- 行业: Weather
- Number of terms: 60695
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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, ...
An expendable meteorological instrument package, often borne aloft by a free-flight balloon, that measures, from the surface to the stratosphere, the vertical profiles of atmospheric variables and transmits the data via radio to a ground receiving system. Radiosondes typically measure temperature, humidity, and, in many cases, pressure. Radiosonde temperature sensors generally measure temperature-induced changes in the electrical resistance, capacitance, or voltage of a material. Radiosonde humidity sensors can be substances that respond in a known way to changes in ambient humidity or instruments that directly measure a characteristic of the air that is dependent on its water vapor content. Radiosonde pressure sensors are typically aneroid cells, a part of which flexes in proportion to pressure changes. Some radiosondes do not measure pressure, but pressure data are calculated from the hypsometric equation using temperature, humidity, and height data. Some radiosondes also measure wind speed and direction. See rawinsonde.
Industry:Weather
An exceptionally dry mass of air formed by subsidence and usually found aloft but occasionally reaching the earth's surface during extreme subsidence processes. It is often found above tropical maritime air, bounded by the trade-wind inversion.
Industry:Weather
An evaporation pan the top of which is covered by wire mesh or screening to prevent animals from drinking the water and debris from falling into it. The screening reduces air circulation and insolation, and increases the pan coefficient.
Industry:Weather
An evaluation of the state of the atmosphere as observed from a point at the surface of the earth, as opposed to an upper-air observation. This term is applied mainly to observations that are taken for the primary purpose of preparing surface synoptic charts. Major types of surface observation are synoptic weather observation, aviation weather observation, and marine weather observation. Climatological observations may also be included.
Industry:Weather
An evaluation of the radiation from the sun that reaches the observation point. The observing instrument is usually a pyrheliometer or pyranometer. Two types of such observations are taken. The more common consists of measurements of the radiation reaching a horizontal surface, consisting of both radiation from the sun (direct solar radiation) and that reaching the instrument indirectly by scattering in the atmosphere (diffuse sky radiation). The second type of observation involves the use of an equatorial mount that keeps the instrument pointed directly at the sun at all times. The sensitive surface of the instrument is normal to the path of solar radiation and is shielded from indirect radiation from the sky.
Industry:Weather
An established line or transect of measurements of snow water equivalent across a snow field in representative mountainous terrain, where appreciable snow accumulates, to monitor seasonal snowpack. Although intended to be measured over a distance of several hundred meters, in practice snow courses may consist of four or so individual measurements. The measurements are used for runoff prediction and for assessing the potential for flooding or drought, and they are also used in longer- term climatological studies. Along the snow course, core samples are taken periodically (often monthly) throughout the snow season. Approximately 300 snow courses are operated over the western United States.
Industry:Weather
An environmental lapse rate greater than the dry-adiabatic lapse rate, such that potential temperature decreases with height.
Industry:Weather
An empirical unit hydrograph, developed for ungauged watersheds, that is based upon measurable physical basin characteristics.
Industry:Weather
An empirical method of finding universal relationships between variables that are made dimensionless using appropriate scaling factors. The dimensionless groups of variables are called Pi groups and are found using a dimensional analysis method known as Buckingham Pi theory. Similarity methods have proved very useful in the atmospheric boundary layer, where the complexity of turbulent processes precludes direct solution of the exact governing equations. See mixed-layer similarity, local free-convection similarity, local similarity.
Industry:Weather
