- المجال: Weather
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The American Meteorological Society promotes the development and dissemination of information and education on the atmospheric and related oceanic and hydrologic sciences and the advancement of their professional applications. Founded in 1919, AMS has a membership of more than 14,000 professionals, ...
The study of measuring and recording the direction and speed (or force) of the wind, including its vertical component. Systematic records of wind direction as indicated by wind vanes were begun in Italy in 1650 and in England in 1667. The speed of the wind was first observed by noting the rate at which light substances are carried along by the air; it is now determined by means of anemometers.
Industry:Weather
General name for an instrument that measures the inclination of the wind to the horizontal plane.
Industry:Weather
Ice attached to the beds of streams, lakes, and shallow seas, irrespective of its nature of formation. On clear, cold nights in relatively still water, anchor ice may form directly on submerged objects. It also develops in supercooled water if turbulence is sufficient to maintain uniform temperature at all depths, in which case a spongy mass of frazil accumulates on objects exposed to rapid flow, and later deposition fills in the pores and creates solid ice. When the water temperature increases to above 0°C, the ice rises to the surface, often carrying with it the object on which it had accumulated. Sometimes anchor ice is erroneously called ground ice, a term which should be reserved for bodies of more or less clear ice in frozen ground.
Industry:Weather
An approximate system of equations for deep and shallow atmospheric convection. The equations are derived under the assumptions that the percentage range in potential temperature is small and that the timescale is set by the Brunt–Väisälä frequency. Acoustic waves are thereby filtered - hence the term anelastic, meaning elastic energy is not allowed. If the vertical scale of motion is small compared to the depth of an adiabatic atmosphere, the anelastic equations reduce to the Boussinesq equations for shallow convection.
Industry:Weather
Chart depicting the geographical distribution of meteorological conditions with the aid of fronts, isobars, etc.
Industry:Weather
A super-pressure balloon suspended below a zero-pressure balloon to permit the zero-pressure balloon to survive night-time cooling without the expenditure of ballast and daytime warming without release of lifting gas. The lift decreases during ascent and decreases during descent, providing stability to the zero- pressure balloon.
Industry:Weather
A statistical technique for resolving the total variability of a set of data into systematic and random components. The analysis of variance is fundamentally a statistical estimating and/or testing procedure. It estimates the components of variance due to systematic and random causes, and it leads to significance tests of these components. The statistical assumptions required for a valid test are more stringent than those for estimating the components of variance.
Industry:Weather
1. In synoptic meteorology, a detailed study of the state of the atmosphere based on observations, usually including a separation of the entity into its component patterns and involving the drawing of families of isopleths for various elements. Thus, the analysis of synoptic charts may consist, for example, of the drawing and the interpretation of the patterns of wind, pressure, pressure change, temperature, humidity, clouds, and hydrometeors, all based on observations taken or forecast simultaneously. 2. A procedure to project the state of the atmosphere (or any system) as known from a finite set of imperfect, irregularly distributed observations onto a regular grid or to represent the atmospheric state by the amplitude of standard mathematical functions. The grid and/or functional expansion allows for subsequent forecasts by numerical integration or for easy diagnostic study. An analysis may be looked upon as a space–time interpolation system. Essential ingredients of analysis are a background field, usually a short-range forecast although persistence and climatology are options, a forecast model, knowledge of the relative error of the many different observational platforms employed as well as knowledge of the error in the background field, and the spatial covariance of the various errors. Real time computational considerations generally limit the complexity of methods used. Historically important is the subjective hand analysis, that is, drawing isobars on a map given mean sea level pressure at a set of observing stations. Most analysis systems in the past have been at best 3D spatial analyses; time–space analysis systems have recently emerged at operational prediction centers. A long series of analyses is of great utility for studying the behavior of the atmospheric climate system. See reanalysis, variational objective analysis.
Industry:Weather
