|
Tornadogenesis
Tornadogenesis is the process by which a tornado forms. There are many types of tornadoes and these vary in methods of formation. Despite ongoing scientific study and high-profile research projects such as VORTEX, tornadogenesis is a volatile process and the intricacies of many of the mechanisms of tornado formation are still poorly understood. A tornado is a violently rotating column of air in contact with the surface and a cumuliform cloud base. Tornado formation is caused by the stretching and aggregating/merging of environmental and/or storm-induced vorticity that tightens it into an intense vortex. There are various ways this may come about and thus various forms and sub-forms of tornadoes. Although each tornado is unique, most kinds of tornadoes go through a life cycle of formation, maturation, and dissipation. The process by which a tornado dissipates or decays, occasionally conjured as tornadolysis, is of particular interest for study as is tornadogenesis, longevity, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rear Flank Downdraft
The rear flank downdraft (RFD) is a region of dry air wrapping around the back of a mesocyclone in a supercell thunderstorm. These areas of descending air are thought to be essential in the production of many supercellular tornadoes. Large hail within the rear flank downdraft often shows up brightly as a hook on weather radar images, producing the characteristic ''hook echo'', which often indicates the presence of a tornado. Formation The rear flank downdraft can arise owing to negative buoyancy, which can be generated by cold anomalies produced at the rear of the supercell thunderstorm by evaporative cooling of precipitation or hail melting, or injection of dry and cooler air in the cloud, and by vertical perturbation pressure gradients that can arise from vertical gradients of vertical vorticity, ''stagnation'' of environmental flow at an updraft, and pressure perturbations due to vertical buoyancy variations (which are partially due to hydrostatic effects). Vertical press ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tornado
A tornado is a violently rotating column of air that is in contact with both the surface of the 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. Tornadoes come in many shapes and sizes, and they are often visible in the form of a 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 most extreme tornadoes can attain wind speeds of more than , are more than in diameter, and stay on the ground for more than 100 k ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tornado Touching Down In Falcon, Colorado
A tornado is a violently rotating column of air that is in contact with both the surface of the 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. Tornadoes come in many shapes and sizes, and they are often visible in the form of a 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 most extreme tornadoes can attain wind speeds of more than , are more than in diameter, and stay on the ground for more than 100 k ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convective Storm Detection
Convective storm detection is the meteorological observation, and short-term prediction, of deep moist convection (DMC). DMC describes atmospheric conditions producing single or clusters of large vertical extension clouds ranging from cumulus congestus to cumulonimbus, the latter producing thunderstorms associated with lightning and thunder. Those two types of clouds can produce severe weather at the surface and aloft. The ability to discern the presence of deep moist convection in a storm significantly improves meteorologists' capacity to predict and monitor associated phenomena such as tornadoes, large hail, strong winds, and heavy rain leading to flash flooding. It relies on direct eyewitness observations, for example from storm spotters; and on remote sensing, especially weather radar. Some in situ measurements are used for direct detection as well, notably, wind speed reports from surface observation stations. It is part of the ''integrated warning system'', consisting of p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tornadogenesis
Tornadogenesis is the process by which a tornado forms. There are many types of tornadoes and these vary in methods of formation. Despite ongoing scientific study and high-profile research projects such as VORTEX, tornadogenesis is a volatile process and the intricacies of many of the mechanisms of tornado formation are still poorly understood. A tornado is a violently rotating column of air in contact with the surface and a cumuliform cloud base. Tornado formation is caused by the stretching and aggregating/merging of environmental and/or storm-induced vorticity that tightens it into an intense vortex. There are various ways this may come about and thus various forms and sub-forms of tornadoes. Although each tornado is unique, most kinds of tornadoes go through a life cycle of formation, maturation, and dissipation. The process by which a tornado dissipates or decays, occasionally conjured as tornadolysis, is of particular interest for study as is tornadogenesis, longevity, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supercell
A supercell is a thunderstorm characterized by the presence of a mesocyclone: a deep, persistently rotating updraft. Due to this, these storms are sometimes referred to as rotating thunderstorms. Of the four classifications of thunderstorms (supercell, squall line, multi-cell, and single-cell), supercells are the overall least common and have the potential to be the most severe. Supercells are often isolated from other thunderstorms, and can dominate the local weather up to away. They tend to last 2–4 hours. Supercells are often put into three classification types: classic (Normal precipitation level), low-precipitation (LP), and high-precipitation (HP). LP supercells are usually found in climates that are more arid, such as the high plains of the United States, and HP supercells are most often found in moist climates. Supercells can occur anywhere in the world under the right pre-existing weather conditions, but they are most common in the Great Plains of the United State ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesocyclone
A mesocyclone is a meso-gamma mesoscale (or storm scale) region of rotation (vortex), typically around in diameter, most often noticed on radar within thunderstorms. In the northern hemisphere it is usually located in the right rear flank (back edge with respect to direction of movement) of a supercell, or often on the eastern, or leading, flank of a high-precipitation variety of supercell. The area overlaid by a mesocyclone’s circulation may be several miles (km) wide, but substantially larger than any tornado that may develop within it, and it is within mesocyclones that intense tornadoes form. Description Mesocyclones are medium-scale vortices of rising and converging air that circulate around a vertical axis. They are most often associated with a local region of low-pressure. Their rotation is (usually) in the same direction as low pressure systems in a given hemisphere: counter-clockwise in the northern, and clockwise in the southern hemisphere, with the only occasio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrocumulonimbus
The cumulonimbus flammagenitus cloud (CbFg), also known as the pyrocumulonimbus cloud, is a type of cumulonimbus cloud that forms above a source of heat, such as a wildfire or volcanic eruption, and may sometimes even extinguish the fire that formed it. It is the most extreme manifestation of a flammagenitus cloud. According to the American Meteorological Society’s Glossary of Meteorology, a flammagenitus is "a cumulus cloud formed by a rising thermal from a fire, or enhanced by buoyant plume emissions from an industrial combustion process." Analogous to the meteorological distinction between cumulus and cumulonimbus, the CbFg is a fire-aided or –caused convective cloud, like a flammagenitus, but with considerable vertical development. The CbFg reaches the upper troposphere or even lower stratosphere and may involve precipitation (although usually light), hail, lightning, extreme low-level winds, and in some cases even tornadoes. The combined effects of these phenome ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VORTEX Projects
The Verification of the Origins of Rotation in Tornadoes Experiment (or VORTEX) are field experiments that study tornadoes. VORTEX1 was the first time scientists completely researched the entire evolution of a tornado with an array of instrumentation, enabling a greater understanding of the processes involved with tornadogenesis. A violent tornado near Union City, Oklahoma was documented in its entirety by chasers of the Tornado Intercept Project (TIP) in 1973. Their visual observations led to advancement in understanding of tornado structure and life cycles. VORTEX2 used enhanced technology that allowed scientists to improve forecasting capabilities and improve lead time on advanced warnings to residents. VORTEX2 sought to reveal how tornadoes form, how long they last and why they last that long, and what causes them to dissipate. VORTEX1 and VORTEX2 was based on the use of large fleets of instrumented vehicles that ran on land, as well as aircraft and mobile radars. Important wo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake-effect Snow
Lake-effect snow is produced during cooler atmospheric conditions when a cold air mass moves across long expanses of warmer lake water. The lower layer of air, heated up by the lake water, picks up water vapor from the lake and rises up through the colder air above. The vapor then freezes and is deposited on the leeward (downwind) shores. The same effect also occurs over bodies of saline water, when it is termed ocean-effect or bay-effect snow. The effect is enhanced when the moving air mass is uplifted by the orographic influence of higher elevations on the downwind shores. This uplifting can produce narrow but very intense bands of precipitation, which deposit at a rate of many inches of snow each hour, often resulting in a large amount of total snowfall. The areas affected by lake-effect snow are called snowbelts. These include areas east of the Great Lakes in North America, the west coasts of northern Japan, the Kamchatka Peninsula in Russia, and areas near the Great S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VORTEX
In fluid dynamics, a vortex ( : vortices or vortexes) is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved. Vortices form in stirred fluids, and may be observed in smoke rings, whirlpools in the wake of a boat, and the winds surrounding a tropical cyclone, tornado or dust devil. Vortices are a major component of turbulent flow. The distribution of velocity, vorticity (the curl of the flow velocity), as well as the concept of circulation are used to characterise vortices. In most vortices, the fluid flow velocity is greatest next to its axis and decreases in inverse proportion to the distance from the axis. In the absence of external forces, viscous friction within the fluid tends to organise the flow into a collection of irrotational vortices, possibly superimposed to larger-scale flows, including larger-scale vortices. Once formed, vortices can move, stretch, twist, and interact in complex ways. A moving vortex carries s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Middle Latitudes
The middle latitudes (also called the mid-latitudes, sometimes midlatitudes, or moderate latitudes) are a spatial region on Earth located between the Tropic of Cancer (latitudes 23°26'22") to the Arctic Circle (66°33'39"), and Tropic of Capricorn (-23°26'22") to the Antarctic Circle (-66°33'39"). They include Earth's subtropical and temperate zones, which lie between the two tropics and the polar circles. Weather fronts and extratropical cyclones are usually found in this area, as well as occasional tropical cyclones or subtropical cyclones, which have traveled from their areas of formation closer to the Equator. The prevailing winds in the middle latitudes are often very strong. These parts of the world also see a wide variety of fast-changing weather as cold air masses from the poles and warm air masses from the tropics constantly push up and down over them against each other, sometimes alternating within hours of each other, especially in the roaring forties (latitudes betw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
