatively when the group velocity depends on the frequency.Media having such a property are termed dispersive media...
  
  
• dispersion (water waves)
  Dispersion (water waves)
  In fluid dynamics, dispersion of water waves generally refers to frequency dispersion, which means that waves of different wavelengths travel at different phase speeds. Water waves, in this context, are waves propagating on the water surface, and forced by gravity and surface tension...
  
  
• dispersion relation
  Dispersion relation
  In physics and electrical engineering, dispersion most often refers to frequency-dependent effects in wave propagation. Note, however, that there are several other uses of the word "dispersion" in the physical sciences....
  
  
• dominant wavelength
  Dominant wavelength
  In color science, the dominant wavelength and complementary wavelength are ways of describing non-spectral light mixtures in terms of the spectral light that evokes an identical perception of hue....
  
  
• Doppler effect
  Doppler effect
  The Doppler effect , named after Austrian physicist Christian Doppler who proposed it in 1842 in Prague, is the change in frequency of a wave for an observer moving relative to the source of the wave. It is commonly heard when a vehicle sounding a siren or horn approaches, passes, and recedes from...
  
  
• Doppler radar
  Doppler radar
  A Doppler radar is a specialized radar that makes use of the Doppler effect to produce velocity data about objects at a distance. It does this by beaming a microwave signal towards a desired target and listening for its reflection, then analyzing how the frequency of the returned signal has been...
  
  
• Draupner wave
  Draupner wave
  The Draupner wave or New Year's wave was the first rogue wave to be detected by a measuring instrument, occurring at the Draupner platform in the North Sea off the coast of Norway on January 1, 1995...
  
  
• Duhamel's principle
  Duhamel's principle
  In mathematics, and more specifically in partial differential equations, Duhamel's principle is a general method for obtaining solutions to inhomogeneous linear evolution equations like the heat equation, wave equation, and vibrating plate equation...
  
  
• Douglas Sea Scale
  Douglas Sea Scale
  The Douglas Sea Scale is a scale which measures the height of the waves and also measures the swell of the sea. The scale is very simple to follow. The Douglas Sea Scale is expressed in one of 10 degrees.- The Scale :...
  
  

E

• e-skip
• Earthquake
  Earthquake
  An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
  
  
• echo (phenomenon)
  Echo (phenomenon)
  In audio signal processing and acoustics, an echo is a reflection of sound, arriving at the listener some time after the direct sound. Typical examples are the echo produced by the bottom of a well, by a building, or by the walls of an enclosed room and an empty room. A true echo is a single...
  
  
• echolocation (animal)
• echolocation (human)
• echo sounding
  Echo sounding
  Echo sounding is the technique of using sound pulses directed from the surface or from a submarine vertically down to measure the distance to the bottom by means of sound waves. This information is then typically used for navigation purposes or in order to obtain depths for charting purposes...
  
  
• Eddy (fluid dynamics)
  Eddy (fluid dynamics)
  In fluid dynamics, an eddy is the swirling of a fluid and the reverse current created when the fluid flows past an obstacle. The moving fluid creates a space devoid of downstream-flowing fluid on the downstream side of the object...
  
  
• edge wave
  Edge wave
  In fluid dynamics, an edge wave is a surface gravity wave fixed by refraction against a rigid boundary, often a shoaling beach. Progressive edge waves travel along this boundary, varying sinusoidally along it and diminishing exponentially in the offshore direction....
  
  
• eikonal equation
  Eikonal equation
  The eikonal equation is a non-linear partial differential equation encountered in problems of wave propagation, when the wave equation is approximated using the WKB theory...
  
  
• Ekman layer
• Ekman spiral
  Ekman spiral
  The Ekman spiral refers to a structure of currents or winds near a horizontal boundary in which the flow direction rotates as one moves away from the boundary. It derives its name from the Swedish oceanographer Vagn Walfrid Ekman...
  
  
• Ekman transport
  Ekman transport
  Ekman transport, part of Ekman motion theory first investigated in 1902 by Vagn Walfrid Ekman , is the term given for the 90 degree net transport of the surface layer due to wind forcings...
  
  
• Electromagnetic electron wave
  Electromagnetic electron wave
  An electromagnetic electron wave is a wave in a plasma which has a magnetic field component and in which primarily the electrons oscillate.In an unmagnetized plasma, an electromagnetic electron wave is simply a light wave modified by the plasma...
  
  
• electromagnetic radiation
  Electromagnetic radiation
  Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...
  
  
• electromagnetic wave
• electromagnetic wave cut-off
• electron
  Electron
  The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
  
  
• Elliott wave
• elliptical polarization
  Elliptical polarization
  In electrodynamics, elliptical polarization is the polarization of electromagnetic radiation such that the tip of the electric field vector describes an ellipse in any fixed plane intersecting, and normal to, the direction of propagation...
  
  
• El Niño-Southern Oscillation
  El Niño-Southern Oscillation
  El Niño/La Niña-Southern Oscillation, or ENSO, is a quasiperiodic climate pattern that occurs across the tropical Pacific Ocean roughly every five years...
  
  
• Electroencephalography
  Electroencephalography
  Electroencephalography is the recording of electrical activity along the scalp. EEG measures voltage fluctuations resulting from ionic current flows within the neurons of the brain...
  
  
• emission spectrum
  Emission spectrum
  The emission spectrum of a chemical element or chemical compound is the spectrum of frequencies of electromagnetic radiation emitted by the element's atoms or the compound's molecules when they are returned to a lower energy state....
  
  
• Equatorial Rossby wave
• Equatorial waves
  Equatorial waves
  Equatorial waves are waves trapped close to the equator, meaning that they decay rapidly away from the equator, but can propagate in the longitudinal and vertical directions. Wave trapping is the result of the Earth's rotation and its spherical shape which combine to cause the magnitude of the...
  
  
• essential bandwidth
  Essential bandwidth
  In signal processing, the essential bandwidth is the portion of a signal spectrum in the frequency domain which contains most of the energy of the signal....
  
  
• evanescent wave
  Evanescent wave
  An evanescent wave is a nearfield standing wave with an intensity that exhibits exponential decay with distance from the boundary at which the wave was formed. Evanescent waves are a general property of wave-equations, and can in principle occur in any context to which a wave-equation applies...
  
  
• Extratropical cyclone
  Extratropical cyclone
  Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
  
  
• extremely low frequency
  Extremely low frequency
  Extremely low frequency is a term used to describe radiation frequencies from 3 to 300 Hz. In atmosphere science, an alternative definition is usually given, from 3 Hz to 3 kHz...
  
  

F

• Fabry–Pérot interferometer
• F wave
  F wave
  In neuroscience, an F wave is the second of two voltage changes observed after electrical stimulation is applied to the skin surface above the distal region of a nerve...
  
  
• Faraday wave
  Faraday wave
  Faraday waves, also known as Faraday ripples, named after Michael Faraday, are nonlinear standing waves that appear on liquids enclosed by a vibrating receptacle. When the vibration frequency exceeds a critical value, the flat hydrostatic surface becomes unstable. This is known as the Faraday...
  
  
• Fetch (geography)
  Fetch (geography)
  The fetch, often called the fetch length, is the length of water over which a given wind has blown. It is used in geography and meteorology and is usually associated with coastal erosion. It plays a large part in longshore drift as well....
  
  
• Fourier series
  Fourier series
  In mathematics, a Fourier series decomposes periodic functions or periodic signals into the sum of a set of simple oscillating functions, namely sines and cosines...
  
  
• Fraunhofer diffraction
  Fraunhofer diffraction
  In optics, the Fraunhofer diffraction equation is used to model the diffraction of waves when the diffraction pattern is viewed at a long distance from the diffracting object, and also when it is viewed at the focal plane of an imaging lens....
  
  
• Fraunhofer distance
• freak wave
  Freak wave
  Rogue waves are relatively large and spontaneous ocean surface waves that occur far out in sea, and are a threat even to large ships and ocean liners...
  
  
• frequency
  Frequency
  Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...
  
  
• frequency modulation
  Frequency modulation
  In telecommunications and signal processing, frequency modulation conveys information over a carrier wave by varying its instantaneous frequency. This contrasts with amplitude modulation, in which the amplitude of the carrier is varied while its frequency remains constant...
  
  
• Fresnel–Arago laws
• Fresnel diffraction
  Fresnel diffraction
  In optics, the Fresnel diffraction equation for near-field diffraction, is an approximation of Kirchhoff-Fresnel diffraction that can be applied to the propagation of waves in the near field....
  
  
• Fresnel equations
  Fresnel equations
  The Fresnel equations , deduced by Augustin-Jean Fresnel , describe the behaviour of light when moving between media of differing refractive indices...
  
  
• Fresnel integral
  Fresnel integral
  250px|thumb|S and C The maximum of C is about 0.977451424. If πt²/2 were used instead of t², then the image would be scaled vertically and horizontally ....
  
  
• Fresnel lens
  Fresnel lens
  A Fresnel lens is a type of lens originally developed by French physicist Augustin-Jean Fresnel for lighthouses.The design allows the construction of lenses of large aperture and short focal length without the mass and volume of material that would be required by a lens of conventional design...
  
  
• Fresnel number
  Fresnel number
  The Fresnel number F, named after the physicist Augustin-Jean Fresnel, is a dimensionless number occurring in optics, in particular in diffraction theory....
  
  
• Fresnel rhomb
  Fresnel rhomb
  A Fresnel rhomb is a prism-like device designed in 1817 by Augustin-Jean Fresnel for changing the polarization of light waves to be circularly polarized. Though the result is similar to that of using a wave plate, the rhomb does not depend on birefringent properties of the material...
  
  
• Fresnel zone
  Fresnel zone
  In optics and radio communications , a Fresnel zone , named for physicist Augustin-Jean Fresnel, is one of a number of concentric ellipsoids which define volumes in the radiation pattern of a circular aperture...
  
  
• fundamental frequency
  Fundamental frequency
  The fundamental frequency, often referred to simply as the fundamental and abbreviated f0, is defined as the lowest frequency of a periodic waveform. In terms of a superposition of sinusoids The fundamental frequency, often referred to simply as the fundamental and abbreviated f0, is defined as the...
  
  
• F wave
  F wave
  In neuroscience, an F wave is the second of two voltage changes observed after electrical stimulation is applied to the skin surface above the distal region of a nerve...
  
  

G

• gamma ray
  Gamma ray
  Gamma radiation, also known as gamma rays or hyphenated as gamma-rays and denoted as γ, is electromagnetic radiation of high frequency . Gamma rays are usually naturally produced on Earth by decay of high energy states in atomic nuclei...
  
  
• gamma ray burst
  Gamma ray burst
  Gamma-ray bursts are flashes of gamma rays associated with extremely energetic explosions that have been observed in distant galaxies. They are the most luminous electromagnetic events known to occur in the universe. Bursts can last from ten milliseconds to several minutes, although a typical...
  
  
• Gamma wave
  Gamma wave
  A gamma wave is a pattern of neural oscillation in humans with a frequency between 25 to 100 Hz, though 40 Hz is prototypical.According to a popular theory, gamma waves may be implicated in creating the unity of conscious perception...
  
  
• Gaussian beam
  Gaussian beam
  In optics, a Gaussian beam is a beam of electromagnetic radiation whose transverse electric field and intensity distributions are well approximated by Gaussian functions. Many lasers emit beams that approximate a Gaussian profile, in which case the laser is said to be operating on the fundamental...
  
  
• geometric optics, geometrical optics
  Geometrical optics
  Geometrical optics, or ray optics, describes light propagation in terms of "rays". The "ray" in geometric optics is an abstraction, or "instrument", which can be used to approximately model how light will propagate. Light rays are defined to propagate in a rectilinear path as far as they travel in...
  
  
• Geostrophic current
• gravitational radiation
• gravity wave
  Gravity wave
  In fluid dynamics, gravity waves are waves generated in a fluid medium or at the interface between two media which has the restoring force of gravity or buoyancy....
  
  
• groundwave
• group delay
  Group delay
  Group delay is a measure of the time delay of the amplitude envelopes of the various sinusoidal components of a signal through a device under test, and is a function of frequency for each component...
  
  
• group velocity
  Group velocity
  The group velocity of a wave is the velocity with which the overall shape of the wave's amplitudes — known as the modulation or envelope of the wave — propagates through space....
  
  

H

• harmonic
  Harmonic
  A harmonic of a wave is a component frequency of the signal that is an integer multiple of the fundamental frequency, i.e. if the fundamental frequency is f, the harmonics have frequencies 2f, 3f, 4f, . . . etc. The harmonics have the property that they are all periodic at the fundamental...
  
  
• holography
  Holography
  Holography is a technique that allows the light scattered from an object to be recorded and later reconstructed so that when an imaging system is placed in the reconstructed beam, an image of the object will be seen even when the object is no longer present...
  
  
• heat wave
  Heat wave
  A heat wave is a prolonged period of excessively hot weather, which may be accompanied by high humidity. There is no universal definition of a heat wave; the term is relative to the usual weather in the area...
  
  
• human echolocation
  Human echolocation
  Human echolocation is the ability of humans to detect objects in their environment by sensing echoes from those objects. By actively creating sounds – for example, by tapping their canes, lightly stomping their foot or making clicking noises with their mouths – people trained to orientate with...
  
  
• hundred-year wave
  Hundred-year wave
  A hundred-year wave is a statistically projected water wave, the height of which, on average, is met or exceeded once in a hundred years for a given location. The likelihood of this wave height being attained at least once in the hundred-year period is 63%...
  
  
• hurricane
• Huygens' principle
• hydraulic jump
  Hydraulic jump
  A hydraulic jump is a phenomenon in the science of hydraulics which is frequently observed in open channel flow such as rivers and spillways. When liquid at high velocity discharges into a zone of lower velocity, a rather abrupt rise occurs in the liquid surface...
  
  
• Hydrography
  Hydrography
  Hydrography is the measurement of the depths, the tides and currents of a body of water and establishment of the sea, river or lake bed topography and morphology. Normally and historically for the purpose of charting a body of water for the safe navigation of shipping...
  
  
• Hydropower
  Hydropower
  Hydropower, hydraulic power, hydrokinetic power or water power is power that is derived from the force or energy of falling water, which may be harnessed for useful purposes. Since ancient times, hydropower has been used for irrigation and the operation of various mechanical devices, such as...
  
  
• Hyperbolic partial differential equation
  Hyperbolic partial differential equation
  In mathematics, a hyperbolic partial differential equation of order n is a partial differential equation that, roughly speaking, has a well-posed initial value problem for the first n−1 derivatives. More precisely, the Cauchy problem can be locally solved for arbitrary initial data along...
  
  

I

• in phase
• infragravity wave
  Infragravity wave
  Infragravity waves are surface gravity waves with frequencies lower than the wind waves – consisting of both wind sea and swell – so corresponding with the part of the wave spectrum lower than the frequencies directly generated by forcing through the wind....
  
  
• Inhomogeneous electromagnetic wave equation
  Inhomogeneous electromagnetic wave equation
  Localized time-varying charge and current densities can act as sources of electromagnetic waves in a vacuum. Maxwell's equations can be written in the form of a inhomogeneous electromagnetic wave equation with sources...
  
  
• Interference (wave propagation)
• inertial wave
  Inertial wave
  Inertial waves, also known as inertial oscillations, are a type of mechanical wave possible in rotating fluids. Unlike surface gravity waves commonly seen at the beach or in the bathtub, inertial waves travel through the interior of the fluid, not at the surface...
  
  
• Infrared gas analyzer
  Infrared gas analyzer
  ]An infrared gas analyzer measures trace gases by determining the absorption of an emitted infrared light source through a certain air sample. Trace gases found in the Earth's atmosphere get excited under specific wavelengths found in the infrared range. The concept behind the technology can be...
  
  
• interferometry
  Interferometry
  Interferometry refers to a family of techniques in which electromagnetic waves are superimposed in order to extract information about the waves. An instrument used to interfere waves is called an interferometer. Interferometry is an important investigative technique in the fields of astronomy,...
  
  
• internal wave
  Internal wave
  Internal waves are gravity waves that oscillate within, rather than on the surface of, a fluid medium. They are one of many types of wave motion in stratified fluids . A simple example is a wave propagating on the interface between two fluids of different densities, such as oil and water...
  
  
• inverse scattering transform
  Inverse scattering transform
  In mathematics, the inverse scattering transform is a method for solving some non-linear partial differential equations. It is one of the most important developments in mathematical physics in the past 40 years...
  
  
• Ion acoustic wave
  Ion acoustic wave
  An ion acoustic wave is one type of longitudinal oscillation of the ions and electrons in a plasma, much like acoustic waves traveling in neutral gas. However, because the waves propagate through positively charged ions, ion acoustic waves can interact with their electromagnetic fields, as well as...
  
  
• Irradiance
  Irradiance
  Irradiance is the power of electromagnetic radiation per unit area incident on a surface. Radiant emittance or radiant exitance is the power per unit area radiated by a surface. The SI units for all of these quantities are watts per square meter , while the cgs units are ergs per square centimeter...
  
  

L

• Lamb waves
  Lamb waves
  Lamb waves propagate in solid plates. They are elastic waves whose particle motion lies in the plane that contains the direction of wave propagation and the plate normal . In 1917, the English mathematician Horace Lamb published his classic analysis and description of acoustic waves of this type....
  
  
• Landau damping
  Landau damping
  In physics, Landau damping, named after its discoverer, the eminent Soviet physicist Lev Davidovich Landau, is the effect of damping of longitudinal space charge waves in plasma or a similar environment. This phenomenon prevents an instability from developing, and creates a region of stability in...
  
  
• Lee wave
• linear elasticity
  Linear elasticity
  Linear elasticity is the mathematical study of how solid objects deform and become internally stressed due to prescribed loading conditions. Linear elasticity models materials as continua. Linear elasticity is a simplification of the more general nonlinear theory of elasticity and is a branch of...
  
  
• linear polarization
  Linear polarization
  In electrodynamics, linear polarization or plane polarization of electromagnetic radiation is a confinement of the electric field vector or magnetic field vector to a given plane along the direction of propagation...
  
  
• list of waves named after people
• longitudinal mode
  Longitudinal mode
  For the longitudinal mode of conduction of electric currents, see Common modeA longitudinal mode of a resonant cavity is a particular standing wave pattern formed by waves confined in the cavity. The longitudinal modes correspond to the wavelengths of the wave which are reinforced by constructive...
  
  
• longitudinal wave
  Longitudinal wave
  Longitudinal waves, as known as "l-waves", are waves that have the same direction of vibration as their direction of travel, which means that the movement of the medium is in the same direction as or the opposite direction to the motion of the wave. Mechanical longitudinal waves have been also...
  
  
• longwave
  Longwave
  In radio, longwave refers to parts of radio spectrum with relatively long wavelengths. The term is a historic one dating from the early 20th century, when the radio spectrum was considered to consist of long, medium and short wavelengths...
  
  
• ong wavelength limit
• Love wave
  Love wave
  In elastodynamics, Love waves are horizontally polarized shear waves guided by an elastic layer, which is "welded" to an elastic half space on one side while bordering a vacuum on the other side...
  
  

M

• Mach wave
  Mach wave
  In fluid dynamics, a Mach wave is a pressure wave traveling with the speed of sound caused by a slight change of pressure added to a compressible flow. These weak waves can combine in supersonic flow to become a shock wave if sufficient Mach waves are present at any location. Such a shock wave is...
  
  
• Mach–Zehnder interferometer
• Maelstrom
  Maelstrom
  A maelstrom is a very powerful whirlpool; a large, swirling body of water. A free vortex, it has considerable downdraft. The power of tidal whirlpools tends to be exaggerated by laymen. There are virtually no stories of large ships ever being sucked into a maelstrom, although smaller craft are in...
  
  
• Magnetometer
  Magnetometer
  A magnetometer is a measuring instrument used to measure the strength or direction of a magnetic field either produced in the laboratory or existing in nature...
  
  
• Magnetosonic wave
  Magnetosonic wave
  A magnetosonic wave is a longitudinal wave of ions in a magnetized plasma propagating perpendicular to the stationary magnetic field...
  
  
• matter wave
• Maxwell's equations
  Maxwell's equations
  Maxwell's equations are a set of partial differential equations that, together with the Lorentz force law, form the foundation of classical electrodynamics, classical optics, and electric circuits. These fields in turn underlie modern electrical and communications technologies.Maxwell's equations...
  
  
• Mayer waves
  Mayer waves
  Mayer waves are waves in arterial blood pressure brought about by oscillations in baroreceptor and chemoreceptor reflex control systems. The waves are seen both in the ECG and in blood pressure curves and have a frequency about 0.1 Hz...
  
  
• Mechanical wave
  Mechanical wave
  A mechanical or material wave is a wave that needs a medium to travel. The oscillating material does not move far from its initial equilibrium position, as only the energy is transferred by connected particles. Ocean waves and sound are examples of this phenomenon.A mechanical wave requires an...
  
  
• Medical ultrasonography
  Medical ultrasonography
  Diagnostic sonography is an ultrasound-based diagnostic imaging technique used for visualizing subcutaneous body structures including tendons, muscles, joints, vessels and internal organs for possible pathology or lesions...
  
  
• mediumwave
  Mediumwave
  Medium wave is the part of the medium frequency radio band used mainly for AM radio broadcasting. For Europe the MW band ranges from 526.5 kHz to 1606.5 kHz...
  
  
• megatsunami
  Megatsunami
  Megatsunami is an informal term to describe a tsunami that has initial wave heights that are much larger than normal tsunamis...
  
  
• microbarom
  Microbarom
  In acoustics, microbaroms, also known as the "voice of the sea",are a class of atmospheric infrasonic waves generated in marine stormsby a non-linear interaction of ocean surface waves with the atmosphere....
  
  
• microwave
  Microwave
  Microwaves, a subset of radio waves, have wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz and 300 GHz. This broad definition includes both UHF and EHF , and various sources use different boundaries...
  
  
• microwave auditory effect
  Microwave auditory effect
  The microwave auditory effect, also known as the microwave hearing effect or the Frey effect, consists of audible clicks induced by pulsed/modulated microwave frequencies. The clicks are generated directly inside the human head without the need of any receiving electronic device...
  
  
• microwave oven
  Microwave oven
  A microwave oven is a kitchen appliance that heats food by dielectric heating, using microwave radiation to heat polarized molecules within the food...
  
  
• microwave plasma
  Microwave plasma
  Microwave plasma is a type of plasma, that has high frequency electromagnetic radiation in the GHz range. It is capable of exciting electrodeless gas discharges.-Properties of microwave-excited plasma:...
  
  
• microwaving
• Mie scattering
• millimeter cloud radar
  Millimeter cloud radar
  Millimeter-wave cloud radar is a radar system designed to monitor cloud structure with wavelengths about ten times shorter than those used in conventional storm surveillance radars such as NEXRAD....
  
  
• modulation
  Modulation
  In electronics and telecommunications, modulation is the process of varying one or more properties of a high-frequency periodic waveform, called the carrier signal, with a modulating signal which typically contains information to be transmitted...
  
  
• Monochromatic electromagnetic plane wave
  Monochromatic electromagnetic plane wave
  In general relativity, the monochromatic electromagnetic plane wave spacetime is the analog of the monochromatic plane waves known from Maxwell's theory...
  
  
• monochromator
  Monochromator
  A monochromator is an optical device that transmits a mechanically selectable narrow band of wavelengths of light or other radiation chosen from a wider range of wavelengths available at the input...
  
  
• Moonlight
  Moonlight
  Moonlight is the light that reaches Earth from the Moon. This light does not originate from the Moon, but from sunlight. The Moon does not, however, reflect sunlight like a mirror, but it reflects light from those portions of its surface which the Sun's light strikes. See diffuse reflection.In...
  
  
• Morning Glory cloud
  Morning glory cloud
  The Morning Glory cloud is a rare meteorological phenomenon occasionally observed in different locations around the world. The southern part of Northern Australia's Gulf of Carpentaria is the only known location where it can be predicted and observed on a more or less regular basis. The settlement...
  
  
• multipath propagation
• mu wave
  Mu wave
  Mu waves, also known as the comb or wicket rhythm, are electromagnetic oscillations in the frequency range of 8–13 Hz and appear in bursts of at 9 – 11 Hz. Mu wave patterns arise from synchronous and coherent electrical activity of large groups of neurons in the human brain...
  
  

N

• Neural oscillation
• Nondispersive infrared sensor
• nonlinear Schrödinger equation
  Nonlinear Schrödinger equation
  In theoretical physics, the nonlinear Schrödinger equation is a nonlinear version of Schrödinger's equation. It is a classical field equation with applications to optics and water waves. Unlike the Schrödinger equation, it never describes the time evolution of a quantum state...
  
  
• nonlinear wave
• nonlinear X-wave
• normal mode
  Normal mode
  A normal mode of an oscillating system is a pattern of motion in which all parts of the system move sinusoidally with the same frequency and with a fixed phase relation. The frequencies of the normal modes of a system are known as its natural frequencies or resonant frequencies...
  
  
• neutron
  Neutron
  The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of...
  
  

O

• ocean surface wave
  Ocean surface wave
  In fluid dynamics, wind waves or, more precisely, wind-generated waves are surface waves that occur on the free surface of oceans, seas, lakes, rivers, and canals or even on small puddles and ponds. They usually result from the wind blowing over a vast enough stretch of fluid surface. Waves in the...
  
  
• oscillon
  Oscillon
  In physics, an oscillon is a soliton-like phenomenon that occurs in granular and other dissipative media. Oscillons in granular media result from vertically vibrating a plate with a layer of uniform particles placed freely on top...
  
  
• Optical fiber
  Optical fiber
  An optical fiber is a flexible, transparent fiber made of a pure glass not much wider than a human hair. It functions as a waveguide, or "light pipe", to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of...
  
  
• optical waveguide
• Outgoing longwave radiation
  Outgoing longwave radiation
  Outgoing Longwave Radiation is the energy leaving the earth as infrared radiation at low energy. OLR is a critical component of the Earth’s radiation budget and represents the total radiation going to space emitted by the atmosphere...
  
  
• out of phase
• overtone
  Overtone
  An overtone is any frequency higher than the fundamental frequency of a sound. The fundamental and the overtones together are called partials. Harmonics are partials whose frequencies are whole number multiples of the fundamental These overlapping terms are variously used when discussing the...
  
  
• Oyster wave energy converter
  Oyster wave energy converter
  The Oyster is a hydro-electric wave energy device that uses the motion of ocean waves to generate electricity. It is made up of a Power Connector Frame , which is bolted to the seabed, and a Power Capture Unit . The PCU is a hinged buoyant flap that moves back and forth with movement of the waves...
  
  

P

• P-wave
  P-wave
  P-waves are a type of elastic wave, also called seismic waves, that can travel through gases , solids and liquids, including the Earth. P-waves are produced by earthquakes and recorded by seismographs...
  
  
• parabolic reflector
  Parabolic reflector
  A parabolic reflector is a reflective device used to collect or project energy such as light, sound, or radio waves. Its shape is that of a circular paraboloid, that is, the surface generated by a parabola revolving around its axis...
  
  
• Periodic function
  Periodic function
  In mathematics, a periodic function is a function that repeats its values in regular intervals or periods. The most important examples are the trigonometric functions, which repeat over intervals of length 2π radians. Periodic functions are used throughout science to describe oscillations,...
  
  
• phase (waves)
  Phase (waves)
  Phase in waves is the fraction of a wave cycle which has elapsed relative to an arbitrary point.-Formula:The phase of an oscillation or wave refers to a sinusoidal function such as the following:...
  
  
• phase difference
• phase inversion
  Phase inversion
  Phase inversion means the swapping of the two poles of an alternating current source. A phase inversion is neither a time shift nor a phase shift, but simply a swap of plus and minus....
  
  
• phase modulation
  Phase modulation
  Phase modulation is a form of modulation that represents information as variations in the instantaneous phase of a carrier wave.Unlike its more popular counterpart, frequency modulation , PM is not very widely used for radio transmissions...
  
  
• phase velocity
  Phase velocity
  The phase velocity of a wave is the rate at which the phase of the wave propagates in space. This is the speed at which the phase of any one frequency component of the wave travels. For such a component, any given phase of the wave will appear to travel at the phase velocity...
  
  
• phonon
  Phonon
  In physics, a phonon is a collective excitation in a periodic, elastic arrangement of atoms or molecules in condensed matter, such as solids and some liquids...
  
  
• photon
  Photon
  In physics, a photon is an elementary particle, the quantum of the electromagnetic interaction and the basic unit of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force...
  
  
• pitch shifter (audio processor)
• Planck constant
  Planck constant
  The Planck constant , also called Planck's constant, is a physical constant reflecting the sizes of energy quanta in quantum mechanics. It is named after Max Planck, one of the founders of quantum theory, who discovered it in 1899...
  
  
• Planck's law
• plane wave
  Plane wave
  In the physics of wave propagation, a plane wave is a constant-frequency wave whose wavefronts are infinite parallel planes of constant peak-to-peak amplitude normal to the phase velocity vector....
  
  
• polarization (waves)
• Ponto-geniculo-occipital waves, PGO waves
  PGO waves
  Ponto-geniculo-occipital waves or PGO waves are phasic field potentials. These waves can be recorded from the pons, the lateral geniculate nucleus , and the occipital cortex regions of the brain, where these waveforms originate...
  
  
• power standing wave ratio
• pp-wave spacetime
  Pp-wave spacetime
  In general relativity, the pp-wave spacetimes, or pp-waves for short, are an important family of exact solutions of Einstein's field equation. These solutions model radiation moving at the speed of light...
  
  
• pressure wave
• Prism
  Prism
  -Science and mathematics:* Prism , a transparent object which refracts light** Dispersive prism, the most familiar type of optical prism* Prism , a kind of polyhedron* Prism , a type of sedimentary deposit-Books, comics and magazines:...
  
  
• proton
  Proton
  The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number....
  
  
• pulsar
  Pulsar
  A pulsar is a highly magnetized, rotating neutron star that emits a beam of electromagnetic radiation. The radiation can only be observed when the beam of emission is pointing towards the Earth. This is called the lighthouse effect and gives rise to the pulsed nature that gives pulsars their name...
  
  
• Pulsar wind nebula
  Pulsar wind nebula
  A pulsar wind nebula is a nebula powered by the pulsar wind of a pulsar. At the early stages of their evolution, pulsar wind nebulae are often found inside the shells of supernova remnants...
  
  
• pulse-density modulation
  Pulse-density modulation
  Pulse-density modulation, or PDM, is a form of modulation used to represent an analog signal with digital data. In a PDM signal, specific amplitude values are not encoded into pulses of different size as they would be in PCM. Instead, it is the relative density of the pulses that corresponds to...
  
  
• Pulse wave velocity
  Pulse wave velocity
  Pulse wave velocity is a measure of arterial stiffness. It is easy to measure invasively and non-invasively in humans, is highly reproducible, has a strong correlation between PWV and cardiovascular events and all-cause mortality, and was recognized by the European Society of Hypertension as...
  
  

Q

• QT interval
  QT interval
  In cardiology, the QT interval is a measure of the time between the start of the Q wave and the end of the T wave in the heart's electrical cycle. In general, the QT interval represents electrical depolarization and repolarization of the left and right ventricles...
  
  
• quadrature
  Quadrature
  Quadrature may refer to:In signal processing:*Quadrature amplitude modulation , a modulation method of using both an carrier wave and a 'quadrature' carrier wave that is 90° out of phase with the main, or in-phase, carrier...
  
  
• quadrature amplitude modulation
  Quadrature amplitude modulation
  Quadrature amplitude modulation is both an analog and a digital modulation scheme. It conveys two analog message signals, or two digital bit streams, by changing the amplitudes of two carrier waves, using the amplitude-shift keying digital modulation scheme or amplitude modulation analog...
  
  
• quantum optics
  Quantum optics
  Quantum optics is a field of research in physics, dealing with the application of quantum mechanics to phenomena involving light and its interactions with matter.- History of quantum optics :...
  
  
• quantum tunneling
• Quantum Zeno effect
  Quantum Zeno effect
  The quantum Zeno effect is a name coined by George Sudarshan and Baidyanath Misra of the University of Texas in 1977 in their analysis of the situation in which an unstable particle, if observed continuously, will never decay. One can nearly "freeze" the evolution of the system by measuring it...
  
  

R

• radar
  Radar
  Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
  
  
• radar astronomy
  Radar astronomy
  Radar astronomy is a technique of observing nearby astronomical objects by reflecting microwaves off target objects and analyzing the echoes. This research has been conducted for six decades. Radar astronomy differs from radio astronomy in that the latter is a passive observation and the former an...
  
  
• radar cross section
  Radar cross section
  Radar cross section is a measure of how detectable an object is with a radar. A larger RCS indicates that an object is more easily detected.An object reflects a limited amount of radar energy...
  
  
• radar gun
  Radar gun
  A radar speed gun is a small doppler radar unit used to measure the speed of moving objects, including vehicles, pitched baseballs, runners and other moving objects. Radar speed guns may be hand-held, vehicle-mounted or static...
  
  
• radio propagation
  Radio propagation
  Radio propagation is the behavior of radio waves when they are transmitted, or propagated from one point on the Earth to another, or into various parts of the atmosphere...
  
  
• radio waves
  Radio waves
  Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths from 1 millimeter to 100 kilometers. Like all other electromagnetic waves,...
  
  
• Radiosity (heat transfer)
  Radiosity (heat transfer)
  Radiosity is a convenient quantity in optics and heat transfer that represents the total radiation intensity leaving a surface. Radiosity accounts for two components: the radiation being emitted by the surface, and the radiation being reflected from the surface...
  
  
• Rayleigh–Jeans law
• Rayleigh scattering
  Rayleigh scattering
  Rayleigh scattering, named after the British physicist Lord Rayleigh, is the elastic scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the light. The particles may be individual atoms or molecules. It can occur when light travels through...
  
  
• Rayleigh wave
  Rayleigh wave
  Rayleigh waves are a type of surface acoustic wave that travels on solids. They are produced on the Earth by earthquakes, in which case they are also known as "ground roll", or by other sources of seismic energy such as ocean waves an explosion or even a sledgehammer impact...
  
  
• Rayleigh–Jeans law
• redshift
  Redshift
  In physics , redshift happens when light seen coming from an object is proportionally increased in wavelength, or shifted to the red end of the spectrum...
  
  
• reflection coefficient
  Reflection coefficient
  The reflection coefficient is used in physics and electrical engineering when wave propagation in a medium containing discontinuities is considered. A reflection coefficient describes either the amplitude or the intensity of a reflected wave relative to an incident wave...
  
  
• reflection seismology
  Reflection seismology
  Reflection seismology is a method of exploration geophysics that uses the principles of seismology to estimate the properties of the Earth's subsurface from reflected seismic waves. The method requires a controlled seismic source of energy, such as dynamite/Tovex, a specialized air gun or a...
  
  
• refraction
  Refraction
  Refraction is the change in direction of a wave due to a change in its speed. It is essentially a surface phenomenon . The phenomenon is mainly in governance to the law of conservation of energy. The proper explanation would be that due to change of medium, the phase velocity of the wave is changed...
  
  
• relativistic Doppler effect
  Relativistic Doppler effect
  The relativistic Doppler effect is the change in frequency of light, caused by the relative motion of the source and the observer , when taking into account effects described by the special theory of relativity.The relativistic Doppler effect is different from the non-relativistic Doppler effect...
  
  
• resonance
  Resonance
  In physics, resonance is the tendency of a system to oscillate at a greater amplitude at some frequencies than at others. These are known as the system's resonant frequencies...
  
  
• Resonator
  Resonator
  A resonator is a device or system that exhibits resonance or resonant behavior, that is, it naturally oscillates at some frequencies, called its resonant frequencies, with greater amplitude than at others. The oscillations in a resonator can be either electromagnetic or mechanical...
  
  
• Ring laser gyroscope
  Ring laser gyroscope
  A ring laser gyroscope consists of a ring laser having two counter-propagating modes over the same path in order to detect rotation. It operates on the principle of the Sagnac effect which shifts the nulls of the internal standing wave pattern in response to angular rotation...
  
  
• ring modulation
  Ring modulation
  Ring modulation is a signal-processing effect in electronics, an implementation of amplitude modulation or frequency mixing, performed by multiplying two signals, where one is typically a sine-wave or another simple waveform. It is referred to as "ring" modulation because the analog circuit of...
  
  
• ring wave guide
• rip current
  Rip current
  A rip current, commonly referred to by the misnomer rip tide, is a strong channel of water flowing seaward from near the shore, typically through the surf line. Typical flow is at 0.5 metres per second , and can be as fast as 2.5 metres per second...
  
  
• ripple
  Ripple
  Ripple is the more common name for a capillary wave in fluid dynamics.Ripple can also refer to:* Ripple , a non-profit click-to-donate internet site and search engine* Ripple effect, the socio-educational phenomenon...
  
  
• ripple tank
  Ripple tank
  In physics and engineering, a ripple tank is a shallow glass tank of water used in schools and colleges to demonstrate the basic properties of waves. It is a specialized form of a wave tank. The ripple tank is usually illuminated from above, so that the light shines through the water. Some small...
  
  
• rogue wave (oceanography)
• Rossby-gravity waves
  Rossby-gravity waves
  Rossby-gravity waves are equatorially-trapped waves , meaning that they rapidly decay as their distance increases away from the equator . These waves have the same trapping scale as Kelvin waves, more commonly known as the equatorial Rossby deformation radius...
  
  
• Rossby wave
  Rossby wave
  Atmospheric Rossby waves are giant meanders in high-altitude winds that are a major influence on weather.They are not to be confused with oceanic Rossby waves, which move along the thermocline: that is, the boundary between the warm upper layer of the ocean and the cold deeper part of the...
  
  
• Rydberg constant
  Rydberg constant
  The Rydberg constant, symbol R∞, named after the Swedish physicist Johannes Rydberg, is a physical constant relating to atomic spectra in the science of spectroscopy. Rydberg initially determined its value empirically from spectroscopy, but Niels Bohr later showed that its value could be calculated...
  
  
• Rydberg formula
  Rydberg formula
  The Rydberg formula is used in atomic physics to describe the wavelengths of spectral lines of many chemical elements. It was formulated by the Swedish physicist Johannes Rydberg, and presented on November 5, 1888.-History:...
  
  

S

• S-wave
  S-wave
  A type of seismic wave, the S-wave, secondary wave, or shear wave is one of the two main types of elastic body waves, so named because they move through the body of an object, unlike surface waves....
  
  
• sample (signal)
• sawtooth wave
  Sawtooth wave
  The sawtooth wave is a kind of non-sinusoidal waveform. It is named a sawtooth based on its resemblance to the teeth on the blade of a saw....
  
  
• Schrödinger equation
  Schrödinger equation
  The Schrödinger equation was formulated in 1926 by Austrian physicist Erwin Schrödinger. Used in physics , it is an equation that describes how the quantum state of a physical system changes in time....
  
  
• sea state
  Sea state
  In oceanography, a sea state is the general condition of the free surface on a large body of water—with respect to wind waves and swell—at a certain location and moment. A sea state is characterized by statistics, including the wave height, period, and power spectrum. The sea state varies with...
  
  
• seiche
  Seiche
  A seiche is a standing wave in an enclosed or partially enclosed body of water. Seiches and seiche-related phenomena have been observed on lakes, reservoirs, swimming pools, bays, harbors and seas...
  
  
• seismic wave
  Seismic wave
  Seismic waves are waves of energy that travel through the earth, and are a result of an earthquake, explosion, or a volcano that imparts low-frequency acoustic energy. Many other natural and anthropogenic sources create low amplitude waves commonly referred to as ambient vibrations. Seismic waves...
  
  
• seismograph
• seismology
  Seismology
  Seismology is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other planet-like bodies. The field also includes studies of earthquake effects, such as tsunamis as well as diverse seismic sources such as volcanic, tectonic, oceanic,...
  
  
• Sellmeier equation
  Sellmeier equation
  The Sellmeier equation is an empirical relationship between refractive index and wavelength for a particular transparent medium. The equation is used to determine the dispersion of light in the medium....
  
  
• shallow water equations
  Shallow water equations
  The shallow water equations are a set of hyperbolic partial differential equations that describe the flow below a pressure surface in a fluid .The equations are derived from depth-integrating the Navier–Stokes...
  
  
• Shive wave machine
  Shive wave machine
  A Shive wave machine is a device used to demonstrate waves and wave mechanics. The Shive wave machine consists of a set of evenly-spaced horizontal rods all attached to a square wire spine. Displacing a rod on one of the ends will cause a wave to propagate across the machine...
  
  
• shock wave
  Shock wave
  A shock wave is a type of propagating disturbance. Like an ordinary wave, it carries energy and can propagate through a medium or in some cases in the absence of a material medium, through a field such as the electromagnetic field...
  
  
• shortwave
  Shortwave
  Shortwave radio refers to the upper MF and all of the HF portion of the radio spectrum, between 1,800–30,000 kHz. Shortwave radio received its name because the wavelengths in this band are shorter than 200 m which marked the original upper limit of the medium frequency band first used...
  
  
• Signal velocity
  Signal velocity
  The signal velocity is the speed at which a wave carries information. It describes how quickly a message can be communicated between two separated parties...
  
  
• significant wave height
  Significant wave height
  In physical oceanography, the significant wave height is defined traditionally as the mean wave height of the highest third of the waves , but now usually defined as four times the standard deviation of the surface elevation...
  
  
• sine wave
  Sine wave
  The sine wave or sinusoid is a mathematical function that describes a smooth repetitive oscillation. It occurs often in pure mathematics, as well as physics, signal processing, electrical engineering and many other fields...
  
  
• single-sideband modulation
  Single-sideband modulation
  Single-sideband modulation or Single-sideband suppressed-carrier is a refinement of amplitude modulation that more efficiently uses electrical power and bandwidth....
  
  
• Sinusoidal plane-wave solutions of the electromagnetic wave equation
  Sinusoidal plane-wave solutions of the electromagnetic wave equation
  Sinusoidal plane-wave solutions are particular solutions to the electromagnetic wave equation.The general solution of the electromagnetic wave equation in homogeneous, linear, time-independent media can be written as a linear superposition of plane-waves of different frequencies and...
  
  
• skywave
  Skywave
  Skywave is the propagation of electromagnetic waves bent back to the Earth's surface by the ionosphere. As a result of skywave propagation, a broadcast signal from a distant AM broadcasting station at night, or from a shortwave radio station can sometimes be heard as clearly as local...
  
  
• Slow-wave potential
• Slow-wave sleep
  Slow-wave sleep
  Slow-wave sleep , often referred to as deep sleep, consists of stages 3 and 4 of non-rapid eye movement sleep, according to the Rechtschaffen & Kales standard of 1968. As of 2008, the American Academy of Sleep Medicine has discontinued the use of stage 4, such that the previous stages 3 and 4 now...
  
  
• Slow-wave threshold
• Sneaker wave
  Sneaker wave
  Sneaker wave is a popular term used to describe disproportionately large coastal waves that can sometimes appear in a wave train without warning...
  
  
• solitary wave
  Solitary wave
  In mathematics and physics, a solitary wave can refer to* The solitary wave or wave of translation, as observed by John Scott Russell in the Union Canal, near Edinburgh in 1834...
  
  
• soliton
  Soliton
  In mathematics and physics, a soliton is a self-reinforcing solitary wave that maintains its shape while it travels at constant speed. Solitons are caused by a cancellation of nonlinear and dispersive effects in the medium...
  
  
• sonar
  Sonar
  Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...
  
  
• Sonic anemometers
• sound wave
• Spark-gap transmitter
  Spark-gap transmitter
  A spark-gap transmitter is a device for generating radio frequency electromagnetic waves using a spark gap.These devices served as the transmitters for most wireless telegraphy systems for the first three decades of radio and the first demonstrations of practical radio were carried out using them...
  
  
• Spectroscopy
  Spectroscopy
  Spectroscopy is the study of the interaction between matter and radiated energy. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, e.g., by a prism. Later the concept was expanded greatly to comprise any interaction with radiative...
  
  
• Speed of gravity
  Speed of gravity
  In the context of classical theories of gravitation, the speed of gravity is the speed at which changes in a gravitational field propagate. This is the speed at which a change in the distribution of energy and momentum of matter results in subsequent alteration, at a distance, of the gravitational...
  
  
• Speed of light
  Speed of light
  The speed of light in vacuum, usually denoted by c, is a physical constant important in many areas of physics. Its value is 299,792,458 metres per second, a figure that is exact since the length of the metre is defined from this constant and the international standard for time...
  
  
• speed of sound
  Speed of sound
  The speed of sound is the distance travelled during a unit of time by a sound wave propagating through an elastic medium. In dry air at , the speed of sound is . This is , or about one kilometer in three seconds or approximately one mile in five seconds....
  
  
• Spike-and-wave
  Spike-and-wave
  Spike-and-wave is the term that describes a particular pattern of the electroencephalogram typically observed during epileptic seizures. Spike-and-wave patterns are seen in many types of epilepsy, and in particular during absence seizures , which are characterized by clear-cut spike-and-wave EEG...
  
  
• spin wave
  Spin wave
  Spin waves are propagating disturbances in the ordering of magnetic materials. These low-lying collective excitations occur in magnetic lattices with continuous symmetry. From the equivalent quasiparticle point of view, spin waves are known as magnons, which are boson modes of the spin lattice...
  
  
• square wave
  Square wave
  A square wave is a kind of non-sinusoidal waveform, most typically encountered in electronics and signal processing. An ideal square wave alternates regularly and instantaneously between two levels...
  
  
• standing wave
  Standing wave
  In physics, a standing wave – also known as a stationary wave – is a wave that remains in a constant position.This phenomenon can occur because the medium is moving in the opposite direction to the wave, or it can arise in a stationary medium as a result of interference between two waves traveling...
  
  
• standing wave ratio
  Standing wave ratio
  In telecommunications, standing wave ratio is the ratio of the amplitude of a partial standing wave at an antinode to the amplitude at an adjacent node , in an electrical transmission line....
  
  
• Stefan–Boltzmann law
• Stokes drift
  Stokes drift
  For a pure wave motion in fluid dynamics, the Stokes drift velocity is the average velocity when following a specific fluid parcel as it travels with the fluid flow...
  
  
• subharmonic
  Subharmonic
  Subharmonic frequencies are frequencies below the fundamental frequency of an oscillator in a ratio of 1/n, with n a positive integer number. For example, if the fundamental frequency of an oscillator is 440 Hz, sub-harmonics include 220 Hz and 110 Hz...
  
  
• superharmonic
• super low frequency
  Super low frequency
  Super-low frequency is the frequency range between 30 hertz and 300 hertz. This frequency range includes the frequencies of AC power grids ....
  
  
• Superposition principle
  Superposition principle
  In physics and systems theory, the superposition principle , also known as superposition property, states that, for all linear systems, the net response at a given place and time caused by two or more stimuli is the sum of the responses which would have been caused by each stimulus individually...
  
  
• Supersonic Wave Filter
  Supersonic Wave Filter
  The Supersonic Wave Filter is a dust reduction system developed by Olympus to overcome the negative effect of dust particles landing on the image sensor of digital SLRs. DSLRs are particularly vulnerable to this issue, since the interior of the camera is exposed during lens changes unlike other...
  
  
• surface acoustic wave
  Surface acoustic wave
  ]A surface acoustic wave is an acoustic wave traveling along the surface of a material exhibiting elasticity, with an amplitude that typically decays exponentially with depth into the substrate.-Discovery:...
  
  
• Surface wave
  Surface wave
  In physics, a surface wave is a mechanical wave that propagates along the interface between differing media, usually two fluids with different densities. A surface wave can also be an electromagnetic wave guided by a refractive index gradient...
  
  
• Surface wave inversion
  Surface wave inversion
  Inversion is the set of methods used to infer properties through physical measurements. Surface wave inversion is the method by which elastic properties, density, and thickness of layers in the subsurface are attained through analysis of surface wavedispersion...
  
  
• Surface wave magnitude
  Surface wave magnitude
  The surface wave magnitude scale is one of the magnitude scales used in seismology to describe the size of an earthquake. It is based on measurements in Rayleigh surface waves that travel primarily along the uppermost layers of the earth...
  
  
• surface-wave-sustained mode
  Surface-wave-sustained mode
  Plasmas that are excited by propagation of electromagnetic surface waves are called surface-wave-sustained. Surface wave plasma sources can be divided into two groups depending upon whether the plasma generates part of its own waveguide by ionisation or not. The former is called a self-guided plasma...
  
  
• surfing
  Surfing
  Surfing' is a surface water sport in which the surfer rides a surfboard on the crest and face of a wave which is carrying the surfer towards the shore...
  
  
• Sverdrup wave
  Sverdrup wave
  A Sverdrup wave is a wave in the ocean , which is affected by gravity and Earth's rotation...
  
  
• swell (ocean)
  Swell (ocean)
  A swell, in the context of an ocean, sea or lake, is a series surface gravity waves that is not generated by the local wind. Swell waves often have a long wavelength but this varies with the size of the water body, e.g. rarely more than 150 m in the Mediterranean, and from event to event, with...
  
  
• synthetic aperture radar
  Synthetic aperture radar
  Synthetic-aperture radar is a form of radar whose defining characteristic is its use of relative motion between an antenna and its target region to provide distinctive long-term coherent-signal variations that are exploited to obtain finer spatial resolution than is possible with conventional...
  
  

T

• Terrestrial gamma-ray flash
  Terrestrial gamma-ray flash
  Terrestrial gamma-ray flashes are bursts of gamma rays in the Earth's atmosphere. TGFs have been recorded to last 0.2 to 3.5 milliseconds, and have energies of up to 20 MeV. They are probably caused by electric fields produced above thunderstorms...
  
  
• Terrestrial stationary waves
  Terrestrial stationary waves
  Terrestrial stationary waves is a persistent spherical conductor “single-wire” surface wave electrical transmission line phenomenon arising across the Earth's surface by virtue of the highly conductive nature of the earth itself. It was considered by Nikola Tesla to be his most important discovery...
  
  
• theta wave
• tidal bore
  Tidal bore
  A tidal bore is a tidal phenomenon in which the leading edge of the incoming tide forms a wave of water that travel up a river or narrow bay against the direction of the river or bay's current...
  
  
• tidal power
  Tidal power
  Tidal power, also called tidal energy, is a form of hydropower that converts the energy of tides into useful forms of power - mainly electricity....
  
  
• tidal resonance
  Tidal resonance
  In oceanography, a tidal resonance occurs when the tide excites one of the resonant modes of the ocean.The effect is most striking when a continental shelf is about a quarter wavelength wide...
  
  
• tide
  Tide
  Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....
  
  
• tired light theory
• transverse mode
  Transverse mode
  A transverse mode of a beam of electromagnetic radiation is a particular electromagnetic field pattern of radiation measured in a plane perpendicular to the propagation direction of the beam...
  
  
• transverse wave
  Transverse wave
  A transverse wave is a moving wave that consists of oscillations occurring perpendicular to the direction of energy transfer...
  
  
• Traveling wave antenna
  Traveling wave antenna
  Traveling-wave antenna is a class of antenna that use a traveling wave on a guiding structure as the main radiating mechanism. Traveling-wave antennas fall into two general categories: slow-wave antennas and fast-wave antennas, which are...
  
  
• Traveling wave reactor
  Traveling wave reactor
  A traveling-wave reactor, or TWR, is a type of conceptual nuclear reactor that theorists speculate can convert fertile material into fissile fuel as it runs using the process of nuclear transmutation...
  
  
• traveling-wave tube
• triangle wave
  Triangle wave
  A triangle wave is a non-sinusoidal waveform named for its triangular shape.Like a square wave, the triangle wave contains only odd harmonics...
  
  
• trigonometric function
  Trigonometric function
  In mathematics, the trigonometric functions are functions of an angle. They are used to relate the angles of a triangle to the lengths of the sides of a triangle...
  
  
• Trojan wave packet
  Trojan wave packet
  A Trojan wave packet is a wave packet that is nonstationary and nonspreading. It is part of an artificially created system, which consists of a nucleus, and one or more electron wave packets, of a highly excited atom....
  
  
• Tropical wave
  Tropical wave
  Tropical waves, easterly waves, or tropical easterly waves, also known as African easterly waves in the Atlantic region, are a type of atmospheric trough, an elongated area of relatively low air pressure, oriented north to south, which move from east to west across the tropics causing areas of...
  
  
• tsunami
  Tsunami
  A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...
  
  
• Turbidity current
  Turbidity current
  A turbidity current is a current of rapidly moving, sediment-laden water moving down a slope through water, or another fluid. The current moves because it has a higher density and turbidity than the fluid through which it flows...
  
  
• T wave
  T wave
  In electrocardiography, the T wave represents the repolarization of the ventricles. The interval from the beginning of the QRS complex to the apex of the T wave is referred to as the absolute refractory period. The last half of the T wave is referred to as the relative refractory period...
  
  

U

• ultra low frequency
  Ultra low frequency
  Ultra-low frequency is the frequency range of electromagnetic waves between 300 hertz and 3 kilohertz. In magnetosphere science and seismology, alternative definitions are usually given, including ranges from 1 mHz to 100 Hz, 1 mHz to 1 Hz, 10 mHz to 10 Hz...
  
  
• ultrasonic sound waves
• ultrasound
  Ultrasound
  Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
  
  
• ultraviolet catastrophe
  Ultraviolet catastrophe
  The ultraviolet catastrophe, also called the Rayleigh–Jeans catastrophe, was a prediction of late 19th century/early 20th century classical physics that an ideal black body at thermal equilibrium will emit radiation with infinite power....
  
  
• Sneaker wave
  Sneaker wave
  Sneaker wave is a popular term used to describe disproportionately large coastal waves that can sometimes appear in a wave train without warning...
  
  
• Undertow (wave action)
  Undertow (wave action)
  Undertow is a subsurface flow of water returning seaward from shore as result of wave action. This type of shore current can play a role in material deposition such as creating sand bars....
  
  
• undular bore
  Undular bore
  In meteorology, an undular bore is a wave disturbance in the Earth's atmosphere and can be seen through unique cloud formations. They normally occur within an area of the atmosphere which is stable in the low levels after an outflow boundary or a cold front moves through.In hydraulics, an undular...
  
  
• underwater wave

V

• vestigial-sideband modulation
• vibrating string
  Vibrating string
  A vibration in a string is a wave. Usually a vibrating string produces a sound whose frequency in most cases is constant. Therefore, since frequency characterizes the pitch, the sound produced is a constant note....
  
  
• voltage standing wave ratio
• Vortex
  Vortex
  A vortex is a spinning, often turbulent,flow of fluid. Any spiral motion with closed streamlines is vortex flow. The motion of the fluid swirling rapidly around a center is called a vortex...
  
  
• Vorticity

W

• wake
  Wake
  A wake is the region of recirculating flow immediately behind a moving or stationary solid body, caused by the flow of surrounding fluid around the body.-Fluid dynamics:...
  
  
• Waterspout
  Waterspout
  A waterspout is an intense columnar vortex that occurs over a body of water and is connected to a cumuliform cloud. In the common form, it is a non-supercell tornado over water. While it is often weaker than most of its land counterparts, stronger versions spawned by mesocyclones do occur...
  
  
• wave base
  Wave base
  The wave base is the maximum depth at which a water wave's passage causes significant water motion. For water depths larger than the wave base, bottom sediments are no longer stirred by the wave motion above....
  
  
• Wave disk engine
  Wave disk engine
  A wave disk engine is a type of pistonless rotary engine being developed at Michigan State University and Warsaw Institute of Technology. The engine has a spinning disk with curved blades. Once fuel and air enter the engine the rotation of the disk creates shockwaves that compress the mixture...
  
  
• wave drag
  Wave drag
  In aeronautics, wave drag is a component of the drag on aircraft, blade tips and projectiles moving at transonic and supersonic speeds, due to the presence of shock waves. Wave drag is independent of viscous effects.- Overview :...
  
  
• wave equation
  Wave equation
  The wave equation is an important second-order linear partial differential equation for the description of waves – as they occur in physics – such as sound waves, light waves and water waves. It arises in fields like acoustics, electromagnetics, and fluid dynamics...
  
  
• Wave farm
  Wave farm
  A wave farm or wave power farm is a collection of machines in the same location and used for the generation of wave power electricity.-Portugal:...
  
  
• Wave field synthesis
  Wave field synthesis
  Wave field synthesis is a spatial audio rendering technique, characterized by creation of virtual acoustic environments. It produces "artificial" wave fronts synthesized by a large number of individually driven speakers. Such wave fronts seem to originate from a virtual starting point, the virtual...
  
  
• Wave function
• Wave function collapse
• Wave height
  Wave height
  In fluid dynamics, the wave height of a surface wave is the difference between the elevations of a crest and a neighbouring trough. Wave height is a term used by mariners, as well as in coastal, ocean and naval engineering....
  
  
• wave impedance
  Wave impedance
  The wave impedance of an electromagnetic wave is the ratio of the transverse components of the electric and magnetic fields . For a transverse-electric-magnetic plane wave traveling through a homogeneous medium, the wave impedance is everywhere equal to the intrinsic impedance of the medium...
  
  
• Wave loading
  Wave loading
  Wave loading is most commonly the application of a pulsed or wavelike load to a material or object. This is most commonly used in the analysis of piping, ships, or building structures which experience wind, water, or seismic disturbances....
  
  
• wavelength
  Wavelength
  In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
  
  
• Wave making resistance
  Wave making resistance
  Wave making resistance is a form of drag that affects surface watercraft, such as boats and ships, and reflects the energy required to push the water out of the way of the hull. This energy goes into creating the wake.-Physics:...
  
  
• Wave motor
  Wave motor
  Wave motors were machines designed and built in the late 19th and early 20th century to harness the power of wave or tidal energy. Many experiments were planned or built in California employing various methods. The earliest wave motors were not intended for the creation of electricity...
  
  
• Wave packet
  Wave packet
  In physics, a wave packet is a short "burst" or "envelope" of wave action that travels as a unit. A wave packet can be analyzed into, or can be synthesized from, an infinite set of component sinusoidal waves of different wavenumbers, with phases and amplitudes such that they interfere...
  
  
• wave period
• Wave plate
  Wave plate
  A wave plate or retarder is an optical device that alters the polarization state of a light wave travelling through it.- Operation :A wave plate works by shifting the phase between two perpendicular polarization components of the light wave. A typical wave plate is simply a birefringent crystal...
  
  
• Wave pool
  Wave pool
  A wave pool is a swimming pool in which there are artificially generated, reasonably large waves, similar to the ocean's. Wave pools are often a major feature of water parks...
  
  
• Wave pounding
  Wave pounding
  Wave pounding is the 'sledge hammer' effect of tonnes of water crashing against cliffs. It shakes and weakens the rocks leaving them open to attack from hydraulic action and abrasion. Eroded material gets carried away by the wave. Wave Pounding is particularly fierce in a storm, where the waves are...
  
  
• wave power
  Wave power
  Wave power is the transport of energy by ocean surface waves, and the capture of that energy to do useful work — for example, electricity generation, water desalination, or the pumping of water...
  
  
• Wave propagation
  Wave propagation
  Wave propagation is any of the ways in which waves travel.With respect to the direction of the oscillation relative to the propagation direction, we can distinguish between longitudinal wave and transverse waves....
  
  
• Wave propagation speed
• Wave shoaling
  Wave shoaling
  In fluid dynamics, wave shoaling is the effect by which surface waves entering shallower water increase in wave height . It is caused by the fact that the group velocity, which is also the wave-energy transport velocity, decreases with the reduction of water depth...
  
  
• Wave tank
  Wave tank
  A wave tank is a laboratory setup for observing the behavior of surface waves. The typical wave tank is a deep and narrow, transparent-sided box filled with liquid, usually water, leaving open or air-filled space on top. At one end of the tank an actuator generates waves; the other end usually...
  
  
• Wave turbulence
  Wave turbulence
  Wave turbulence is a set of waves deviated far from thermal equilibrium. Such state is accompanied by dissipation. It is either decaying turbulence or requires external source of energy to sustain it...
  
  
• wave vector
  Wave vector
  In physics, a wave vector is a vector which helps describe a wave. Like any vector, it has a magnitude and direction, both of which are important: Its magnitude is either the wavenumber or angular wavenumber of the wave , and its direction is ordinarily the direction of wave propagation In...
  
  
• Wave velocity
  Wave velocity
  Wave velocity is a wave property, which may refer to:*phase velocity, the velocity at which a wave phase propagates at a certain frequency*pulse wave velocity, the velocity at which a pulse travels through a medium, usually applied to arteries as a measure of arterial stiffness*group velocity, the...
  
  
• Wave–current interaction
  Wave–current interaction
  In fluid dynamics, wave–current interaction is the interaction between surface gravity waves and a mean flow. The interaction implies an exchange of energy, so after the start of the interaction both the waves and the mean flow are affected....
  
  
• Wave-cut platform
  Wave-cut platform
  A wave-cut platform, or shore platform is the narrow flat area often found at the base of a sea cliff or along the shoreline of a lake, bay, or sea that was created by the action of waves. Wave-cut platforms are often most obvious at low tide when they become visible as huge areas of flat rock...
  
  
• Wave form
• wave-formed ripple
• waveform monitor
  Waveform monitor
  A waveform monitor is a special type of oscilloscope used in television production applications. It is typically used to measure and display the level, or voltage, of a video signal with respect to time....
  
  
• Wavefront
  Wavefront
  In physics, a wavefront is the locus of points having the same phase. Since infrared, optical, x-ray and gamma-ray frequencies are so high, the temporal component of electromagnetic waves is usually ignored at these wavelengths, and it is only the phase of the spatial oscillation that is described...
  
  
• wavefunction
  Wavefunction
  Not to be confused with the related concept of the Wave equationA wave function or wavefunction is a probability amplitude in quantum mechanics describing the quantum state of a particle and how it behaves. Typically, its values are complex numbers and, for a single particle, it is a function of...
  
  
• wavefunction collapse
  Wavefunction collapse
  In quantum mechanics, wave function collapse is the phenomenon in which a wave function—initially in a superposition of several different possible eigenstates—appears to reduce to a single one of those states after interaction with an observer...
  
  
• waveguide
  Waveguide
  A waveguide is a structure which guides waves, such as electromagnetic waves or sound waves. There are different types of waveguides for each type of wave...
  
  
• Waveguide (acoustics)
  Waveguide (acoustics)
  An acoustic waveguide is a physical structure for guiding sound waves.- Examples :One example might be a speaking tube used aboard ships for communication between decks....
  
  
• Waveguide (electromagnetism)
  Waveguide (electromagnetism)
  In electromagnetics and communications engineering, the term waveguide may refer to any linear structure that conveys electromagnetic waves between its endpoints. However, the original and most common meaning is a hollow metal pipe used to carry radio waves...
  
  
• Waveguide (optics)
  Waveguide (optics)
  An optical waveguide is a physical structure that guides electromagnetic waves in the optical spectrum. Common types of optical waveguides include optical fiber and rectangular waveguides....
  
  
• Waveguide flange
  Waveguide flange
  A waveguide flange is a connector for joining sections of waveguide, and is essentially the same as a pipe flange—a waveguide, in the context of this article, being a hollow metal conduit for microwave energy. The connecting face of the flange is either square, circular or , rectangular...
  
  
• wavelength-division multiplexing
  Wavelength-division multiplexing
  In fiber-optic communications, wavelength-division multiplexing is a technology which multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths of laser light...
  
  
• Wavelength selective switching
  Wavelength selective switching
  Wavelength Selective Switching components are industrial packages integrating devices for wavelength multiplexing/demultiplexing of WDM signals and mechanisms to switch signals on a per-wavelength basis....
  
  
• Wavelet
  Wavelet
  A wavelet is a wave-like oscillation with an amplitude that starts out at zero, increases, and then decreases back to zero. It can typically be visualized as a "brief oscillation" like one might see recorded by a seismograph or heart monitor. Generally, wavelets are purposefully crafted to have...
  
  
• Wavelet transform
• wavenumber
  Wavenumber
  In the physical sciences, the wavenumber is a property of a wave, its spatial frequency, that is proportional to the reciprocal of the wavelength. It is also the magnitude of the wave vector...
  
  
• wavenumber-frequency diagram
  Wavenumber-frequency diagram
  A wavenumber–frequency diagram is a plot displaying the relationship between the wavenumber and the frequency of certain phenomena...
  
  
• Wave–current interaction
  Wave–current interaction
  In fluid dynamics, wave–current interaction is the interaction between surface gravity waves and a mean flow. The interaction implies an exchange of energy, so after the start of the interaction both the waves and the mean flow are affected....
  
  
• wave–particle duality
  Wave–particle duality
  Wave–particle duality postulates that all particles exhibit both wave and particle properties. A central concept of quantum mechanics, this duality addresses the inability of classical concepts like "particle" and "wave" to fully describe the behavior of quantum-scale objects...
  
  
• waverider
  Waverider
  A waverider is a hypersonic aircraft design that improves its supersonic lift-to-drag ratio by using the shock waves being generated by its own flight as a lifting surface. To date the only aircraft to use the technique is the Mach 3 supersonic XB-70 Valkyrie, which was waverider-like with its...
  
  
• waves and shallow water
  Waves and shallow water
  When waves travel into areas of shallow water, they begin to be affected by the ocean bottom. The free orbital motion of the water is disrupted, and water particles in orbital motion no longer return to their original position. As the water becomes shallower, the swell becomes higher and steeper,...
  
  
• waves in plasmas
  Waves in plasmas
  Waves in plasmas are an interconnected set of particles and fields which propagates in a periodically repeating fashion. A plasma is a quasineutral, electrically conductive fluid. In the simplest case, it is composed of electrons and a single species of positive ions, but it may also contain...
  
  
• Wien approximation
• Wien's displacement law
  Wien's displacement law
  Wien's displacement law states that the wavelength distribution of thermal radiation from a black body at any temperature has essentially the same shape as the distribution at any other temperature, except that each wavelength is displaced on the graph...
  
  
• Wien's law
  Wien's law
  Wien's law or Wien law may refer to:* Wien approximation, an equation used to describe the short-wavelength spectrum of thermal radiation....
  
  
• Windsurfing
  Windsurfing
  Windsurfing or sailboarding is a surface water sport that combines elements of surfing and sailing. It consists of a board usually two to four metres long, powered by the orthogonal effect of the wind on a sail. The rig is connected to the board by a free-rotating universal joint and comprises a...
  
  
• Wind wave

Z

• zero-dispersion slope
• zero-dispersion wavelength
  Zero-dispersion wavelength
  In a single-mode optical fiber, the zero-dispersion wavelength is the wavelength or wavelengths at which material dispersion and waveguide dispersion cancel one another. In all silica-based optical fibers, minimum material dispersion occurs naturally at a wavelength of approximately 1300nm...
  
  
• zigzag
  Zigzag
  A zigzag is a pattern made up of small corners at variable angles, though constant within the zigzag, tracing a path between two parallel lines; it can be described as both jagged and fairly regular....
  
  
• Zodiacal light
  Zodiacal light
  Zodiacal light is a faint, roughly triangular, whitish glow seen in the night sky which appears to extend up from the vicinity of the sun along the ecliptic or zodiac. Caused by sunlight scattered by space dust in the zodiacal cloud, it is so faint that either moonlight or light pollution renders...
  
  
• zone plate
  Zone plate
  A zone plate is a device used to focus light or other things exhibiting wave character. Unlike lenses or curved mirrors however, zone plates use diffraction instead of refraction or reflection. Based on analysis by Augustin-Jean Fresnel, they are sometimes called Fresnel zone plates in his honor...