- 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, ...
The point in an orbit at which any orbiting object, for example, planet, moon, artificial satellite, is farthest from the central object. Opposite of perigee. Compare perihelion.
Industry:Weather
The tide of reduced range when the moon is near apogee, its farthest point from the earth in its elliptical orbit.
Industry:Weather
The point on any orbit farthest from the center of attraction; the opposite of pericenter.
Industry:Weather
An observation of pressure, temperature, and relative humidity taken in the free atmosphere by means of an aerometeorograph (mounted under the wing of an aircraft). This term was abbreviated from “airplane observation,” and is rarely (if ever) used except in the above restricted sense. Compare aircraft observation, pilot report.
Industry:Weather
The Greek name for the east wind (“blowing from the sun”). According to legend, it brings light showers. On the Tower of the Winds at Athens it is represented by a young man carrying fruit and grain.
Industry:Weather
The point on the orbit of the earth (or any other body in orbit about the sun) that is farthest from the sun; the opposite of perihelion. At present, aphelion occurs about July 1, when the earth is about three million miles farther from the sun than at perihelion, but the seasons in which aphelion and perihelion fall undergo a cyclic variation with a period of twenty-one thousand years. The date of aphelion passage is advancing slowly (toward dates later in the calendar year) at a rate of about one-half hour each year. This is a consequence of the eastward rotation of the line of apsides at a rate of about 11 sec of arc per year and the precession of the equinoxes of about 50 sec of arc per year, for a total of 61. 9 sec of arc per year. See apocenter, apogee.
Industry:Weather
1. In a unidirectional antenna, that portion of the plane surface that is perpendicular to the direction of maximum radiation and through which the major part of the radiation passes. The physical aperture of a horn or parabolic antenna is identical with the actual area of the antenna face. Other types of apertures may be defined that are related to the effectiveness with which an antenna can remove energy from an incident radio wave (usually called effective area), and to the extent to which the intercepted energy is lost in heat or is reradiated. 2. In an opaque disk, the hole or window placed on either side of a lens to control the amount of light passing through.
Industry:Weather
