- 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. The wave motion of the tides. 2. In popular usage, any unusually high (and therefore destructive) water level along a shore. It usually refers to either a storm surge or tsunami.
Industry:Weather
1. The variation of horizontal wind speed and direction (or of horizontal components of wind) with height such as would be measured with a sounding. 2. The equations describing the variation of wind with height. A classic example is the logarithmic wind speed profile in the surface layer of the atmospheric boundary layer. Compare shear. 3. See velocity distribution.
Industry:Weather
1. The true vertical distance above mean sea level. 2. Same as corrected altitude.
Industry:Weather
1. The range within which values of a variable lie, as in the diurnal or annual variation. 2. Same as declination.
Industry:Weather
1. The poleward limit of tree growth. See arctic tree line, tree line. 2. In mountainous regions, the line above which climatic conditions do not allow the upright growth of trees.
Industry:Weather
1. The periodic rising and falling of the earth's oceans and atmosphere. It results from the tide-producing forces of the moon and sun acting upon the rotating earth. This disturbance actually propagates as a wave through the atmosphere and along the surface of the waters of the earth. Atmospheric tides are always so designated, whereas the term “tide“ alone commonly implies the oceanic variety. Sometimes, the consequent horizontal movement of water along the coastlines is also called “tide,” but it is preferable to designate the latter as tidal current, reserving the name tide for the vertical wavelike movement. See equatorial tide, neap tide, spring tide, tropic tide. 2. See rip current, red tide, storm tide.
Industry:Weather
1. The period of any time-harmonic (or sinusoidal) physical quantity governed by a wave equation. 2. The time interval between successive wave crests or troughs. However, in a random sea, a variety of interpretations of this are possible. A commonly used definition is the so-called zero-upcrossing period, which is the time interval between two successive upcrossings of the mean water level. See wave frequency, wave height, wave length.
Industry:Weather
1. The period during which the earth completes one revolution around the sun. This has several interpretations, as follows. 1) Sidereal year: time of true revolution around the sun, that is, the time it takes the earth (as seen from the sun) to reappear at the same fixed star, equal to 365. 2564 mean solar days or 365 days, 6 hours, 9 minutes, 10 seconds; 2) Tropical year (also called mean solar year, ordinary year): the time measured from one vernal equinox to the next, that is, the apparent revolution of the sun through the zodiac, equal to 365. 2422 mean solar days or 365 days, 5 hours, 48 minutes, 46 seconds (this is not constant but decreases by about 5 seconds in one thousand years. ); and 3) Calendar year: fixed by the Gregorian calendar of 365 days in ordinary years and 366 days in leap years. See day. 2. Any arbitrary 12-month period selected for a special purpose, such as the water year. See Also climatological year, farmer's year, grower's year.
Industry:Weather
1. The greatest distance in a given direction at which it is just possible to see and identify with the unaided eye 1) in the daytime, a prominent dark object against the sky at the horizon, and 2) at night, a known, preferably unfocused, moderately intense light source. After visibilities have been determined around the entire horizon circle, they are resolved into a single value of prevailing visibility for reporting purposes. There are inherent difficulties with the conventional requirement that visibility markers be both detected and recognized. The more rigorously defined concept of the visual range avoids reference to recognition; thus, if the recognition requirement were dropped, the visibility could be defined as a subjective estimate of visual range. For most practical purposes, it can be defined that way now. Daytime estimates of visibility are subjective evaluations of atmospheric attenuation of contrast, while nighttime estimates represent attempts to evaluate something quite different, namely, attenuation of flux density. Thus, visibility data must be regarded as falling into two distinct classes, those obtained by day, and those by night. In U. S weather observing practice, it is the value as obtained and reported by an observer or by an automatic weather station. See surface visibility, control-tower visibility, runway visual range, night visual range. 2. The clarity with which an object can be seen.
Industry:Weather
1. The frequency of any time-harmonic (or sinusoidal) physical quantity governed by a wave equation. 2. In simple terms, the number of wave crests that pass a fixed point per second of time, equal to the inverse of the wave period. However, in a random sea, a variety of interpretations of this are possible. A commonly used definition is the so-called zero-upcrossing frequency, which is the number of successive upcrossings of the mean water level that pass a fixed point per second of time. See wave height, wave length.
Industry:Weather
