Optical phenomena are any observable events that result from the interaction of

light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 tera ...

and

matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic partic ...

. All optical phenomena coincide with

quantum In physics, a quantum (plural quanta) is the minimum amount of any physical entity (physical property) involved in an interaction. The fundamental notion that a physical property can be "quantized" is referred to as "the hypothesis of quantizati ...

phenomena. Common optical phenomena are often due to the interaction of light from the sun or moon with the atmosphere, clouds, water, dust, and other particulates. One common example is the rainbow, when light from the sun is reflected and refracted by water droplets. Some phenomena, such as the

green ray The green flash and green ray are meteorological optical phenomena that sometimes occur transiently around the moment of sunset or sunrise. When the conditions are right, a distinct green spot is briefly visible above the Sun's upper lim ...

, are so rare they are sometimes thought to be mythical. Others, such as Fata Morganas, are commonplace in favored locations. Other phenomena are simply interesting aspects of

optics Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviole ...

, or optical effects. For instance, the colors generated by a

prism Prism usually refers to: * Prism (optics), a transparent optical component with flat surfaces that refract light * Prism (geometry), a kind of polyhedron Prism may also refer to: Science and mathematics * Prism (geology), a type of sedimentary ...

are often shown in classrooms. SunHaloOverGoldenBay4thFeb06

List

Optical phenomena include those arising from the optical properties of the

atmosphere An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...

; the rest of nature (other phenomena); of

objects Object may refer to: General meanings * Object (philosophy), a thing, being, or concept ** Object (abstract), an object which does not exist at any particular time or place ** Physical object, an identifiable collection of matter * Goal, an ...

, whether natural or human-made (optical effects); and of our

eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...

s (Entoptic phenomena). Also listed here are unexplained phenomena that could have an optical explanation and "

optical illusion Within visual perception, an optical illusion (also called a visual illusion) is an illusion caused by the visual system and characterized by a visual perception, percept that arguably appears to differ from reality. Illusions come in a wide v ...

s" for which optical explanations have been excluded. There are many phenomena that result from either the

particle In the Outline of physical science, physical sciences, a particle (or corpuscule in older texts) is a small wikt:local, localized physical body, object which can be described by several physical property, physical or chemical property, chemical ...

or the

wave In physics, mathematics, and related fields, a wave is a propagating dynamic disturbance (change from equilibrium) of one or more quantities. Waves can be periodic, in which case those quantities oscillate repeatedly about an equilibrium (res ...

nature of light. Some are quite subtle and observable only by precise measurement using scientific instruments. One famous observation is of the bending of light from a star by the Sun observed during a solar eclipse. This demonstrates that

space Space is the boundless three-dimensional extent in which objects and events have relative position and direction. In classical physics, physical space is often conceived in three linear dimensions, although modern physicists usually consider ...

is curved, as the

theory of relativity The theory of relativity usually encompasses two interrelated theories by Albert Einstein: special relativity and general relativity, proposed and published in 1905 and 1915, respectively. Special relativity applies to all physical phenomena in ...

predicts.

Atmospheric optical phenomena

* Afterglow * Airglow * Alexander's band, the dark region between the two bows of a double rainbow. *

Alpenglow Alpenglow (from german: Alpenglühen, lit=Alps glow; it, enrosadira) is an optical phenomenon that appears as a horizontal reddish glow near the horizon opposite to the Sun when the solar disk is just below the horizon. Description Strictl ...

* Anticrepuscular rays * Anthelion * Auroral light (northern and southern lights, aurora borealis and aurora australis) * Belt of Venus *

Brocken Spectre A Brocken spectre (British English; American spelling Brocken specter; german: Brockengespenst), also called Brocken bow, mountain spectre, or spectre of the Brocken is the magnified (and apparently enormous) shadow of an observer cast in mid ai ...

* Circumhorizontal arc *

Circumzenithal arc The circumzenithal arc, also called the circumzenith arc (CZA), upside-down rainbow, and the Bravais arc,"Mémoire sur les halos et les phénomènes optiques qui les accompagnent", J. de l' École Royale Polytechnique 31(18), 1-270, A. Bravais, ...

* Cloud iridescence * Crepuscular rays *

Earth's shadow Earth's shadow (or Earth shadow) is the shadow that Earth itself casts through its atmosphere and into outer space, toward the antisolar point. During the twilight period (both early dusk and late dawn), the shadow's visible fringe – sometimes ...

Earthquake light An earthquake light is a luminous aerial phenomenon that reportedly appears in the sky at or near areas of tectonic stress, seismic activity, or volcanic eruptions. There is no broad consensus as to the causes of the phenomenon (or phenomena) inv ...

s * Glories * Green flash * Halos, of Sun or Moon, including

sun dog A sun dog (or sundog) or mock sun, also called a parhelion (plural parhelia) in meteorology, is an atmospheric optical phenomenon that consists of a bright spot to one or both sides of the Sun. Two sun dogs often flank the Sun within a 22° ...

s * Heiligenschein or halo effect, partly caused by the

opposition effect The opposition surge (sometimes known as the opposition effect, opposition spike or Seeliger effect) is the brightening of a rough surface, or an object with many particles, when illuminated from directly behind the observer. The term is most wid ...

Light pillar A light pillar is an atmospheric optical phenomenon in which a vertical beam of light appears to extend above and/or below a light source. The effect is created by the reflection of light from tiny ice crystals that are suspended in the atmosp ...

Mirage A mirage is a naturally-occurring optical phenomenon in which light rays bend via refraction to produce a displaced image of distant objects or the sky. The word comes to English via the French ''(se) mirer'', from the Latin ''mirari'', meanin ...

s (including Fata Morgana) * Rainbows *

Subsun A subsun (also spelled sub-sun) is an optical phenomenon that appears as a glowing spot visible within clouds or mist when observed from above. The subsun appears directly below the actual Sun, and is caused by sunlight reflecting off of numer ...

Tyndall effect The Tyndall effect is light scattering by particles in a colloid or in a very fine suspension. Also known as Tyndall scattering, it is similar to Rayleigh scattering, in that the intensity of the scattered light is inversely proportional to the ...

Other optical phenomena

Dichromatism Dichromatism (or polychromatism) is a phenomenon where a material or solution's hue is dependent on both the concentration of the absorbing substance and the depth or thickness of the medium traversed. In most substances which are not dichromatic, ...

Gegenschein Gegenschein (; ; ) or counterglow is a faintly bright spot in the night sky centered at the antisolar point. The backscatter of sunlight by interplanetary dust causes this optical phenomenon. Explanation Like zodiacal light, gegenschein is su ...

Iridescence Iridescence (also known as goniochromism) is the phenomenon of certain surfaces that appear to gradually change color as the angle of view or the angle of illumination changes. Examples of iridescence include soap bubbles, feathers, butterfl ...

Opposition effect The opposition surge (sometimes known as the opposition effect, opposition spike or Seeliger effect) is the brightening of a rough surface, or an object with many particles, when illuminated from directly behind the observer. The term is most wid ...

Shadow A shadow is a dark area where light from a light source is blocked by an opaque object. It occupies all of the three-dimensional volume behind an object with light in front of it. The cross section of a shadow is a two-dimensional silhouette, o ...

** Shade ** Silhouette *

Sylvanshine Sylvanshine is an optical phenomenon in which dew-covered foliage with wax-coated leaves retroreflect beams of light, as from a vehicle's headlights. This effect sometimes makes trees appear snow-covered at night during the summer. The phenomenon w ...

Zodiacal light The zodiacal light (also called false dawn when seen before sunrise) is a faint glow of diffuse sunlight scattered by interplanetary dust. Brighter around the Sun, it appears in a particularly dark night sky to extend from the Sun's direction in ...

Optical effects

* Asterism, star

gems Gems, or gemstones, are polished, cut stones or minerals. Gems or GEMS may also refer to: Arts, entertainment and media *Gems (Aerosmith album), ''Gems'' (Aerosmith album), 1988 *Gems (Patti LaBelle album), ''Gems'' (Patti LaBelle album), 1994 *G ...

such as star

sapphire Sapphire is a precious gemstone, a variety of the mineral corundum, consisting of aluminium oxide () with trace amounts of elements such as iron, titanium, chromium, vanadium, or magnesium. The name sapphire is derived via the Latin "sapphir ...

or star

ruby A ruby is a pinkish red to blood-red colored gemstone, a variety of the mineral corundum ( aluminium oxide). Ruby is one of the most popular traditional jewelry gems and is very durable. Other varieties of gem-quality corundum are called sa ...

Aura Aura most commonly refers to: * Aura (paranormal), a field of luminous multicolored radiation around a person or object * Aura (symptom), a symptom experienced before a migraine or seizure Aura may also refer to: Places Extraterrestrial * 1488 ...

, a phenomenon in which gas or dust surrounding an object luminesces or reflects light from the object * Aventurescence, also called the Schiller effect, spangled gems such as

aventurine quartz Aventurine is a form of quartz, characterised by its translucency and the presence of ped, platy mineral inclusion (mineral), inclusions that give it a shimmering or glistening effect termed ''aventurescence''. Background The most common color of ...

and sunstone * Baily's beads, grains of sunlight visible in total solar eclipses. * camera obscura *

Cathodoluminescence Cathodoluminescence is an optical and electromagnetic phenomenon in which electrons impacting on a luminescent material such as a phosphor, cause the emission of photons which may have wavelengths in the visible spectrum. A familiar example is th ...

* Caustics * Chatoyancy, cat's eye gems such as chrysoberyl cat's eye or aquamarine cat's eye *

Chromatic polarization A Fresnel rhomb is an optical prism that introduces a 90° phase difference between two perpendicular components of polarization, by means of two total internal reflections. If the incident beam is linearly polarized at 45° to the plane of inci ...

Diffraction Diffraction is defined as the interference or bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow of the obstacle/aperture. The diffracting object or aperture effectively becomes a s ...

, the apparent bending and spreading of light

s when they meet an obstruction *

Dispersion Dispersion may refer to: Economics and finance *Dispersion (finance), a measure for the statistical distribution of portfolio returns *Price dispersion, a variation in prices across sellers of the same item *Wage dispersion, the amount of variatio ...

* Double refraction or

birefringence Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. These optically anisotropic materials are said to be birefringent (or birefractive). The birefring ...

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

and other minerals *

Double-slit experiment In modern physics, the double-slit experiment is a demonstration that light and matter can display characteristics of both classically defined waves and particles; moreover, it displays the fundamentally probabilistic nature of quantum mechanics ...

Electroluminescence Electroluminescence (EL) is an optical phenomenon, optical and electrical phenomenon, in which a material emits light in response to the passage of an electric current or to a strong electric field. This is distinct from black body light emissi ...

Evanescent wave In electromagnetics, an evanescent field, or evanescent wave, is an oscillating electric and/or magnetic field that does not propagate as an electromagnetic wave but whose energy is spatially concentrated in the vicinity of the source (oscillati ...

Fluorescence Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, tha ...

, also called luminescence or

photoluminescence Photoluminescence (abbreviated as PL) is light emission from any form of matter after the absorption of photons (electromagnetic radiation). It is one of many forms of luminescence (light emission) and is initiated by photoexcitation (i.e. photon ...

Mie scattering The Mie solution to Maxwell's equations (also known as the Lorenz–Mie solution, the Lorenz–Mie–Debye solution or Mie scattering) describes the scattering of an electromagnetic plane wave by a homogeneous sphere. The solution takes the f ...

(Why clouds are white) * Metamerism as of

alexandrite The mineral or gemstone chrysoberyl is an aluminate of beryllium with the formula Be Al2 O4. The name chrysoberyl is derived from the Greek words χρυσός ''chrysos'' and βήρυλλος ''beryllos'', meaning "a gold-white spar". Despite ...

* Moiré pattern *

Newton's rings Newton's rings is a phenomenon in which an interference pattern is created by the reflection of light between two surfaces, typically a spherical surface and an adjacent touching flat surface. It is named after Isaac Newton, who investigated the ...

Phosphorescence Phosphorescence is a type of photoluminescence related to fluorescence. When exposed to light (radiation) of a shorter wavelength, a phosphorescent substance will glow, absorbing the light and reemitting it at a longer wavelength. Unlike fluo ...

* Pleochroism gems or

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

s, which seem "many-colored" *

Polarized light Polarization (also polarisation) is a property applying to transverse waves that specifies the geometrical orientation of the oscillations. In a transverse wave, the direction of the oscillation is perpendicular to the direction of motion of the ...

-related phenomena such as double refraction, or

Haidinger's brush Haidinger's brush, more commonly known as Haidinger's brushes is an image produced by the eye, an entoptic phenomenon, first described by Austrian physicist Wilhelm Karl von Haidinger in 1844. Haidinger saw it when he looked through various mine ...

* Rayleigh scattering (Why the sky is blue, sunsets are red, and associated phenomena) * Reflection *

Refraction In physics, refraction is the redirection of a wave as it passes from one medium to another. The redirection can be caused by the wave's change in speed or by a change in the medium. Refraction of light is the most commonly observed phenomeno ...

Sonoluminescence Sonoluminescence is the emission of light from imploding bubbles in a liquid when excited by sound. History The sonoluminescence effect was first discovered at the University of Cologne in 1934 as a result of work on sonar. Hermann Frenzel and ...

** Shrimpoluminescence *

Synchrotron radiation Synchrotron radiation (also known as magnetobremsstrahlung radiation) is the electromagnetic radiation emitted when relativistic charged particles are subject to an acceleration perpendicular to their velocity (). It is produced artificially in ...

*The separation of light into colors by a

Triboluminescence Triboluminescence is a phenomenon in which light is generated when a material is mechanically pulled apart, ripped, scratched, crushed, or rubbed (see tribology). The phenomenon is not fully understood, but appears to be caused by the separation a ...

* Thomson scattering *

Total internal reflection Total internal reflection (TIR) is the optical phenomenon in which waves arriving at the interface (boundary) from one medium to another (e.g., from water to air) are not refracted into the second ("external") medium, but completely reflected b ...

* Twisted light *

Umov effect The Umov effect, also known as Umov's law, is a relationship between the albedo of an astronomical object, and the degree of polarization of light reflecting off it. The effect was discovered by the Russian physicist Nikolay Umov in 1905, and can ...

Zeeman effect The Zeeman effect (; ) is the effect of splitting of a spectral line into several components in the presence of a static magnetic field. It is named after the Dutch physicist Pieter Zeeman, who discovered it in 1896 and received a Nobel prize ...

*The ability of light to travel through space or through a vacuum.

Entoptic phenomena

of light through the

eyelash An eyelash (also called lash) (Latin: ''Cilia'') is one of the hairs that grows at the edge of the eyelids. It grows in one layer on the edge of the upper and lower eyelids. Eyelashes protect the eye from debris, dust, and small particles and p ...

es *

* Monocular diplopia (or polyplopia) from reflections at boundaries between the various

ocular media Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...

Phosphene A phosphene is the phenomenon of seeing light without light entering the eye. The word ''phosphene'' comes from the Greek words ''phos'' (light) and ''phainein'' (to show). Phosphenes that are induced by movement or sound may be associated wit ...

s from stimulation other than by light (e.g., mechanical, electrical) of the

rod cell Rod cells are photoreceptor cells in the retina of the eye that can function in lower light better than the other type of visual photoreceptor, cone cells. Rods are usually found concentrated at the outer edges of the retina and are used in per ...

s and cones of the eye or of other neurons of the visual system *

Purkinje images Purkinje images are reflections of objects from the structure of the eye. They are also known as Purkinje reflexes and as Purkinje–Sanson images. At least four Purkinje images are usually visible. The first Purkinje image (P1) is the reflectio ...

Optical illusions

*The unusually large size of the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

as it rises and sets, the moon illusion *The shape of the sky, the sky bowl

Unexplained phenomena

Some phenomena are yet to be conclusively explained and may possibly be some form of optical phenomena. Some consider many of these "mysteries" to simply be local

tourist attraction A tourist attraction is a place of interest that tourists visit, typically for its inherent or an exhibited natural or cultural value, historical significance, natural or built beauty, offering leisure and amusement. Types Places of natural b ...

s that are not worthy of thorough investigation. *

Hessdalen lights The Hessdalen lights are unidentified lights observed in a stretch of the Hessdalen valley in rural central Norway. Background The Hessdalen lights are of unknown origin. They appear both by day and by night, and seem to float through and above ...

Min Min light Min Min is a light phenomenon that has often been reported in outback Australia. History Stories about the lights can be found in several Aboriginal Australian cultures predating the European colonisation of Australia, and have since become ...

s *

Light of Saratoga The Light of Saratoga is a legend located in the Big Thicket of Southeast Texas. This legend of a mysterious light is also known as the Ghost Road of Saratoga, the Saratoga Light, and Bragg Light by local residents. Located on a dirt road, it is a l ...

* Naga fireballs

List

Atmospheric optical phenomena

Other optical phenomena

Optical effects

Entoptic phenomena

Optical illusions

Unexplained phenomena

See also

References

Source

Further reading

External links