|
Vertical Draft
In meteorology, an updraft (British English: ''up-draught'') is a small-scale current of rising air, often within a cloud. Overview Vertical drafts, known as updrafts or downdrafts, are localized regions of warm or cool air that move vertically. A mass of warm air will typically be less dense than the surrounding region, and so will rise until it reaches air that is either warmer or less dense than itself. The converse will occur for a mass of cool air, and is known as subsidence. This movement of large volumes of air, especially when regions of hot, wet air rise, can create large clouds, and is the central source of thunderstorms. Drafts can also be caused by low or high pressure regions. A low pressure region will attract air from the surrounding area, which will move towards the center and then rise, creating an updraft. A high pressure region will attract air from the surrounding area, which will move towards the center and sink, spawning a downdraft. Updrafts and downdraft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thunderstorm Updraft
A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are sometimes called thundershowers. Thunderstorms occur in cumulonimbus clouds. They are usually accompanied by strong winds and often produce heavy rain and sometimes snow, sleet, or hail, but some thunderstorms can produce little or no precipitation at all. Thunderstorms may line up in a series or become a rainband, known as a squall line. Strong or severe thunderstorms include some of the most dangerous weather phenomena, including large hail, strong winds, and tornadoes. Some of the most persistent severe thunderstorms, known as supercells, rotate as do cyclones. While most thunderstorms move with the mean wind flow through the layer of the troposphere that they occupy, vertical wind shear sometimes causes a deviation in their course at a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terminal Doppler Weather Radar
Terminal Doppler Weather Radar (TDWR) is a Doppler weather radar system with a three-dimensional "pencil beam" used primarily for the detection of hazardous wind shear conditions, precipitation, and winds aloft on and near major airports situated in climates with great exposure to thunderstorms in the United States. As of 2011, all were in-service with 45 operational radars, some covering multiple airports in major metropolitan locations, across the United States & Puerto Rico. Several similar weather radars have also been sold to other countries such as China (Hong Kong). Funded by the United States Federal Aviation Administration (FAA), TDWR technology was developed in the early 1990s at Lincoln Laboratory, part of the Massachusetts Institute of Technology, to assist air traffic controllers by providing real-time wind shear detection and high-resolution precipitation data. The primary advantage of TDWRs over previous weather radars is that it has a finer range resolution—me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aviation Meteorology
Meteorology is the scientific study of the Earth's atmosphere and short-term atmospheric phenomena (i.e. weather), with a focus on weather forecasting. It has applications in the military, aviation, energy production, transport, agriculture, construction, weather warnings and disaster management. Along with climatology, atmospheric physics and atmospheric chemistry, meteorology forms the broader field of the atmospheric sciences. The interactions between Earth's atmosphere and its oceans (notably El Niño and La Niña) are studied in the interdisciplinary field of hydrometeorology. Other interdisciplinary areas include biometeorology, space weather and planetary meteorology. Marine weather forecasting relates meteorology to maritime and coastal safety, based on atmospheric interactions with large bodies of water. Meteorologists study meteorological phenomena driven by solar radiation, Earth's rotation, ocean currents and other factors. These include everyday weathe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal
A thermal column (or thermal) is a rising mass of buoyant air, a convective current in the atmosphere, that transfers heat energy vertically. Thermals are created by the uneven heating of Earth's surface from solar radiation, and are an example of convection, specifically atmospheric convection. Thermals on Earth The Sun warms the ground, which in turn warms the air directly above. The warm air near the surface expands, becoming less dense than the surrounding air. The lighter air rises and cools due to its expansion in the lower pressure at higher altitudes. It stops rising when it has cooled to the same temperature, thus density, as the surrounding air. Associated with a thermal is a downward flow surrounding the thermal column. The downward-moving exterior is caused by colder air being displaced at the top of the thermal. The size and strength of thermals are influenced by the properties of the lower atmosphere (the ''troposphere''). When the air is cold, bubbles of wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forward Flank Downdraft
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] |
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 pres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New Zealand National Airways Corporation Flight 441
New Zealand National Airways Corporation Flight 441 (NZ441) was a scheduled flight of the National Airways Corporation (New Zealand), New Zealand National Airways Corporation from Whenuapai, Auckland to Tauranga. On 3 July 1963 at approximately 9:09 am NZST, the flight, a Douglas DC-3, Douglas DC-3 Skyliner, flew into a vertical rock face in the Kaimai Ranges near Mount Ngatamahinerua, at an altitude of 2460 feet (750 m). Twenty-three people were on board. Twenty-two were killed instantly; there is evidence that one person survived the impact but died shortly afterward. Three extra passengers were supposed to be on the flight, but changed their plans at the last minute. According to Civil Aviation Authority of New Zealand, Civil Aviation Authority investigators, a downdraft carried the aircraft below the level of the crests of the range, where under the very poor weather conditions prevailing at the time, the aircraft encountered an area of extreme turbulence from which it was i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lee Waves
In meteorology, lee waves are Earth's atmosphere, atmospheric stationary waves. The most common form is mountain waves, which are atmospheric internal gravity waves. These were discovered in 1933 by two German glider pilots, :de:Hans_Deutschmann, Hans Deutschmann and Wolf Hirth, above the Giant Mountains. They are Frequency, periodic changes of atmospheric pressure, temperature and orthometric height in a Air current, current of air caused by vertical displacement, for example orographic lift when the wind blows over a mountain or mountain range. They can also be caused by the surface wind blowing over an escarpment or plateau, or even by upper winds deflected over a thermal updraft or cloud street. The vertical motion forces periodic changes in speed and Boxing the compass, direction of the air within this air current. They always occur in groups on the Windward and leeward, lee side of the terrain that triggers them. Sometimes, mountain waves can help to enhance precipitation a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atmospheric Thermodynamics
Atmospheric thermodynamics is the study of heat-to-Work (physics), work transformations (and their reverse) that take place in the Earth's atmosphere and manifest as weather or climate. Atmospheric thermodynamics use the laws of classical thermodynamics, to describe and explain such phenomena as the properties of moist air, the formation of clouds, atmospheric convection, boundary layer meteorology, and vertical instabilities in the atmosphere. Atmospheric thermodynamic diagrams are used as tools in the forecasting of storm development. Atmospheric thermodynamics forms a basis for cloud microphysics and convection parametrization (climate), parameterizations used in numerical weather models and is used in many climate considerations, including convective-equilibrium climate models. Overview The atmosphere is an example of a non-equilibrium system. Atmospheric thermodynamics describes the effect of buoyant forces that cause the rise of less dense (warmer) air, the descent of more d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Low Level Windshear Alert System
A low-level windshear alert system (LLWAS) measures average surface wind speed and direction using a network of remote sensor stations, situated near runways and along approach or departure corridors at an airport. Wind shear is the generic term for wind differences over an operationally short distance (in relation to flight) which encompass meteorological phenomena including gust fronts, microbursts, vertical shear, and derechos. Background LLWAS compares results over its operating area to determine whether calm, steady winds, wind shifts (in relation to runways), wind gusts, divergent winds, sustained divergent winds (indicative of shear), or strong and sustained divergent winds (indicative of microbursts) are observed. A LLWAS master station polls each remote station every system cycle (nominally every ten seconds) and provides prevailing airport wind averages, runway specific winds, gusts, may set new wind shear alerts or microburst alerts and reset countdown timers of elaps ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Weather Service
The National Weather Service (NWS) is an Government agency, agency of the Federal government of the United States, United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the purposes of protection, safety, and general information. It is a part of the National Oceanic and Atmospheric Administration (NOAA) branch of the United States Department of Commerce, Department of Commerce, and is headquartered in Silver Spring, Maryland, within the Washington metropolitan area. The agency was known as the United States Weather Bureau from 1891 until it adopted its current name in 1970. The NWS performs its primary task through a collection of national and regional centers, and 122 local List of National Weather Service Weather Forecast Offices, Weather Forecast Offices (WFOs). As the NWS is an agency of the U.S. federal government, most of its products are in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NOAA
The National Oceanic and Atmospheric Administration (NOAA ) is an American scientific and regulatory agency charged with forecasting weather, monitoring oceanic and atmospheric conditions, charting the seas, conducting deep-sea exploration, and managing fishing and protection of marine mammals and endangered species in the US exclusive economic zone. The agency is part of the United States Department of Commerce and is headquartered in Silver Spring, Maryland. History NOAA traces its history back to multiple agencies, some of which are among the earliest in the federal government: * United States Coast and Geodetic Survey, formed in 1807 * Weather Bureau of the United States, formed in 1870 * Bureau of Commercial Fisheries, formed in 1871 (research fleet only) * Coast and Geodetic Survey Corps, formed in 1917 The most direct predecessor of NOAA was the Environmental Science Services Administration (ESSA), into which several existing scientific agencies such as the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
