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Dewbow
A dewbow is an optical effect, similar to a rainbow, where dewdrops instead of rain droplets reflect and disperse sunlight. Occurrence Dewbows can be seen on fields covered with dew, when the sun shines. Dew forms outdoors in the early morning after a clear night, when the surface temperature drops below the dew point. It forms most easily on surfaces that are isolated from conducted heat from deep ground, such as grass, leaves, and spider webs. Dew bows will be clearest on fields littered with cobwebs, as may occur in autumn. Shape A ''rainbow'' is perceived as a circle in the sky; and its contributing light rays form a cone. In contrast, a ''dewbow'' is perceived as the intersection of that cone and the ground. If the ground is flat and horizontal, and the sun is low in the sky, the dew bow is a hyperbola. Theoretically, when the sun is high, the intersection might be another conic section, like a parabola or an ellipse. However, dew usually evaporates before the sun is high ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fogbow
A fog bow, sometimes called a white rainbow, is a similar phenomenon to a rainbow; however, as its name suggests, it appears as a bow in fog rather than rain. Because of the very small size of water droplets that cause fog—smaller than —the fog bow has only very weak colors, with a red outer edge and bluish inner edge. The colors fade due to being smeared out by the diffraction effect of the smaller droplets. In many cases, when the droplets are very small, fog bows appear white, and are therefore sometimes called ''white rainbows''. Along with its larger angular size, this lack of color is a feature of a fog bow that distinguishes it from a glory, which has multiple pale-colored rings caused by diffraction. When droplets forming it are almost all of the same size, the fog bow can have multiple inner rings, or supernumeraries, which are more strongly colored than the main bow. A fog bow seen in clouds, typically from an aircraft looking downwards, is called a ''cloud bow' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terrestrial Rainbow
Terrestrial refers to things related to land or the planet Earth, as opposed to extraterrestrial. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on or near the ground, as opposed to arboreal life (in trees) ** A fishing fly that simulates the appearance of a land insect is referred to as a terrestrial fly. * Terrestrial ecoregion, land ecoregions, as distinct from freshwater ecoregions and marine ecoregions * Terrestrial ecosystem, an ecosystem found only on landforms * Terrestrial gamma-ray flash, a burst of gamma rays produced in Earth's atmosphere * Terrestrial locomotion, evolutionary adaptation from aquatic types of locomotion * Terrestrial plant, a plant that grows on land rather than in water or on rocks or trees * Terrestrial planet, a planet that is primarily composed of silicate rocks, and thus "Earth-like" * Terrestrial radio, radio signals received through a conventional a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Effect
Compositing is the process or technique of combining visual elements from separate sources into single images, often to create the illusion that all those elements are parts of the same scene. Live-action shooting for compositing is variously called "chroma key", "blue screen", "green screen" and other names. Today, most compositing is achieved through digital image manipulation. Pre-digital compositing techniques, however, go back as far as the trick films of Georges Méliès in the late 19th century, and some are still in use. Basic procedure All compositing involves the replacement of selected parts of an image with other material, usually, but not always, from another image. In the digital method of compositing, software commands designate a narrowly defined color as the part of an image to be replaced. Then the software (e.g. Natron) replaces every pixel within the designated color range with a pixel from another image, aligned to appear as part of the original. For ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rainbow
A rainbow is an optical phenomenon caused by refraction, internal reflection and dispersion of light in water droplets resulting in a continuous spectrum of light appearing in the sky. The rainbow takes the form of a multicoloured circular arc. Rainbows caused by sunlight always appear in the section of sky directly opposite the Sun. Rainbows can be caused by many forms of airborne water. These include not only rain, but also mist, spray, and airborne dew. Rainbows can be full circles. However, the observer normally sees only an arc formed by illuminated droplets above the ground, and centered on a line from the Sun to the observer's eye. In a primary rainbow, the arc shows red on the outer part and violet on the inner side. This rainbow is caused by light being refracted when entering a droplet of water, then reflected inside on the back of the droplet and refracted again when leaving it. In a double rainbow, a second arc is seen outside the primary arc, and has the or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dew Point
The dew point is the temperature the air needs to be cooled to (at constant pressure) in order to produce a relative humidity of 100%. This temperature depends on the pressure and water content of the air. When the air at a temperature above the dewpoint is cooled, its moisture capacity is reduced and airborne water vapor will Condensation, condense to form liquid water known as dew. When this occurs through the air's contact with a colder surface, dew will form on that surface. The dew point is affected by the air's humidity. The more moisture the air contains, the higher its dew point. When the temperature is below the freezing point of water, the dew point is called the frost point, as frost is formed via deposition (phase transition), deposition rather than condensation. In liquids, the analog to the dew point is the cloud point. Humidity If all the other factors influencing humidity remain constant, at ground level the relative humidity rises as the temperature falls; this ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyperbola
In mathematics, a hyperbola is a type of smooth function, smooth plane curve, curve lying in a plane, defined by its geometric properties or by equations for which it is the solution set. A hyperbola has two pieces, called connected component (topology), connected components or branches, that are mirror images of each other and resemble two infinite bow (weapon), bows. The hyperbola is one of the three kinds of conic section, formed by the intersection of a plane (mathematics), plane and a double cone (geometry), cone. (The other conic sections are the parabola and the ellipse. A circle is a special case of an ellipse.) If the plane intersects both halves of the double cone but does not pass through the apex of the cones, then the conic is a hyperbola. Besides being a conic section, a hyperbola can arise as the locus (mathematics), locus of points whose difference of distances to two fixed focus (geometry), foci is constant, as a curve for each point of which the rays to two fix ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conic Section
A conic section, conic or a quadratic curve is a curve obtained from a cone's surface intersecting a plane. The three types of conic section are the hyperbola, the parabola, and the ellipse; the circle is a special case of the ellipse, though it was sometimes considered a fourth type. The ancient Greek mathematicians studied conic sections, culminating around 200 BC with Apollonius of Perga's systematic work on their properties. The conic sections in the Euclidean plane have various distinguishing properties, many of which can be used as alternative definitions. One such property defines a non-circular conic to be the set of those points whose distances to some particular point, called a '' focus'', and some particular line, called a ''directrix'', are in a fixed ratio, called the ''eccentricity''. The type of conic is determined by the value of the eccentricity. In analytic geometry, a conic may be defined as a plane algebraic curve of degree 2; that is, as the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parabola
In mathematics, a parabola is a plane curve which is Reflection symmetry, mirror-symmetrical and is approximately U-shaped. It fits several superficially different Mathematics, mathematical descriptions, which can all be proved to define exactly the same curves. One description of a parabola involves a Point (geometry), point (the Focus (geometry), focus) and a Line (geometry), line (the Directrix (conic section), directrix). The focus does not lie on the directrix. The parabola is the locus (mathematics), locus of points in that plane that are equidistant from the directrix and the focus. Another description of a parabola is as a conic section, created from the intersection of a right circular conical surface and a plane (geometry), plane Parallel (geometry), parallel to another plane that is tangential to the conical surface. The graph of a function, graph of a quadratic function y=ax^2+bx+ c (with a\neq 0 ) is a parabola with its axis parallel to the -axis. Conversely, every ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ellipse
In mathematics, an ellipse is a plane curve surrounding two focus (geometry), focal points, such that for all points on the curve, the sum of the two distances to the focal points is a constant. It generalizes a circle, which is the special type of ellipse in which the two focal points are the same. The elongation of an ellipse is measured by its eccentricity (mathematics), eccentricity e, a number ranging from e = 0 (the Limiting case (mathematics), limiting case of a circle) to e = 1 (the limiting case of infinite elongation, no longer an ellipse but a parabola). An ellipse has a simple algebraic solution for its area, but for Perimeter of an ellipse, its perimeter (also known as circumference), Integral, integration is required to obtain an exact solution. The largest and smallest diameters of an ellipse, also known as its width and height, are typically denoted and . An ellipse has four extreme points: two ''Vertex (geometry), vertices'' at the endpoints of the major axis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moonbow
A moonbow (also known as a moon rainbow or lunar rainbow) is a rainbow produced by moonlight rather than direct sunlight. Other than the difference in the light source, its formation is the same as for a solar rainbow: It is caused by the refraction of light in many water droplets, such as a rain shower or a waterfall, and is always positioned in the opposite part of the sky from the Moon relative to the observer. Moonbows are much fainter than solar rainbows, due to the smaller amount of light reflected from the surface of the Moon. Because the light is usually too faint to excite the Cone cell, cone color receptors in human eyes, it is difficult for the human eye to discern colors in a moonbow. As a result, a moonbow often appears to be white. However, the colors in a moonbow do appear in Long-exposure photography, long exposure photographs. Moonbows have been mentioned at least since Aristotle, Aristotle's Meteorology (Aristotle), ''Meteorology'' (circa 350 BC). Viewing Moon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atmospheric Optical Phenomena
Atmospheric optical phenomena include: *Afterglow *Airglow * Alexander's band, the dark region between the two bows of a double rainbow. * Alpenglow * Anthelion * Anticrepuscular rays *Aurora (northern and southern lights, aurora borealis and aurora australis) * Belt of Venus * Brocken Spectre * Circumhorizontal arc * Circumzenithal arc *Cloud iridescence *Crepuscular rays *Earth's shadow * Earthquake lights * Glories * Green flash * Halos, of Sun or Moon, including sun dogs * Haze * Heiligenschein or halo effect, partly caused by the opposition effect * Ice blink *Light pillar *Lightning *Mirages (including Fata Morgana) * Monochrome Rainbow * Moon dog *Moonbow * Nacreous cloud/Polar stratospheric cloud *Rainbow *Sprite (lightning) * Subsun *Sun dog * Tangent arc *Tyndall effect * Upper-atmospheric lightning, including red sprites, Blue jets, and ELVES * Water sky See also References {{reflist * atmospheric optical phenomena Optical phenomena Optical phenomena ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
