- المجال: 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, ...
A technique to determine the water level in a well, lake, or any water body with a free surface, using the principle of measuring back-pressure in a pressurized air line that extends downward below the water surface to a known elevation. When air under pressure is introduced to the air line, it forces the water in the line out until the air bubbles from the bottom of the tube. At this time, noting the air pressure in the line, the pressure is converted mathematically into a height-of-water volume. Air-line sounding is a very effective means of measuring water levels in very deep wells.
Industry:Weather
Light scattered into quasi-horizontal viewing directions by the atmosphere's molecules and small particles (usually excluding fog and raindrops). On clear to partly cloudy days, airlight is dominated by singly scattered sunlight, but it also includes multiply scattered sunlight from clouds, the surface, and the clear sky. A more restrictive definition limits airlight to clear days; a less restrictive one does not limit the elevation angles at which airlight is seen. As haze concentrations increase, airlight radiances increase near the horizon, although not without limit. Increased airlight reduces a distant object's contrast, thus reducing its visibility. At sufficiently large horizontal optical thicknesses, airlight reduces this contrast below the threshold contrast, and the object is then visually indistinguishable from its surroundings. Airlight and the artistic term aerial perspective are related, since airlight causes the reduced contrast associated with increased distance to an object. Airlight is distinct from airglow that originates in the upper atmosphere.
Industry:Weather
The quasi-steady radiant emission from the upper atmosphere over middle and low latitudes, to be distinguished from the sporadic emission of auroras that occur over high latitudes. Airglow is a photochemical luminescence (or chemiluminescence) arising from chemical reactions in the upper atmosphere. Many of these reactions leave molecules and atoms in excited states from which they can radiate at certain well-defined wavelengths. Emissions from molecular oxygen O2, atomic oxygen O, sodium Na, and the hydroxyl radical OH are especially prominent, and measurements of airglow intensity by spectrometric techniques have provided a great deal of information about upper-atmospheric dynamics and chemistry.
Industry:Weather
The ratio of air in a fuel mixture relative to the exact amount required to convert all of a hydrocarbon fuel to water and carbon dioxide (known as a stoichiometric mixture). If the air content is higher than stoichiometric, the mixture is said to be fuel-lean; if the air content is less, the mixture is fuel-rich.
Industry:Weather
A code used to summarize, by category, actual or forecast ceiling and visibility conditions at an airfield. Each ceiling and visibility category is assigned a specific color.
Industry:Weather
The transfer of electric charge from the positively charged atmosphere to the negatively charged earth. This current is made up of the air–earth conduction current, a point-discharge current, a precipitation current, a convection current, and miscellaneous smaller contributions. Of these, the air–earth conduction current is by far the largest. This is not just true locally, but throughout the world where there are no thunderstorms occurring, which is estimated to be 80%–90% percent of the earth. The existence of this quasi-steady current in fair weather and the observed maintenance of the earth's net negative charge are both better established than the nature of the supply current, which must replenish the positive charge in the upper atmosphere and the negative charge on the earth.
Industry:Weather
A communication method where data are sent from an aircraft to a satellite that relays the data to another location. This method extends line-of-sight communications.
Industry:Weather
That part of the air–earth current contributed by the electrical conduction of the atmosphere itself. It is represented as a downward current in storm-free regions all over the world. The conduction current is the largest portion of the air–earth current, far outweighing the contributions made by the precipitation current and convection current, which are zero in storm-free regions. Its magnitude is approximately 3 × 10−12 amperes (A) m−2, or about 1800 A for the entire earth. Such observations of the vertical variation of the conduction current as have been made indicate that it is approximately uniform throughout the depth of the troposphere, a condition that is consistent with the generally accepted view that the conduction current flows from a positively charged conducting region in the lower ionosphere downward to the negatively charged earth. Only in areas of temporarily disturbed weather does the conduction current become replaced by reverse flow. Accumulating evidence points to the conclusion that the conduction current continues to exist only because of the action of thunderstorms scattered at all times over the earth, which supply the positive charge to the upper atmosphere and negative charge to the earth. See supply current.
Industry:Weather
The making of detailed weather observations or investigations from aircraft in flight. The aircraft may either fly regularly scheduled flights along a fixed route (usually over areas not covered by land or ship stations), or it may fly a special mission to survey a particular weather phenomenon such as a thunderstorm or tropical cyclone. The RECCO code is used to report weather reconnaissance data.
Industry:Weather
