- 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, ...
A low that exists in approximately the same location most of the year, every year, and thus is evident on long-term average annual mean charts.
Industry:Weather
A low pressure circulation feature on monthly mean charts that is often evident in the same location during different years. Examples include the Aleutian low and the Icelandic low.
Industry:Weather
A local maximum in cloudiness, precipitation, and low-level convergence that occurs in a northwest–southeast oriented swath extending across southeastern Brazil and the western South Atlantic. This counterpart to the South Pacific convergence zone is strongest in summer.
Industry:Weather
A liquid-in-glass thermometer that uses an organic substance such as alcohol as the thermometric liquid. This type of thermometer has a very low freezing point and a high coefficient of expansion. The accuracy of thermometers using an organic liquid, however, is much less than that of thermometers using mercury. Spirit thermometers are used when the low freezing point is important, and in such special application as the minimum thermometer.
Industry:Weather
A line with its tangent at any point in a fluid parallel to the instantaneous velocity of the fluid at that point. The differential equations of the streamline may be written ''d''r × v = 0, where ''d''r is an element of the streamline and v the velocity vector; or in Cartesian coordinates, ''dx''/u = ''dy''/''v'' = ''dz''/ ''w'', where ''u'', ''v'', and ''w'' are the fluid velocities along the orthogonal ''x'', ''y'', and ''z'' axes, respectively. In steady-state flow the streamlines coincide with the trajectories of the fluid particles; otherwise, the streamline pattern changes with time. A two-dimensional wind-vector field may be completely specified by streamlines and isotachs. See free streamline; Compare trajectory.
Industry:Weather
A line of active thunderstorms, either continuous or with breaks, including contiguous precipitation areas resulting from the existence of the thunderstorms. The squall line is a type of mesoscale convective system distinguished from other types by a larger length-to-width ratio.
Industry:Weather
A lightning flash or stroke between a cloud and the ground that lowers positive charge from the cloud to the ground.
Industry:Weather
A line formed by the intersection of the surface of a sphere and a plane that does not pass through the center of the sphere. See great circle.
Industry:Weather
A lightning discharge of extraordinary peak luminosity when observed from space.
Industry:Weather
A level in the atmosphere where the velocity of the basic flow bears a direct relationship to the velocity of movement of an atmospheric disturbance embedded in the flow. This concept is most often applied as a subjective tool in forecasting the motion of surface pressure systems.
Industry:Weather
