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Blue Sun
The Sun may appear blue after volcanic eruptions or major forest fires. This is typically due to scattering by aerosol An aerosol is a suspension (chemistry), suspension of fine solid particles or liquid Drop (liquid), droplets in air or another gas. Aerosols can be generated from natural or Human impact on the environment, human causes. The term ''aerosol'' co ... particles. Normal Rayleigh scattering is caused by particles much smaller than the wavelength of visible light. The scattering which causes the blue sun appearance is due to larger particles whose size is similar to the wavelength of light. See also * Blue moon – a similar phenomenon affecting the Moon * Green flash – a phenomenon at sunset, when the last edge of the sun may flash green or even blue References Atmospheric optical phenomena Solar phenomena {{geophysics-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scattering
In physics, scattering is a wide range of physical processes where moving particles or radiation of some form, such as light or sound, are forced to deviate from a straight trajectory by localized non-uniformities (including particles and radiation) in the medium through which they pass. In conventional use, this also includes deviation of reflected radiation from the angle predicted by the law of reflection. Reflections of radiation that undergo scattering are often called ''diffuse reflections'' and unscattered reflections are called ''specular'' (mirror-like) reflections. Originally, the term was confined to light scattering (going back at least as far as Isaac Newton in the 17th century). As more "ray"-like phenomena were discovered, the idea of scattering was extended to them, so that William Herschel could refer to the scattering of "heat rays" (not then recognized as electromagnetic in nature) in 1800. John Tyndall, a pioneer in light scattering research, noted the connecti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerosol
An aerosol is a suspension (chemistry), suspension of fine solid particles or liquid Drop (liquid), droplets in air or another gas. Aerosols can be generated from natural or Human impact on the environment, human causes. The term ''aerosol'' commonly refers to the mixture of particulates in air, and not to the particulate matter alone. Examples of natural aerosols are fog, mist or dust. Examples of human caused aerosols include particulate air pollutants, mist from the discharge at hydroelectric dams, irrigation mist, perfume from Spray nozzle, atomizers, smoke, dust, Pesticide, sprayed pesticides, and medical treatments for respiratory illnesses. Several types of atmospheric aerosol have a significant effect on Earth's climate: volcanic, desert dust, sea-salt, that originating from biogenic sources and human-made. Volcanic aerosol forms in the stratosphere after an eruption as droplets of sulfuric acid that can prevail for up to two years, and reflect sunlight, lowering tempera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rayleigh Scattering
Rayleigh scattering ( ) is the scattering or deflection of light, or other electromagnetic radiation, by particles with a size much smaller than the wavelength of the radiation. For light frequencies well below the resonance frequency of the scattering medium (normal dispersion relation, dispersion regime), the amount of scattering is inversely proportional to the fourth power of the wavelength (e.g., a blue color is scattered much more than a red color as light propagates through air). The phenomenon is named after the 19th-century British physicist Lord Rayleigh (John William Strutt). Rayleigh scattering results from the electric polarizability of the particles. The oscillating electric field of a light wave acts on the charges within a particle, causing them to move at the same frequency. The particle, therefore, becomes a small radiating dipole whose radiation we see as scattered light. The particles may be individual atoms or molecules; it can occur when light travels throu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blue Moon
A blue moon refers either to the presence of a second full moon in a calendar month, to the third full moon in a season containing four, or to a moon that appears blue due to atmospheric effects. The calendrical meaning of "blue moon" is unconnected to the other meanings. It is often referred to as “traditional”, but since no occurrences are known prior to 1937 it is better described as an invented tradition or “modern American folklore”. The practice of designating the second full moon in a month as "blue" originated with amateur astronomer James Hugh Pruett in 1946. It does not come from Native American lunar tradition, as is sometimes supposed. The moon – not necessarily full – can sometimes appear blue due to atmospheric emissions from large forest fires or volcanoes, though the phenomenon is rare and unpredictable (hence the saying “once in a blue moon”). A calendrical blue moon (by Pruett's definition) is predictable and relatively common, happening 7 t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Green Flash
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 limb; the green appearance usually lasts for no more than two seconds. Rarely, the green flash can resemble a green ray shooting up from the sunset or sunrise point. Green flashes occur because the Earth's atmosphere can cause the light from the Sun to separate, via wavelength varying refraction, into different colors. Green flashes are a group of similar phenomena that stem from slightly different causes, and therefore, some types of green flashes are more common than others. Observing Green flashes may be observed from any altitude. They usually are seen at an unobstructed horizon, such as over the ocean, but are possible over cloud tops and mountain tops as well. They may occur at any latitude, although at the equator, the flash rarely l ... [...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] |
