- 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, ...
In a lightning discharge, an increase in channel luminosity accompanied by a rapid electric field variation, itself called an M electric field change. The M components occur when the channel is already faintly luminous. Downward-moving leaders have not been observed to precede M components. The M components may be confused with branch components, the increases in channel luminosity that occur between each branch and the ground when the upward-propagating return stroke reaches that branch, since the higher branches are obscured by the cloud. The M component is a minor surge of current that reilluminates the channel in a negative cloud-to-ground flash. It may occur within microseconds or up to a few milliseconds of a return stroke. Evidence exists that M components are a result of the sequence of fast in-cloud negative leaders (K changes) contacting a conducting ground channel and renewed ground potential wave that reilluminate the channel.
Industry:Weather
An experimental series of meteorological satellites, launched between August 1964 and October 1978. Nimbus 1 was the first sun-synchronous, three-axis stabilized meteorological satellite. Nimbus satellites became the nation's principal platform for remote sensing research. Many of the instruments tested on Nimbus evolved into operational instruments used on other satellites.
Industry:Weather
1. A joint program of the U. S. Departments of Commerce, Defense, and Transportation during the 1980s and 1990s to develop and deploy a network of operational Doppler weather radars. 2. The popular name for the radar itself, the WSR-88D weather radar, which became the operational network radar for the U. S. National Weather Service, U. S. Air Force, and Federal Aviation Administration during the early and middle 1990s. The nominal transmitted wavelength of the WSR-88D is 10. 5 cm (S band) and the nominal circular beamwidth is 0. 95°.
Industry:Weather
A system of mechanics based on Newton's laws of motion. The salient characteristics of Newtonian mechanics are that mass and energy are separately conserved, all physical variables can take on a continuous set of values, the state of a system at any instant uniquely determines its state at any later instant (determinism), and interactions at a distance are instantaneous. Compare quantum theory.
Industry:Weather
A set of three postulates first set forth by Sir Isaac Newton in the middle of the seventeenth century. According to the first law (the law of inertia), a body (point mass) remains at rest or in a state of uniform motion unless acted on by a force, where the position of the body is specified relative to an inertial reference frame. The second law states that the time rate of change of (linear) momentum of a body is equal to the force on the body; Newton took momentum to be the product of mass and velocity, which is only an approximation valid at speeds much less than that of light. Finally, the third law states that if two bodies exert forces on each other, they are equal in magnitude and opposite in direction. Although apparently simple and unambiguous, Newton's laws have engendered considerable discussion over the extent to which some of them are mere definitions (e.g., of inertial reference frame, mass, and force) or are true laws in the sense of being subject to experimental verification. Deshnbvnmbmngjpite the ambiguity of Newton's laws, they have proven to be an efficient way of describing the physical world (within limits) and form the basis for the equations of motion of fluids.
Industry:Weather
As stated by Newton, the exponential decrease of temperature with time of a body cooling in a fluid. Newton's law of cooling is an approximation valid under restricted conditions, not a universal law of nature.
Industry:Weather
A fluid in which the stress tensor is proportional to the rate of deformation, that is, a fluid satisfying the Navier–Stokes equations. See viscous force.
Industry:Weather
A seasonal western boundary current through Vitiaz Strait and along the northern coast of New Guinea. The current flows northwestward from April to November and is then a link between the northern branch of the South Equatorial Current and the Halmahera Eddy. It reverses during December to March, opposing the New Guinea Coastal Undercurrent underneath, when the Philippines experience monsoon winds blowing from the northeast in the Northern Hemisphere and from the northwest south of the equator.
Industry:Weather
A western boundary current and part of the equatorial current system in the Pacific Ocean. It flows northwestward through Vitiaz Strait and along the northern coast of New Guinea. It receives its water from the northern branch of the South Equatorial Current and is the major source of the Equatorial Undercurrent.
Industry:Weather
