- 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, ...
Precipitation composed of white or translucent ice crystals, chiefly in complex branch hexagonal form and often agglomerated into snowflakes. For weather-observing purposes, the intensity of snow is characterized as 1) light when the visibility is 1 km (5/8 statute mile) or more; 2) moderate when the visibility is less than 1 km (5/8 statute mile) but not more than 1/2 km (5/16 statute mile); and 3) heavy when the visibility is less than 1/2 km (5/16 statute mile).
Industry:Weather
Precipitation consisting of a mixture of rain and wet snow. It usually occurs when the temperature of the air layer near the ground is slightly above freezing. The British term for this mixture is sleet (which has a different meaning in the United States).
Industry:Weather
Precipitation from a convective cloud. Showers are characterized by the suddenness with which they start and stop, by the rapid changes of intensity, and usually by rapid changes in the appearance of the sky. In weather observing practice, showers are always reported in terms of the basic type of precipitation that is falling, that is, rain showers, snow showers, sleet showers. In aviation weather observations, these are encoded RW, SW, and EW, respectively. See airmass shower.
Industry:Weather
Precipitation in the form of liquid water drops that have diameters greater than 0. 5 mm, or, if widely scattered, the drops may be smaller. The only other form of liquid precipitation, drizzle, is to be distinguished from rain in that drizzle drops are generally less than 0. 5 mm in diameter, are very much more numerous, and reduce visibility much more than does light rain. For observing purposes, the intensity of rainfall at any given time and place may be classified as 1) “light,” the rate of fall varying between a trace and 0. 25 cm (0. 10 in. ) per hour, the maximum rate of fall being no more than 0. 025 cm (0. 01 in. ) in six minutes; 2) “moderate,” from 0. 26 to 0. 76 cm (0. 11 to 0. 30 in. ) per hour, the maximum rate of fall being no more than 0. 076 cm (0. 03 in. ) in six minutes; 3) “heavy,” over 0. 76 cm (0. 30 in. ) per hour or more than 0. 076 cm (0. 03 in. ) in six minutes. When rain gauge measurements are not readily available to determine the rainfall intensity, estimates may be made according to a descriptive system set forth in observing manuals.
Industry:Weather
Positive vorticity advection along an isothermal surface.
Industry:Weather
Portable observation systems that can be set up and operated unattended at field sites to measure, for example, temperature, winds, humidity, surface pressure, solar and infrared radiation, rainfall, and sometimes more specialized variables such as sensible and latent heat fluxes, momentum flux, surface radiation temperature, net radiation, soil moisture, and soil heat flux. They are often self-contained, powered by solar cells and batteries, and able to transmit data to a base station from remote locations. Typically they are deployed in a network from a few kilometers to tens of kilometers apart to provide baseline data for mesoscale multifaceted observational studies.
Industry:Weather
Popular term applied to all activities designed to increase, through any artificial means, the amount of precipitation released from a cloud. The techniques of cloud seeding have been studied carefully and extensively, especially since V. J. Schaefer's discovery of the effect of dry ice on supercooled clouds.
Industry:Weather
Poisonous to plants. Sensitive plants react to pollutant chemicals by suppression of plant growth or reduced productivity.
Industry:Weather
