Atmosphere troposphere

Although inert in the lower atmosphere (troposphere), the hilly halogenated CFCs and Halons diffuse into the upper stratosphere where they are photodissociated, ie, photolyzed, by the intense ultraviolet radiation. 

Ozone is a very reactive compound present in the upper atmosphere (stratosphere) and the lower atmosphere (troposphere). Whilst ozone is vital in the stratosphere, its presence at ground levels is a danger to human health and contributes to the formation of other pollutants. 

The relationship between dispersion and residence time is well-known in the lower atmosphere (troposphere), where concentrations of reactive gases, such as H20 and... 

Photochemically-generated radicals are encountered as reactive intermediates in many important systems, being a major driving force in the photochemistry of ozone in the upper atmosphere (stratosphere) and the polluted lower atmosphere (troposphere). The photochemistry of organic carbonyl compounds is dominated by radical chemistry (Chapter 9). Photoinitiators are used to form radicals used as intermediates in the chain growth and cross-linking of polymers involved in the production of electronic circuitry and in dental treatment. 

Methane is removed continually from the atmosphere by reaction with OH radicals (Section 8.3). In contrast, chlorofluorocarbons and related volatile compounds are inert under the conditions of the lower atmosphere (troposphere), so atmospheric concentrations of these refrigerants and solvents will tend to increase as long as releases continue. The chief concern over chlorofluorocarbons is that they are a major factor in destruction of the stratospheric ozone layer (Section 8.3). They have been banned under the Montreal Protocol of 1988, but it is important that whatever substitutes (inevitably greenhouse active) are introduced to replace them degrade relatively quickly in the troposphere to minimize any contribution they may be capable of making to greenhouse warming. 

Indirect Photolysis in the Atmosphere (Troposphere)—Reactions with Hydroxyl Radical (HO )... 

At wavelengths greater than 310 nm, the Huggins bands correspond to the limit of the O3 ultraviolet absorption, and in the visible region (410— 850 nm) the Chappuis bands play an important role leading to the 03 photodissociation in the lower part of the atmosphere, troposphere, and lower stratosphere. 

Waves (Atmospheric Dynamics) Radiation, Atmospheric Tropospheric Chemistry Weather Prediction, Numerical... 

Iodine-129 is produced in nuclear explosions of or Pu at approximate rates of 30 and 50 fiCi per kiloton (KT) TNT equivalent, respectively. The atmospheric transport and diffusion of radioiodine depend upon the initial height of the cloud and upon meteorological processes. A review of these factors was made by the United Nations Scientific Commitee on the Effects of Atomic Radiation (UNSCEAR, 1982). Fission products injected into the lower stratosphere have mean residence times of < 0.5 y while those from medium altitude explosions may have residence times of 2 years. The fission products that diffuse to the lower atmosphere (troposphere) are deposited (mainly by precipitation) in a matter of weeks. Dry deposition is a significant fraction of the total only in areas of low rainfall. 

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