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Ellrod Index
In meteorology the Ellrod index is a technique for forecasting clear-air turbulence (CAT). It is calculated based on the product of horizontal deformation and vertical wind shear derived from numerical model forecast winds aloft. The deformation predictors are calculated using following information. * ''Shearing deformation'': : DSH=\frac + \frac . * ''Stretching deformation'': : DST = \frac - \frac. Where ''u'' and ''v'' are horizontal components of the wind. * ''Total deformation'' equals to: : DEF = \sqrt . * ''Convergence'': : CVG = -(\frac + \frac) * ''Vertical wind shear'': : VWS = \frac And the resulting index is given by: : EI = VWS \times (DEF + CVG) To correspond to clear-air turbulence pilot reports the following table can be used: See also * Aviation Weather Center The Aviation Weather Center (AWC) provides weather information and forecasts for air flights over United States territory and at certain altitudes for global traffic. It works with customers, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clear-air Turbulence
In meteorology, clear-air turbulence (CAT) is the turbulent movement of air masses in the absence of any visual clues, such as clouds, and is caused when bodies of air moving at widely different speeds meet. The atmospheric region most susceptible to CAT is the high troposphere at altitudes of around as it meets the tropopause. Here CAT is most frequently encountered in the regions of jet streams. At lower altitudes it may also occur near mountain ranges. Thin cirrus clouds can also indicate high probability of CAT. CAT can be hazardous to the comfort, and occasionally the safety, of air travelers. CAT in the jet stream is expected to become stronger and more frequent because of climate change, with transatlantic wintertime CAT increasing by 59% (light), 94% (moderate), and 149% (severe) by the time of doubling. Detection Clear-air turbulence is usually impossible to detect with the naked eye and very difficult to detect with a conventional radar, with the result that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wind Shear
Wind shear (or windshear), sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizontal wind shear. Vertical wind shear is a change in wind speed or direction with a change in altitude. Horizontal wind shear is a change in wind speed with a change in lateral position for a given altitude. Wind shear is a microscale meteorological phenomenon occurring over a very small distance, but it can be associated with mesoscale or synoptic scale weather features such as squall lines and cold fronts. It is commonly observed near microbursts and downbursts caused by thunderstorms, fronts, areas of locally higher low-level winds referred to as low-level jets, near mountains, radiation inversions that occur due to clear skies and calm winds, buildings, wind turbines, and sailboats. Wind shear has significant effects on the control ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pilot Report
A pilot report or PIREP is a report of actual flight or ground conditions encountered by an aircraft. Reports commonly include information about atmospheric conditions (like temperature, icing, turbulence) or airport conditions (like runway condition codes or ground equipment failures). This information is usually relayed by radio to the nearest ground station, but other options (e.g. electronic submission) also exist in some regions. The message would then be encoded and relayed to other weather offices and air traffic service units. Although the actual form used to record the PIREP may differ from one country to another, the standards and criteria will remain almost the same. At a minimum the PIREP must contain a header, aircraft location, time, flight level, aircraft type and one other field. In recent years, a PIREP will also include UA or UUA used to identify the PIREP as routine or urgent. Included data Mandatory *UA or UUA used to identify the PIREP as routine or urge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aviation Weather Center
The Aviation Weather Center (AWC) provides weather information and forecasts for air flights over United States territory and at certain altitudes for global traffic. It works with customers, such as commercial airlines, and international partners to improve flight safety and efficiency. It is one of the components of the National Centers for Environmental Prediction of the National Weather Service (NWS) of the United States. Responsibilities and Products Each local NWS office issues Terminal aerodrome forecasts (TAFs) for airports under its area of responsibility. These forecasts are only valid for 10 nautical miles (18.5 km) around the airfield. AWC forecasts, in text and chart, conditions over all of the continental United States from the surface to over 20 km altitude (Aviation Area forecast). These include freezing level, icing, wind and turbulence levels, cloudy areas and thunderstorms at various altitudes. It does the same for high altitudes around the world ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteorological Indices
Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did not begin until the 18th century. The 19th century saw modest progress in the field after weather observation networks were formed across broad regions. Prior attempts at prediction of weather depended on historical data. It was not until after the elucidation of the laws of physics, and more particularly in the latter half of the 20th century the development of the computer (allowing for the automated solution of a great many modelling equations) that significant breakthroughs in weather forecasting were achieved. An important branch of weather forecasting is marine weather forecasting as it relates to maritime and coastal safety, in which weather effects also include atmospheric interactions with large bodies of water. Meteorological phenom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
