- 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 altitude that corresponds to a given value of atmospheric pressure according to the ICAO standard atmosphere. For aircraft flying above 18 000 feet MSL, it is the indicated altitude of a pressure altimeter at an altimeter setting of 1013. 2 mb (29. 92 in. Of mercury); therefore, it is the indicated altitude above the 1013. 2-mb constant-pressure surface. Aircraft flying below 18 000 feet MSL use the current altimeter setting as measured at the nearest airport and reported by air traffic control.
Industry:Weather
The altitude of an aircraft as determined by radar-type radio altimeter; thus, the actual distance from the nearest terrain feature. For all practical purposes, the radar altitude over oceans is equal to the height above mean sea level.
Industry:Weather
The albedo of a surface when the incident radiation is isotropic. Spherical albedos are also used as the average of the plane albedo over all sun angles, or as the effective albedo of an entire planet.
Industry:Weather
The albedo of a flat surface. In contrast to the spherical albedo, this usually refers to the albedo of a flat surface illuminated only by direct solar radiation from a specified direction.
Industry:Weather
The air temperature decrease near the surface when the surface is colder than the air. For a nocturnal SBL over land, it can be measured as the potential temperature difference between the residual layer and the air temperature near the ground. Inversion strength increases as greater cooling continues over longer times and decreases with increasing wind speed and turbulent mixing.
Industry:Weather
The air and other gases in spaces in the soil; specifically, that which is found within the zone of aeration. The aeration of soil by exchange with the free air above is a continuing process, but is accelerated by pressure and temperature changes (See normal aeration). The composition of soil air is modified by bacterial activity and by chemical processes due to the action of oxygen and carbon dioxide in the presence of soil moisture. Generally speaking, soil air contains more carbon dioxide than does free air. In addition to the gases originating in the soil, the following may be present in the soil atmosphere in measurable quantities: ammonia, hydrogen sulfide, methane, and other hydrocarbons resulting from decay of organic materials. Traces of helium, radon, thoron, and actinon from radioactive processes also diffuse through the soil layers into the atmosphere by the process of exhalation.
Industry:Weather
That portion of a lightning discharge that radiates strongly in the frequency interval 10–30 kHz. The physical source is generally identified with the return stroke in flashes to ground and the K change in the case of intracloud flashes.
Industry:Weather
That portion of the electromagnetic spectrum having wavelengths longer than about 10 cm.
Industry:Weather
That portion of the infrared spectrum containing significant radiant energy from the sun. Wavelengths range from 720 nm to about 4 μm. See'' also'' near-infrared.
Industry:Weather
That pressure (force per unit area) recorded when the height of a column of mercury is reduced to standard gravity and temperature. It is the pressure exerted by a column of mercury 760 mm high, of density 13 595. 1 kg m<sup>−3</sup>, subject to a gravitational acceleration of 9. 80665 m s<sup>−2</sup>, and equals 1013. 25 hPa. This is a sea level consideration at 45°N latitude.
Industry:Weather
