- 産業: Education
- Number of terms: 13055
- Number of blossaries: 0
- Company Profile:
Founded in 1879 and named after Texas' greatest hero General Sam Houston, Sam Houston State University is public shcool within the Texas state university system and located in Huntsville, Texas.
It's a multicultural institution that offers 79 bachelorette degree programs, 54 masters and five ...
NO<sub>x</sub> (pronounced "nox") are produced from high temperature combustion in air. They are nitrogen oxide and nitrogen dioxide (see above). Nitrogen monoxide is produced to varying degrees by all internal combustion engines that use atmospheric air as a source of oxygen.
Industry:Chemistry; Weather
O<sub>2</sub>, is found on Earth as a gas and constitutes about 20. 8% of the air we breathe. Elemental molecular oxygen consists of two oxygen atoms bonded together. A photochemical reaction of oxygen is (ultimately) responsible for the production of ozone in the stratosphere. Oxygen concentrations found in ice core samples (using isotopic <sup>16</sup>O/<sup>18</sup>O rations) have been used to determine past atmospheric levels of oxygen and have helped in determining past climates.
Industry:Chemistry; Weather
O<sub>3</sub>, is a molecule that consists of three oxygen atoms bonded together. The ozone layer in the stratosphere absorbs UV radiation and creates a warm layer of air in the stratosphere and is therefore responsible for the thermal structure of the stratosphere. Ozone that is present in the troposphere is mostly a result of anthropogenic pollution and therefore higher concentrations are found in urban areas. Ozone is involved with NO<sub>x</sub> in the photochemical production of many of the constituents of pollution environments (see nitrogen oxides and hydroxyl radicals. )
Industry:Chemistry; Weather
O<sup>. </sup> is the result of the oxygen molecule (O<sub>2</sub>) being photodissociated at a wavelength less than 242 nm. These two oxygen atoms react with O<sub>2</sub> (in the presence of a third body) and create ozone (O<sub>3</sub>).
Industry:Chemistry; Weather
Often used by humans to determine the historic chemical composition of the atmosphere; the source of the ice core is the snow which falls on the glacier which consolidates upon freezing and in which gas bubbles are trapped upon freezing. These data can be used to determine the atmospheric concentrations of a number of constituents at that time, for instance the important greenhouse gases. Ice core data from the European Project for Ice Coring in Antarctica show that present atmospheric concentrations of CO<sub>2</sub> and CH<sub>4</sub> are the highest in the past 800,000 years as determined in the so-called Dome C ice core.
Industry:Chemistry; Weather
OH, a molecule with an unpaired electron consisting of one hydrogen atom and one oxygen atom. This radical readily reacts with methane and other hydrocarbons in the atmosphere and can begin the process by which tropospheric oxygen is incorporated in a mechanism for the oxidation of NO to NO<sub>2</sub>. Photolysis of NO<sub>2</sub> yields atomic O and quickly ozone at tropospheric pressures. In urban environments this is a major source of ozone:
OH + CH<sub>3</sub>CH<sub>3</sub> ----> CH<sub>3</sub>CH<sub>2</sub><sup>. </sup>+ H<sub>2</sub>O
O<sub>2</sub> + CH<sub>3</sub>CH<sub>2</sub><sup>. </sup> ----> CH<sub>3</sub>CH<sub>2</sub>O<sub>2</sub><sup>. </sup>
NO + CH<sub>3</sub>CH<sub>2</sub>O<sub>2</sub><sup>. </sup> ----> CH<sub>3</sub>CH<sub>2</sub>O<sup>. </sup>+ NO<sub>2</sub>
NO<sub>2</sub> + hv ----> NO + O
O<sub>2</sub> + O + M ----> O<sub>3</sub> + M
The source of the hydroxyl radical in the atmosphere occurs primarily through the 1) photolysis of hydrogen peroxide, heat, and light and 2) the attack on water of an excited oxygen radical (created by the photolysis of ozone).
Industry:Chemistry; Weather
One of the components of an atmospheric air parcel, comprised of minute solids particles part of which is almost certainly water.
Industry:Chemistry; Weather
One of the most sensitive gas chromatographic detector for halogen-containing compounds like chlorofluorocarbons. Here's an animation. James Lovelock's early work with this detector led to the discovery that anthropogenic chlorofluorocarbons used most heavily in the Northern hemisphere were very long-lived and therefore well-mixed throughout the troposphere. Later work by Rowland and Molina suggested that CFCs also diffused into the stratosphere where their chlorine atoms could by freed by photolysis-CFC bond breaking by UV light. The result of this is the destruction of ozone molecules in the important ozone layer of the stratosphere.
Industry:Chemistry; Weather
Openings in the earth's crust that release molten rock, steam, reduced and oxidized compounds, and ash from within the earth's interior into the atmosphere.
Industry:Chemistry; Weather
Organisms utilize oxygen to break down components, derive energy, and generate needed biomolecules. Carbohydrates are cycled into water and carbon dioxide.
Industry:Chemistry; Weather
