- 行业: 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, ...
1. In general, water flow in which gravitational forces predominate. 2. In glaciology, glacial movement in which ice flow results from the downslope component of gravitational force.
Industry:Weather
1. An accumulation of water and mud released from ground ice by spring thawing. 2. A small mound of fresh soil material, formed by frost action. (Glossary of Permafrost and Related Ground-Ice Terms, National Research Council of Canada, NRCC 27952, Technical Memorandum No. 142, 1988. )
Industry:Weather
1. An accumulation of frazil in a body of water. 2. The initial stage of ice formation in turbulent water. Frazil ice consists of platelets or discs roughly 1 mm in diameter. These small platelets clump together to form shuga, and eventually (if sufficient open water area exists) form pancake ice. Frazil ice may form in open water leads and around the ice margins in the Arctic, but it is most common in the Antarctic. It may also form in turbulent rivers in winter, particularly in rapids.
Industry:Weather
1. According to U. S. Weather observing practice, a fog that hides less than 0. 6 of the sky and does not extend to the base of any clouds that may lie above it. As an obstruction to vision in an aviation weather observation, ground fog is encoded GF. 2. See radiation fog.
Industry:Weather
1. Alteration of any part of the earth's surface by passage of a glacier, chiefly by glacial erosion or deposition; distinguish from glacierization. 2. As used in many texts, particularly with respect to the ice ages, same as glacierization, for example, “Pleistocene glaciation. ” 3. The transformation of cloud particles from supercooled water drops to ice crystals. Thus, a cumulonimbus cloud is said to have a glaciated upper portion.
Industry:Weather
1. A very light ice fog, that is, same as ice-crystal haze, arctic mist. 2. See ice crystal.
Industry:Weather
1. A sudden, brief increase in the speed of the wind. It is of a more transient character than a squall and is followed by a lull or slackening in the wind speed. Generally, winds are least gusty over large water surfaces and most gusty over rough land and near high buildings. According to U. S. Weather observing practice, gusts are reported when the peak wind speed reaches at least 16 knots and the variation in wind speed between the peaks and lulls is at least 9 knots. The duration of a gust is usually less than 20 s. 2. With respect to aircraft turbulence, a sharp change in wind speed relative to the aircraft; a sudden increase in airspeed due to fluctuations in the airflow, resulting in increased structural stresses upon the aircraft. 3. (Rare. ) Same as cloudburst.
Industry:Weather
1. A point (or line) on a scale used for reference or comparison purposes. In the calibration of meteorological thermometers, for example, the fiducial points are 100°C (212°F) and 0°C (32°F), which correspond to the boiling point and ice point of water at standard pressure (760 mm of mercury). 2. A reference point of known location on a map, graph, or image used to set the position for overlays of similar maps, graphs, or images.
Industry:Weather
1. A device for combining ratings of several variable factors into numerical classes of fire danger. 2. A graphical aid used in fire-weather forecasting to calculate the degree of forest-fire danger (or burning index). Commonly in the form of a circular slide rule, the fire-danger meter relates numerical indices of 1) the seasonal stage of foliage, 2) the cumulative effect of past precipitation or lack thereof (buildup index), 3) the measured fuel moisture, and 4) the speed of the wind in the woods. The fuel moisture is determined by weighing a special type of wooden stick that has been exposed in the woods, its weight being proportional to its contained water.
Industry:Weather
1. A curve the coordinates of which are the values of the variable and the frequency of occurrence. It is often presented as a histogram. Compare probability distribution. 2. (Also called frequency curve. ) The relationship between the probability that a threshold is exceeded and the threshold. In a graphical representation, the curve is often plotted with frequency or probability on the vertical y axis and the corresponding rainfall or flood flow values on the horizontal x axis.
Industry:Weather
