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Atop the troposphere is the tropopause, which is the functional atmospheric border that demarcates the troposphere from the stratosphere. As such, because the tropopause is an inversion layer in which air-temperature increases with altitude, the temperature of the tropopause remains constant. [2] The layer has the largest concentration of nitrogen.
About 90% of total ozone in the atmosphere is in the stratosphere, and 10% is in the troposphere. [5] Although ground-level ozone is less concentrated than stratospheric ozone, it is of concern because of its health effects. [6] Ozone in the troposphere is considered a greenhouse gas, and as such contribute to global warming.
Ozone in the troposhere is determined by photochemical production and destruction, dry deposition and cross-tropopause transport of ozone from the stratosphere. [2] In the Arctic troposphere, transport and photochemical reactions involving nitrogen oxides and volatile organic compounds (VOCs) as a result of human emissions also produce ozone resulting in a background mixing ratio of 30 to 50 ...
The dominating parameter influencing ozone generation efficiency is the gas temperature, which is controlled by cooling water temperature and/or gas velocity. The cooler the water, the better the ozone synthesis. The lower the gas velocity, the higher the concentration (but the lower the net ozone produced).
Three forms (or allotropes) of oxygen are involved in the ozone-oxygen cycle: oxygen atoms (O or atomic oxygen), oxygen gas (O 2 or diatomic oxygen), and ozone gas (O 3 or triatomic oxygen). [15] Ozone is formed in the stratosphere when oxygen gas molecules photodissociate after absorbing UVC photons. This converts a single O 2 into two atomic ...
Although the temperature may be −60 °C (−76 °F; 210 K) at the tropopause, the top of the stratosphere is much warmer, and may be near 0 °C. [24] The stratospheric temperature profile creates very stable atmospheric conditions, so the stratosphere lacks the weather-producing air turbulence that is so prevalent in the troposphere.
The formation rate is primarily a function of temperature and the residence time of nitrogen at that temperature. At high temperatures, usually above 1300 °C (2600 °F), molecular nitrogen ( N 2 ) and oxygen ( O 2 ) in the combustion air dissociate into their atomic states and participate in a series of reactions.
Ozone-oxygen cycle in the ozone layer. The Earth's ozone layer formed about 500 million years ago, when the neoproterozoic oxygenation event brought the fraction of oxygen in the atmosphere to about 20%. [7] The photochemical mechanisms that give rise to the ozone layer were discovered by the British physicist Sydney Chapman in 1930.