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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 occasi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesocyclone Detection Algorithm
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 occasi ... [...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&nb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supercell Side View
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] |
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 Stat ... [...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 Stat ... [...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, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hook Echo
A hook echo is a pendant or hook-shaped weather radar signature as part of some supercell thunderstorms. It is found in the lower portions of a storm as air and precipitation flow into a mesocyclone, resulting in a curved feature of reflectivity. The echo is produced by rain, hail, or even debris being wrapped around the supercell. It is one of the classic hallmarks of tornado-producing supercells. The National Weather Service may consider the presence of a hook echo coinciding with a tornado vortex signature as sufficient to justify issuing a tornado warning. History Because of the unpredictable and potentially catastrophic nature of tornadoes, the possibility of detecting tornadoes via radar was discussed in the meteorological community in the earliest days of meteorological radar.Huff, F.A., H.W. Hiser, and S.G. Bigler, 1954Study of an Illinois tornado using radar, synoptic weather and field survey data Report of Investigation 22, Champaign, IL, pp. 73 The first associatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesoscale Convective Vortex
A mesovortex is a small-scale rotational feature found in a convective storm, such as a quasi-linear convective system (QLCS, i.e. squall line), a supercell, or the eyewall of a tropical cyclone. Mesovortices range in diameter from tens of miles to a mile or less and can be immensely intense. Eyewall mesovortex An ''eyewall mesovortex'' is a small-scale rotational feature found in an eyewall of an intense tropical cyclone. Eyewall mesovortices are similar, in principle, to small "suction vortices" often observed in multiple-vortex tornadoes. In these vortices, wind speed can be up to 10% higher than in the rest of the eyewall. Eyewall mesovortices are most common during periods of intensification in tropical cyclones. Eyewall mesovortices often exhibit unusual behavior in tropical cyclones. They usually revolve around the low pressure center, but sometimes they remain stationary. Eyewall mesovortices have even been documented to cross the eye of a storm. These phenomena have bee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wall Cloud
A wall cloud (murus or pedestal cloud) is a large, localized, persistent, and often abrupt lowering of cloud that develops beneath the surrounding base of a cumulonimbus cloud and from which tornadoes sometimes form. It is typically beneath the rain-free base (RFB) portion of a thunderstorm, and indicates the area of the strongest updraft within a storm. Rotating wall clouds are an indication of a mesocyclone in a thunderstorm; most strong tornadoes form from these. Many wall clouds do rotate; however, some do not. Genesis Wall clouds are formed by a process known as entrainment, when an inflow of warm, moist air rises and converges, overpowering wet, rain-cooled air from the normally downwind downdraft. As the warm air continues to entrain the cooler air, the air temperature drops and the dew point increases (thus the dew point depression decreases). As this air continues to rise, it becomes more saturated with moisture, which results in additional cloud condensation, so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesovortex
A mesovortex is a small-scale rotational feature found in a convective storm, such as a quasi-linear convective system (QLCS, i.e. squall line), a supercell, or the eyewall of a tropical cyclone. Mesovortices range in diameter from tens of miles to a mile or less and can be immensely intense. Eyewall mesovortex An ''eyewall mesovortex'' is a small-scale rotational feature found in an eyewall of an intense tropical cyclone. Eyewall mesovortices are similar, in principle, to small "suction vortices" often observed in multiple-vortex tornadoes. In these vortices, wind speed can be up to 10% higher than in the rest of the eyewall. Eyewall mesovortices are most common during periods of intensification in tropical cyclones. Eyewall mesovortices often exhibit unusual behavior in tropical cyclones. They usually revolve around the low pressure center, but sometimes they remain stationary. Eyewall mesovortices have even been documented to cross the eye of a storm. These phenomena have b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Low-pressure Area
In meteorology, a low-pressure area, low area or low is a region where the atmospheric pressure is lower than that of surrounding locations. Low-pressure areas are commonly associated with inclement weather (such as cloudy, windy, with possible rain or storms), while high-pressure areas are associated with lighter winds and clear skies. Winds circle anti-clockwise around lows in the northern hemisphere, and clockwise in the southern hemisphere, due to opposing Coriolis forces. Low-pressure systems form under areas of wind divergence that occur in the upper levels of the atmosphere (aloft). The formation process of a low-pressure area is known as cyclogenesis. In meteorology, atmospheric divergence aloft occurs in two kinds of places: * The first is in the area on the east side of upper troughs, which form half of a Rossby wave within the Westerlies (a trough with large wavelength that extends through the troposphere). * A second is an area where wind divergence aloft occu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weather Radar
Weather radar, also called weather surveillance radar (WSR) and Doppler weather radar, is a type of radar used to locate precipitation, calculate its motion, and estimate its type (rain, snow, hail etc.). Modern weather radars are mostly pulse-Doppler radars, capable of detecting the motion of rain droplets in addition to the intensity of the precipitation. Both types of data can be analyzed to determine the structure of storms and their potential to cause severe weather. During World War II, radar operators discovered that weather was causing echoes on their screen, masking potential enemy targets. Techniques were developed to filter them, but scientists began to study the phenomenon. Soon after the war, surplus radars were used to detect precipitation. Since then, weather radar has evolved on its own and is now used by national weather services, research departments in universities, and in television stations' weather departments. Raw images are routinely used and specialize ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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