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Single Cell Thunderstorm
A pulse storm is a single cell thunderstorm of substantial intensity which only produces severe weather for short periods of time. Such a storm weakens and then generates another short burst – hence "pulse". The term was coined by researchers at the National Severe Storms Laboratory in 1979 to describe a single storm cell briefly becoming severe within a cluster of multi-cellular thunderstorms, but has since been used to describe a variety of isolated and brief thunderstorms with both severe and non-severe characteristics. __TOC__ Description Single cell thunderstorms ordinarily form in environments with low wind shear and moderate instability, with the low wind shear contributing to a short average lifespan of less than an hour. When the instability, calculated by convective available potential energy (CAPE), is strong, the updraft will bring a larger amount of humid air very high above ground and generate a cumulonimbus cloud with high water and ice content. When the rain conte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Storm Cell
A storm cell is an air mass that contains up and down vertical draft, drafts in convective loops and that moves and reacts as a single entity, functioning as the smallest unit of a storm-producing system. An organized grouping of thunder clouds will thus be considered as a series of storm cells with their up/downdrafts being independent or interfering one with the other. Characteristics A storm cell can extend over an area the size of a few tens of square miles/kilometers and last 30 minutes or so. When the updraft and the environmental wind shear is well coordinated, the size and the duration of the cell can be much greater leading to a supercell. Finally, storm cells can form on the Outflow (meteorology), outflow of previous cells leading to multicellular thunderstorms or mesoscale convective systems. Slow motion of these more intense storm cells or groups of cells can produce large precipitation accumulations and flash flood, or other dangerous phenomena like hail and tornadoes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tornado
A tornado is a violently rotating column of air that is in contact with the surface of Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, although the word cyclone is used in meteorology to name a weather system with a low-pressure area in the center around which, from an observer looking down toward the surface of the Earth, winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. Tornadoes come in many shapes and sizes, and they are often (but not always) visible in the form of a funnel cloud, condensation funnel originating from the base of a cumulonimbus cloud, with a cloud of rotating debris and dust beneath it. Most tornadoes have wind speeds less than , are about across, and travel several kilometers (a few miles) before dissipating. The Tornado records#Highest winds observed in a tornado, most extreme tornadoes can attain wind speeds of mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Project NIMROD
Project NIMROD (Northern Illinois Meteorological Research On Downburst) was a meteorological field study of severe thunderstorms and their damaging winds conducted by the National Center for Atmospheric Research (NCAR). It took place in the Greater Chicago area from May 15 to June 30, 1978. Data collected was from Pulse storm, single cell thunderstorms as well as mesoscale convective systems, such as bow echoes. Using Weather radar#Velocity, Doppler weather radars and damage clues on the ground, the team studied mesocyclones, downbursts and Outflow boundary, gust fronts. NIMROD was the first time that microbursts, very localized strong downdrafts under thunderstorms, were detected; this helped improve airport and public safety by the development of systems like the Terminal Doppler Weather Radar and the Low-level windshear alert system. Description The project was set up by Ted Fujita and Ramesh Srivastava from the University of Chicago, with research assistants from the universit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Outflow (meteorology)
Outflow, in meteorology, is air that flows outwards from a storm system. It is associated with ridging, or anticyclone, anticyclonic flow. In the low levels of the troposphere, outflow radiates from thunderstorms in the form of a wedge of rain-cooled air, which is visible as a thin rope-like cloud on weather satellite imagery or a fine line on weather radar imagery. For observers on the ground, a thunderstorm outflow boundary often approaches in otherwise clear skies as a low, thick cloud that brings with it a gust front. Low-level outflow boundaries can disrupt the center of small tropical cyclones. However, outflow aloft is essential for the strengthening of a tropical cyclone. If this outflow is restricted or undercut, the tropical cyclone weakens. If two tropical cyclones are close, the upper-level outflow from the upwind system can limit the development of the other system. Thunderstorms For thunderstorms, outflow tends to indicate the development of a system. Large quan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Outflow Boundary
An outflow boundary, also known as a gust front, is a storm-scale or mesoscale meteorology, mesoscale boundary separating thunderstorm-cooled air (Outflow (meteorology), outflow) from the surrounding air; similar in effect to a cold front, with passage marked by a wind shift and usually a drop in temperature and a related pressure jump. Outflow boundaries can persist for 24 hours or more after the thunderstorms that generated them dissipate, and can travel hundreds of kilometers from their area of origin. New thunderstorms often develop along outflow boundaries, especially near the point of intersection with another boundary (cold front, dry line, another outflow boundary, etc.). Outflow boundaries can be seen either as fine lines on weather radar imagery or else as arcs of low clouds on weather satellite imagery. From the ground, outflow boundaries can be co-located with the appearance of roll clouds and shelf clouds. Outflow boundaries create low-level wind shear which can be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shower (precipitation)
A shower is a mode of precipitation characterized by an abrupt start and end, and by rapid variations in intensity. Often strong and short-lived, it comes from Atmospheric convection, convective clouds, like Cumulus congestus cloud, cumulus congestus. A shower will produce rain if the temperature is above the freezing point in the cloud, or snow / ice pellets / snow pellets / hail if the temperature is below it at some point. In a meteorological observation, such as the METAR, they are noted SH giving respectively SHRA, SHSN, SHPL, SHGS and SHGR. Formation Convection occurs when the Earth's surface, especially within a conditionally unstable or moist atmosphere, becomes heated more than its surroundings and in turn leads to significant evaporation. The raised air parcel in a colder environment at altitude will cool, according to the adiabatic thermal gradient, forming clouds, and later precipitation above the lifted condensation level (LCL). Depending on the convective available ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thunder
Thunder is the sound caused by lightning. Depending upon the distance from and nature of the lightning, it can range from a long, low rumble to a sudden, loud crack. The sudden increase in temperature and hence pressure caused by the lightning produces rapid Thermal expansion, expansion of the air in the path of a Lightning strike, lightning bolt. In turn, this expansion of air creates a Shock wave, sonic shock wave, often referred to as a "thunderclap" or "peal of thunder". The scientific study of thunder is known as ''brontology'' and the irrational fear (phobia) of thunder is called ''brontophobia''. Etymology The ''d'' in Modern English ''thunder'' (from earlier Old English ''þunor'') is epenthetic, and is now found as well in Modern Dutch ''donder'' (cf. Middle Dutch ''donre''; also Old Norse ''þorr'', Old Frisian ''þuner'', Old High German ''donar'', all ultimately descended from Proto-Germanic *''þunraz''). In Latin the term was ''tonare'' "to thunder". The name of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lightning
Lightning is a natural phenomenon consisting of electrostatic discharges occurring through the atmosphere between two electrically charged regions. One or both regions are within the atmosphere, with the second region sometimes occurring on the land, ground. Following the lightning, the regions become partially or wholly electrically neutralized. Lightning involves a near-instantaneous release of energy on a scale averaging between 200 megajoules and 7 gigajoules. The air around the lightning flash rapidly heats to temperatures of about . There is an emission of electromagnetic radiation across a wide range of wavelengths, some visible as a bright flash. Lightning also causes thunder, a sound from the shock wave which develops as heated gases in the vicinity of the discharge experience a sudden increase in pressure. The most common occurrence of a lightning event is known as a thunderstorm, though they can also commonly occur in other types of energetic weather systems, such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cumulonimbus
Cumulonimbus () is a dense, towering, vertical cloud, typically forming from water vapor condensing in the lower troposphere that builds upward carried by powerful buoyant air currents. Above the lower portions of the cumulonimbus the water vapor becomes ice crystals, such as snow and graupel, the interaction of which can lead to hail and to lightning formation, respectively. When causing thunderstorms, these clouds may be called thunderheads. Cumulonimbus can form alone, in clusters, or along squall lines. These clouds are capable of producing lightning and other dangerous severe weather, such as tornadoes, hazardous winds, and large hailstones. Cumulonimbus progress from overdeveloped cumulus congestus clouds and may further develop as part of a supercell. Cumulonimbus is abbreviated as Cb. Description Towering cumulonimbus clouds are typically accompanied by smaller cumulus clouds. The cumulonimbus base may extend several kilometres (miles) across, or be as small as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cumulus Congestus
Cumulus congestus or towering cumulus clouds are a species of cumulus that can be based in the low- to middle-height ranges. They achieve considerable vertical development in areas of deep, moist convection. They are an intermediate stage between cumulus mediocris and cumulonimbus, sometimes producing rainshowers, snow, or ice pellets. Precipitation that evaporates before reaching the surface is virga. Description Cumulus congestus clouds are characteristic of unstable regions of atmosphere that are undergoing convection. They are often characterized by sharp outlines and great vertical development. Since strong updrafts produce (and primarily compose) them, the clouds are typically taller than they are wide; cloud tops can reach , or higher in the tropics. Cumulus congestus clouds are formed by the development of cumulus mediocris generally, though they can also be formed from altocumulus castellanus or stratocumulus castellanus, which are forms of cumulus castellanus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orage Ordinaire (1873–1934), British intellectual and editor of ''The New Age''
{{disambiguation, surname ...
Orage may refer to: * ''Orage'' (film), a 1938 French-language film * ''Orage'' (Liszt), a piano piece by Franz Liszt * French destroyer ''Orage'', a French naval destroyer that was sunk in the battle of Boulogne (1940) * French landing platform dock Orage (L9022), a French naval landing ship ( Ouragan-class landing platform dock) that served from 1968 to 2007 * Orage, a calendar application in the desktop environment Xfce People with the surname * Alfred Richard Orage Alfred Richard Orage (22 January 1873 – 6 November 1934) was a British influential figure in socialist politics and modernist culture, now best known for editing the magazine '' The New Age'' before the First World War. While he was working ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Downburst
In meteorology, a downburst is a strong downward and outward gushing wind system that emanates from a point source above and blows radially, that is, in straight lines in all directions from the area of impact at surface level. It originates under deep, moist convective conditions like cumulus congestus or cumulonimbus. Capable of producing damaging winds, it may sometimes be confused with a tornado, where high-velocity winds circle a central area, and air moves inward and upward. These usually last for seconds to minutes. Downbursts are particularly strong downdrafts within thunderstorms (or deep, moist convection as sometimes downbursts emanate from cumulonimbus or even cumulus congestus clouds that are not producing lightning). Downbursts are most often created by an area of significantly precipitation-cooled air that, after reaching the surface ( subsiding), spreads out in all directions producing strong winds. Dry downbursts are associated with thunderstorms that ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
