Radiation inversion atmospheric mixing

The resultant O3 layer is critically important to life on Earth as a shield against LTV radiation. It also is responsible for the thermal structure of the upper atmosphere and controls the lifetime of materials in the stratosphere. Many substances that are short-lived in the troposphere (e.g. aerosol particles) have lifetimes of a year or more in the stratosphere due to the near-zero removal by precipitation and the presence of the permanent thermal inversion and lack of vertical mixing that it causes. 

A second inversion occurs at a height of about 90 km, at the mesopause, between the mesosphere and thermosphere, the heating in the latter is mainly due to absorption of far-UV solar radiation by dissociation of N2 and O2. These temperatirre inversions separate the atmosphere into distinct reservoirs, since they act as barriers to convective mixing material passes between troposphere and stratosphere mainly by the relatively slow process of diffusion. Local temperature inversions also occur in the lower troposphere to form regional reservoirs in which pollutant chemicals can build up to high concentrations a well-known local inversion phenomenon of this sort is that which occurs at elevations ranging from 300 m to 2 km over the Los Angeles basin in Southern California. 

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