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Alexander's Band
Alexander's band or Alexander's dark band is an optical phenomenon associated with rainbows which was named after Alexander of Aphrodisias who first described this phenomenon in Aphrodisias, ''Commentary on Book IV of Aristotle's'' Meteorology (also known as: ''Commentary on Book IV of Aristotle's'' De Meteorologica or ''On Aristotle's'' Meteorology 4), commentary 41. The dark band occurs due to the deviation angles of the primary and secondary rainbows. Both bows exist due to an optical effect called the angle of minimum deviation. The refractive index of water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ... prevents light from being deviated at smaller angles. The minimum deviation angle for the primary bow is 137.5°. Light can be deviated up to 180°, causing it to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alexanders Band Gnangarra
''Smyrnium olusatrum'', common name alexanders (or alisander) is an edible flowering plant of the family Apiaceae (Umbelliferae), which grows on waste ground and in hedges around the Mediterranean and Atlantic coastal regions of Europe. It was formerly widely grown as a pot herb, but is now appreciated mostly by foragers. Description Alexanders is a stout, glabrous (hairless) biennial growing to 150 (sometimes 180) cm tall, with a solid stem up to 22 mm in diameter, which becomes hollow and grooved with age. It has a tuberous tap-root which can be 60 cm long, as well as fibrous lateral roots. The stem leaves are arranged in a spiral (although the upper cauline ones are often opposite and sometimes in whorls of 3), with an inflated, purple-striped, fleshy petiole that has papery margins towards the base. The compound leaves are broadly diamond-shaped, 2- or 3-times ternately (sometimes pinnately) divided. Sometimes they are slightly hairy towards the base. The individual leaf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alexander's Band
Alexander's band or Alexander's dark band is an optical phenomenon associated with rainbows which was named after Alexander of Aphrodisias who first described this phenomenon in Aphrodisias, ''Commentary on Book IV of Aristotle's'' Meteorology (also known as: ''Commentary on Book IV of Aristotle's'' De Meteorologica or ''On Aristotle's'' Meteorology 4), commentary 41. The dark band occurs due to the deviation angles of the primary and secondary rainbows. Both bows exist due to an optical effect called the angle of minimum deviation. The refractive index of water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ... prevents light from being deviated at smaller angles. The minimum deviation angle for the primary bow is 137.5°. Light can be deviated up to 180°, causing it to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Phenomenon
Optical phenomena are any observable events that result from the interaction of light and matter. All optical phenomena coincide with quantum 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, 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, or optical effects. For instance, the colors generated by a prism are often shown in classrooms. List Optical phenomena include those arising from the optical properties of the atmosphere; the rest of nature (other phenomena); of objects, whether natural or human-made (optical effects); and of our eyes (Entoptic phenomena). Also listed here are unexpla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rainbow
A rainbow is a meteorological phenomenon that is caused by reflection, refraction and dispersion of light in water droplets resulting in a spectrum of light appearing in the sky. It 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 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 order of its colours reversed, with red on the inner side of the arc. This is caused by the light being reflected twice on the inside of the d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alexander Of Aphrodisias
Alexander of Aphrodisias ( grc-gre, Ἀλέξανδρος ὁ Ἀφροδισιεύς, translit=Alexandros ho Aphrodisieus; AD) was a Peripatetic philosopher and the most celebrated of the Ancient Greek commentators on the writings of Aristotle. He was a native of Aphrodisias in Caria, and lived and taught in Athens at the beginning of the 3rd century, where he held a position as head of the Peripatetic school. He wrote many commentaries on the works of Aristotle, extant are those on the '' Prior Analytics'', ''Topics'', ''Meteorology'', '' Sense and Sensibilia'', and ''Metaphysics''. Several original treatises also survive, and include a work ''On Fate'', in which he argues against the Stoic doctrine of necessity; and one ''On the Soul''. His commentaries on Aristotle were considered so useful that he was styled, by way of pre-eminence, "the commentator" (). Life and career Alexander was a native of Aphrodisias in Caria (present-day Turkey)A. Chaniotis, 'Epigraphic evidence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Refractive Index
In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or refracted, when entering a material. This is described by Snell's law of refraction, , where ''θ''1 and ''θ''2 are the angle of incidence and angle of refraction, respectively, of a ray crossing the interface between two media with refractive indices ''n''1 and ''n''2. The refractive indices also determine the amount of light that is reflected when reaching the interface, as well as the critical angle for total internal reflection, their intensity (Fresnel's equations) and Brewster's angle. The refractive index can be seen as the factor by which the speed and the wavelength of the radiation are reduced with respect to their vacuum values: the speed of light in a medium is , and similarly the wavelength in that medium is , where ''� ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water
Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent). It is vital for all known forms of life, despite not providing food, energy or organic micronutrients. Its chemical formula, H2O, indicates that each of its molecules contains one oxygen and two hydrogen atoms, connected by covalent bonds. The hydrogen atoms are attached to the oxygen atom at an angle of 104.45°. "Water" is also the name of the liquid state of H2O at standard temperature and pressure. A number of natural states of water exist. It forms precipitation in the form of rain and aerosols in the form of fog. Clouds consist of suspended droplets of water and ice, its solid state. When finely divided, crystalline ice may precipitate in the form of snow. The gaseous state of water is steam or water vapor. W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minimum Deviation
In a prism, the angle of deviation () decreases with increase in the angle of incidence () up to a particular angle. This angle of incidence where the angle of deviation in a prism is minimum is called the minimum deviation position of the prism and that very deviation angle is known as the minimum angle of deviation (denoted by , , or ). The angle of minimum deviation is related with the refractive index as: n_ = \dfrac This is useful to calculate the refractive index of a material. Rainbow and halo occur at minimum deviation. Also, a thin prism is always set at minimum deviation. Formula In minimum deviation, the refracted ray in the prism is parallel to its base. In other words, the light ray is symmetrical about the axis of symmetry of the prism. Also, the angles of refractions are equal i.e. . And, the angle of incidence and angle of emergence equal each other (). This is clearly visible in the graph below. The formula for minimum deviation can be derived by ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atmospheric Optical Phenomena
Atmospheric optics is "the study of the optical characteristics of the atmosphere or products of atmospheric processes .... ncludingtemporal and spatial resolutions beyond those discernible with the naked eye". Meteorological optics is "that part of atmospheric optics concerned with the study of patterns observable with the naked eye". Nevertheless, the two terms are sometimes used interchangeably. Meteorological optical phenomena, as described in this article, are concerned with how the optical properties of Earth's atmosphere cause a wide range of optical phenomena and visual perception phenomena. Examples of meteorological phenomena include: *The blue color of the sky. This is from Rayleigh scattering, which redirects higher frequency/shorter wavelength (blue) sunlight back into the field of view of the observer. *The reddish color of the Sun when it is observed through a thick atmosphere, as during a sunrise or sunset. This is because red light is scattered less than blue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alexanders Dunkles Band
''Smyrnium olusatrum'', common name alexanders (or alisander) is an edible flowering plant of the family Apiaceae (Umbelliferae), which grows on waste ground and in hedges around the Mediterranean and Atlantic coastal regions of Europe. It was formerly widely grown as a pot herb, but is now appreciated mostly by foragers. Description Alexanders is a stout, glabrous (hairless) biennial growing to 150 (sometimes 180) cm tall, with a solid stem up to 22 mm in diameter, which becomes hollow and grooved with age. It has a tuberous tap-root which can be 60 cm long, as well as fibrous lateral roots. The stem leaves are arranged in a spiral (although the upper cauline ones are often opposite and sometimes in whorls of 3), with an inflated, purple-striped, fleshy petiole that has papery margins towards the base. The compound leaves are broadly diamond-shaped, 2- or 3-times ternately (sometimes pinnately) divided. Sometimes they are slightly hairy towards the base. The individual leaf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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