- 업종: 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, ...
A higher altitude (6–15 km) turbulence phenomenon occurring in cloud-free regions, associated with wind shear, particularly between the core of a jet stream and the surrounding air. It is most common near upper air fronts and the tropopause, and can often affect an aircraft without warning. Clear-air turbulence also frequently occurs close to towering cumulus clouds (usually within 30 km), and near mountains. Airflow disrupted by mountains and other terrain can undulate in waves of turbulence for 1000 km or more. See also aircraft turbulence.
Industry:Weather
A unit of energy defined as that amount of energy required to raise the temperature of one gram of water by one degree Celsius (the gram-calorie or small calorie), equal to 4. 1855 joules. The kilogram calorie or large calorie (Kcal, kg-cal, or Cal) is 1000 times as large as a calorie.
Industry:Weather
A temperature scale with the ice point of water at 0° and the boiling point at 100°. Conversion to the Fahrenheit temperature scale is according to the formula °C = 5/9 (°F − 32). See Celsius temperature scale.
Industry:Weather
A hydrodynamical paradox arising from the neglect of viscosity in the steady flow of a fluid around a submerged solid body.
According to this paradox, the submerged body would offer no resistance to the flow of an inviscid fluid and the pressure on the surface of the body would be symmetrically distributed about the body. This paradox may be traced to the neglect of the viscous forces, which are indirectly responsible for fluid resistance by modifying the velocity field close to a solid body.
Industry:Weather
A forecast for the ordinary daily range, for periods of from 12 to 48 hours in advance.
Forecasts of this type usually express in some detail, for specific geographical areas, the expected day-to-day sequence of all the aspects of weather that materially affect human activity and well- being. See short-range forecast; compare medium-range forecast, long-range forecast, extended forecast.
Industry:Weather
Maximum temperature in the course of a continuous time interval of 24 hours (usually midnight to midnight local time).
Industry:Weather
The downward movement of pollutants or smoke plumes immediately to the lee of flow obstacles, such as buildings, bluffs, or smokestacks.
This downwash is caused by wake turbulence or lee cavity circulations generated by the obstacle and brings higher-concentration pollutants down toward the ground. Stack downwash occurs when the average vertical effluent velocity ''w''<sub>0</sub> out of the top of the smokestack is less than 1.5 times the mean wind speed ''M'' at stack top. The average height decrease of the pollutant plume centerline is of order 2''D''[(''w''<sub>0</sub>/''M'') − 1.5], where ''D'' is the diameter of the top of the smokestack.
Industry:Weather
A turbulence closure of one-and-a-half statistical order, where forecast equations are retained for mean wind and temperature, for wind and temperature variance, and for molecular dissipation of wind and temperature. Other unknowns such as fluxes or variables of higher statistical order are approximated or parameterized as a function of the mean quantities, variances E, and dissipation rates ε.
Industry:Weather
For turbulent flow, the property of having the spatial, temporal and ensemble averages all converge to the same mean. This can only be true if the flow is stationary and homogenous. As a consequence, the autocorrelation of an ergodic flow variable is zero as either the averaging length, time, or number of realizations goes to infinity. See ensemble average.
Industry:Weather
