- Industry: 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, ...
A theory of atmospheric dynamics that involves the quasigeostrophic approximation in the derivation of the quasigeostrophic equations. Quasigeostrophic theory is relatively accurate for synoptic-scale atmospheric motions in which the Rossby number is less than unity. However, it cannot accurately describe some atmospheric structures such as fronts or small strong low pressure cells as well as semigeostrophic theory.
Industry:Weather
A thick, nearly opaque fog. The term is often encountered as a simile, for example, “The fog was as thick as pea soup. ”
Industry:Weather
A thermometer housing that directs the ambient airflow to the thermometer around a sharp right-angle bend in the intake channel. See reverse flow thermometer housing.
Industry:Weather
A thermometer designed for use in measuring the temperature of seawater. One form of this instrument consists of a mercury-in-glass thermometer protected by a perforated metal case. This is used to measure the temperature of a sample of seawater. Another form consists of a mercury-in-glass thermometer surrounded by a metal case that forms a well around the bulb of the thermometer. When the thermometer is raised from the water, a sample is retained in the well for temperature measurement. See reversing thermometer, bucket thermometer.
Industry:Weather
A thermometer based on the principle that the velocity of a sound wave is a function of the virtual temperature of the medium through which it passes. By transmitting acoustic pulses in opposite directions between two transducers, the travel time difference can be used to infer the virtual temperature, provided that the wind speed across the acoustic path is known. Three-axis sonic anemometers, in addition to measuring three-dimensional winds, are also used as sonic thermometers. Sonic thermometers possess very short time constants and eliminate radiation error.
Industry:Weather
A thermodynamic function of state; the value of the mixing ratio of saturated air at the given temperature and pressure. This value may be read directly from a thermodynamic diagram. Without specific qualification, the saturation mixing ratio refers to saturation with respect to a plane surface of pure water. Saturation mixing ratios may also be specified with respect to a plane ice surface.
Industry:Weather
A theory that assumes eddy vorticity is conserved in turbulent air undergoing rapid stretching, while shear production of turbulence remains zero or unchanged. It is used to help predict the flow of turbulent air over hills and predicts that the vertical velocity variance should increase in the outer layer of accelerated winds flowing over a hill, while longitudinal velocity variance should decrease.
Industry:Weather
A theory originated by the Scandinavian school of meteorologists whereby a polar front, separating air masses of polar and tropical origin, gives rise to cyclonic disturbances that intensify and travel along the front, passing through various phases of a characteristic life history. This theory ushered in a new era of atmospheric analysis and remains an important basis of practical synoptic meteorology and weather forecasting even today.
Industry:Weather
A test of the reliability of estimate of statistical parameters. Such tests proceed by assuming that the estimates are not significant and are those to be expected from sampling a particular population, and then, from the properties of the population, determining the probabilities of such occurrences. The hypothesis (that the estimates are not significant) is rejected only when an observational result is found to be significant, that is, when the obtained result belongs to an objectively specified unfavorable class (critical region or rejection region) having a fixed, small probability of occurrence in random samples from the hypothesized population. When the result falls in the acceptance region, it is not significant and the hypothesis cannot be rejected. The boundaries of the classes are set in such a way that the total probability (unity) is appropriately divided between them, say 0. 95, 0. 05 or 0. 99, 0. 01. The probability assigned to the critical region, commonly either 0. 05 or 0. 01, is called the significance level. See chi- square test, Student's t-test, analysis of variance.
Industry:Weather
