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Pileus (meteorology)
A pileus (; Latin for "cap"), also called scarf cloud or cap cloud, is a small, horizontal, lenticular cloud appearing above a cumulus or cumulonimbus cloud. Pileus clouds are often short-lived, with the main cloud beneath them rising through convection to absorb them. They are formed by strong updraft at lower altitudes, acting upon moist air above, causing the air to cool to its dew point. As such, they are usually indicators of severe weather, and a pileus found atop a cumulus cloud often foreshadows transformation into a cumulonimbus cloud, as it indicates a strong updraft within the cloud. Pilei can also form above mountains, ash clouds, and pyrocumulus clouds from erupting volcanoes. Pilei form above some mushroom clouds of high- yield nuclear detonations. Appearance Sometimes several pileus clouds are observed above each other. The bright iridescent colors seen in pileus are sunlight diffracted in water vapor. Iridescent colors are strongest when the diffracting drop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cumulus Pileus
A pileus (; Latin for "cap"), also called scarf cloud or cap cloud, is a small, horizontal, lenticular cloud appearing above a cumulus or cumulonimbus cloud. Pileus clouds are often short-lived, with the main cloud beneath them rising through convection to absorb them. They are formed by strong updraft at lower altitudes, acting upon moist air above, causing the air to cool to its dew point. As such, they are usually indicators of severe weather, and a pileus found atop a cumulus cloud often foreshadows transformation into a cumulonimbus cloud, as it indicates a strong updraft within the cloud. Pilei can also form above mountains, ash clouds, and pyrocumulus clouds from erupting volcanoes. Pilei form above some mushroom clouds of high- yield nuclear detonations. Appearance Sometimes several pileus clouds are observed above each other. The bright iridescent colors seen in pileus are sunlight diffracted in water vapor. Iridescent colors are strongest when the diffracting drop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Eruption
Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed. Some volcanoes may exhibit only one characteristic type of eruption during a period of activity, while others may display an entire sequence of types all in one eruptive series. There are three different types of eruptions: * Magmatic eruptions are the most well-observed type of eruption. They involve the decompression of gas within magma that propels it forward. * Phreatic eruptions are driven by the superheating of steam due to the close proximity of magma. This type exhibits no magmatic release, instead causing the granulation of existing rock. * Phreatomagmatic eruptions are driven by the direct interaction of magma and water, as opposed to phreatic erup ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lenticular Cloud
Lenticular clouds (Latin: ''Lenticularis'' lentil-shaped, from ''lenticula'' lentil) are stationary clouds that form mostly in the troposphere, typically in parallel alignment to the wind direction. They are often comparable in appearance to a lens or saucer. Nacreous clouds that form in the lower stratosphere sometimes have lenticular shapes. There are three main types of lenticular clouds: altocumulus standing lenticular (ACSL), stratocumulus standing lenticular (SCSL), and cirrocumulus standing lenticular (CCSL), varying in altitude above the ground. Because of their unique appearance, they have been suggested as an explanation for some unidentified flying object (UFO) sightings. Formation and appearance As air travels along the surface of the Earth, obstructions are often encountered, including natural features, such as mountains or hills, and artificial structures, such as buildings and other constructions, which disrupt the flow of air into "eddies", or areas of turb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atmospheric Convection
Atmospheric convection is the result of a parcel-environment instability, or temperature difference layer in the atmosphere. Different lapse rates within dry and moist air masses lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to increased winds, cumulus cloud development, and decreased surface dew points. Moist convection leads to thunderstorm development, which is often responsible for severe weather throughout the world. Special threats from thunderstorms include hail, downbursts, and tornadoes. Overview There are a few general archetypes of atmospheric instability that are used to explain convection (or lack thereof). A necessary (but not sufficient) condition for convection is that the environmental lapse rate (the rate of decrease of temperature with height) is steeper than the lapse rate experienced by a rising parcel of air. When this condition is met, upward-displaced air parcels can become buoyant and th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cumulonimbus Incus
A cumulonimbus incus (Latin ''incus'', "anvil"), also known as an anvil cloud, is a cumulonimbus cloud which has reached the level of stratospheric stability and has formed the characteristic flat, anvil-top shape. It signifies the thunderstorm in its mature stage, succeeding the cumulonimbus calvus stage. Cumulonimbus incus is a sub-form of Cumulonimbus capillatus. Hazards A cumulonimbus incus is a mature thunderstorm cloud generating many dangerous elements. * Lightning: this storm cloud is capable of producing bursts of cloud-to-ground lightning. * Hail: hailstones may fall from this cloud if it's a highly unstable environment (which favours a more vigorous storm updraft). * Heavy rain: this cloud may drop several inches (millimetres) of rain in a short amount of time. This can cause flash flooding. * Strong wind: gale-force winds from a downburst may occur under this cloud. * Tornadoes: in severe cases (most commonly with supercells), it can produce tornadoes. Classi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Meteorological Society
The American Meteorological Society (AMS) is the premier scientific and professional organization in the United States promoting and disseminating information about the Atmospheric sciences, atmospheric, Oceanography, oceanic, and Hydrology, hydrologic sciences. Its mission is to advance the atmospheric and related sciences, technologies, applications, and services for the benefit of society. Background Founded on December 29, 1919, by Charles Franklin Brooks at a meeting of the American Association for the Advancement of Science in St. Louis and incorporated on January 21, 1920, the American Meteorological Society has a membership of more than 13,000 weather, water, and climate scientists, professionals, researchers, educators, students, and enthusiasts. AMS offers numerous programs and services in the sphere of water, weather and climate sciences. It publishes eleven atmospheric and related oceanic and hydrologic journals (in print and online), sponsors as many as twelve conf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cumulonimbus Velum
Cumulonimbus velum (Cb vel) (from the Latin ''cumulonimbus'', "column-rain" + ''velum'', "veil") is a cumulonimbus cloud with an accessory cloud An accessory cloud is a cloud which is dependent on a larger cloud system for its development and continuance. It is often an appendage but also can be adjacent to the parent cloud system. The arcus and roll clouds, shelf cloud, wall cloud, and ... veil wrapped around its mid area, representing an area of humid stable air created as a result of the growth of the parent cumulonimbus. The altostratus velum cloud appears dark in comparison to its parent cloud, and can persist even after the cumulonimbus has disintegrated. The velum is very rare, as conditions necessary in development are infrequent. References Cumulus {{Cloud-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Altostratus
Altostratus is a middle-altitude cloud genus made up of water droplets, ice crystals, or a mixture of the two. Altostratus clouds are formed when large masses of warm, moist air rise, causing water vapor to condense. Altostratus clouds are usually gray or blueish featureless sheets, although some variants have wavy or banded bases. The sun can be seen through thinner altostratus clouds, but thicker layers can be quite opaque. Altostratus clouds usually predict the arrival of warm fronts. Once altostratus clouds associated with a warm front arrive, continuous rain or snow will usually follow in the next 12 to 24 hours. Although altostratus clouds predict the arrival of warmer, wetter weather, they themselves do not produce significant precipitation. Thunderstorms can be embedded in altostratus clouds; however, bringing showers. Because altostratus clouds can contain ice crystals, they can produce some optical phenomena like iridescence and coronas. Description Altostratus c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Detonation
A nuclear explosion is an explosion that occurs as a result of the rapid release of energy from a high-speed nuclear reaction. The driving reaction may be nuclear fission or nuclear fusion or a multi-stage cascading combination of the two, though to date all fusion-based weapons have used a fission device to initiate fusion, and a pure fusion weapon remains a hypothetical device. Nuclear explosions are used in nuclear weapons and nuclear testing. Atmospheric nuclear explosions are associated with mushroom clouds, although mushroom clouds can occur with large chemical explosions. It is possible to have an air-burst nuclear explosion without those clouds. Nuclear explosions produce radiation and radioactive debris that is harmful to humans and can cause moderate to severe skin burns, eye damage, radiation sickness, radiation-induced cancer and possible death depending on how far from the blast radius a person is. Nuclear explosions can also have detrimental effects on the clima ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Weapon Yield
The explosive yield of a nuclear weapon is the amount of energy released when that particular nuclear weapon is detonated, usually expressed as a TNT equivalent (the standardized equivalent mass of trinitrotoluene which, if detonated, would produce the same energy discharge), either in kilotonnes (kt—thousands of tonnes of TNT), in megatonnes (Mt—millions of tonnes of TNT), or sometimes in terajoules (TJ). An explosive yield of one terajoule is equal to . Because the accuracy of any measurement of the energy released by TNT has always been problematic, the conventional definition is that one kilotonne of TNT is held simply to be equivalent to 1012 calories. The yield-to-weight ratio is the amount of weapon yield compared to the mass of the weapon. The practical maximum yield-to-weight ratio for fusion weapons (thermonuclear weapons) has been estimated to six megatonnes of TNT per tonne of bomb mass (25 TJ/kg). Yields of 5.2 megatonnes/tonne and higher have been reported ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mushroom Cloud
A mushroom cloud is a distinctive mushroom-shaped flammagenitus cloud of debris, smoke and usually condensed water vapor resulting from a large explosion. The effect is most commonly associated with a nuclear explosion, but any sufficiently energetic detonation or deflagration will produce the same effect. They can be caused by powerful conventional weapons, like thermobaric weapons, including the ATBIP and GBU-43/B Massive Ordnance Air Blast. Some volcanic eruptions and impact events can produce natural mushroom clouds. Mushroom clouds result from the sudden formation of a large volume of lower-density gases at any altitude, causing a Rayleigh–Taylor instability. The buoyant mass of gas rises rapidly, resulting in turbulent vortices curling downward around its edges, forming a temporary vortex ring that draws up a central column, possibly with smoke, debris, condensed water vapor, or a combination of these, to form the "mushroom stem". The mass of gas plus entrained moist ai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcano
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are diverging or converging, and most are found underwater. For example, a mid-ocean ridge, such as the Mid-Atlantic Ridge, has volcanoes caused by divergent tectonic plates whereas the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes can also form where there is stretching and thinning of the crust's plates, such as in the East African Rift and the Wells Gray-Clearwater volcanic field and Rio Grande rift in North America. Volcanism away from plate boundaries has been postulated to arise from upwelling diapirs from the core–mantle boundary, deep in the Earth. This results in hotspot volcanism, of which the Hawaiian hotspot is an example. Volcanoes are usually not created where two tectonic plates slide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
