- 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, ...
Certain plants (mostly leguminous) that are capable of biological conversion of molecular dinitrogen (atmospheric nitrogen, or N<sub>2</sub>) to organic combinations (nitrogen fixation), or to forms usable in biological processes, through the action of symbiotic rhizobia (bacteria) in the root nodules.
Industry:Weather
The incorporation of gaseous molecular nitrogen, N<sub>2</sub>, into nitrogenous compounds. Abiotic fixation of N<sub>2</sub> occurs via lightning and photochemical conversion in the atmosphere. Biotic fixation of N<sub>2</sub> is done by specialized bacteria that construct the hemoglobin-like enzymes necessary to cleave the strong triple bond of molecular nitrogen.
Industry:Weather
Family of compounds in which nitrogen is bound to oxygen. The most abundant is nitrous oxide, formula N<sub>2</sub>O, which is relatively unreactive. Nitric oxide (NO) and nitrogen dioxide (NO<sub>2</sub>) are highly reactive, and are present in much lower amounts in the atmosphere. Together, NO and NO<sub>2</sub> are classed as odd nitrogen, or active nitrogen.
Industry:Weather
A brown gas, formula NO<sub>2</sub>, found at all levels in the atmosphere. In the troposphere it photodissociates to give free oxygen atoms, which then form ozone, and is thus a key player in local and regional air pollution events. In the stratosphere it participates in catalytic ozone destruction cycles, but also forms stable nitrate reservoir species that ameliorate ozone loss.
Industry:Weather
(Symbol N. ) A colorless, tasteless, odorless gaseous element, atomic number 7, atomic weight 14. 007. It is the most abundant constituent of the atmosphere, amounting to 78. 09% by volume of dry air. The molecular formula for nitrogen gas is N<sub>2</sub>; its molecular weight is 28. 016. Nitrogen enters the atmosphere from volcanoes and from the decay of organic matter. It is removed from the atmosphere by certain natural nitrogen-fixing bacteria for use in plant life processes. Free nitrogen is very inactive, but can be broken down by high-energy reactions such as occur in lightning, high temperature combustion, or in the upper atmosphere. Nitrogen-containing compounds are very reactive and play integral roles in the production and destruction of ozone in the atmosphere. Atomic nitrogen, N, occurs in significant quantities only at altitudes above about 100 km.
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A continuous series of natural processes by which nitrogen successively passes through air, soil, and organisms involving principally organism decay, nitrogen fixation, nitrification, and denitrification. See nitrogen-fixing plants.
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A stable crystalline form of nitric acid and water, consisting of three molecules of water for every molecule of nitric acid. Polar stratospheric clouds (type I) may be in the form of NAT at least part of the time.
Industry:Weather
A colorless gas, formula NO, the most common form of nitrogen emitted into the atmosphere, either by fuel combustion or due to natural emissions. Nitric oxide is interconverted with nitrogen dioxide fairly readily in the atmosphere, resulting in catalytic cycles leading to ozone formation in the troposphere and ozone loss in the stratosphere.
Industry:Weather
The process of converting reduced nitrogen (as ammonia or ammonium) to its more oxidized forms (nitrite or nitrate ions). It is a two-step process, with each step carried out by distinct groups of bacteria. The first step is the oxidation of ammonia to nitrite, and the second is oxidation of nitrite to nitrate.
Industry:Weather
A very soluble, acidic gas, formula HNO<sub>3</sub>, the end product of the oxidation of emitted gases. It is a major component of acidic precipitation in continental regions. In the clean background troposphere, its removal in precipitation acts as a sink for odd hydrogen and nitrogen compounds and limits the formation of ozone.
Industry:Weather
