Journal ArticleDOI
The free radical chemistry of cloud droplets and its impact upon the composition of rain
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In this article, the authors simulate the free radical chemistries of the gas phase and aqueous phase within a warm cloud during midday solar fluxes and demonstrate that the scavenging of OH and HO2 from cloud droplets can represent a major source of free radicals to cloud water provided the accommodation or sticking coefficient for these species impinging upon water droplets is not less than 0.0001.Abstract:
Calculations are presented that simulate the free radical chemistries of the gas phase and aqueous phase within a warm cloud during midday. It is demonstrated that in the presence of midday solar fluxes, the heterogeneous scavenging of OH and HO2 from the gas phase by cloud droplets can represent a major source of free radicals to cloud water, provided the accommodation or sticking coefficient for these species impinging upon water droplets is not less than 0.0001. The aqueous-phase of HO2 radicals are found to be converted to H2O2 by aqueous-phase chemical reactions at a rate that suggests that this mechanism could produce a significant fraction of the H2O2 found in cloud droplets. The rapid oxidation of sulfur species dissolved in cloudwater by this free-radical-produced H2O2 as well as by aqueous-phase OH radicals could conceivably have a significant impact upon the chemical composition of rain.read more
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Journal ArticleDOI
Heterogeneous chemistry and tropospheric ozone
TL;DR: In this article, it is recommended that standard O 3 models include in their chemical mechanisms the following reaction probability parameterizations for reactive uptake of gases by aqueous aerosols and clouds: γ HO 2 =0.2 (range 0.1-1) for HO 2 → 0.5 H 2 O 2, γ NO 2 =10 −4 (10 −6 −10 −3 ) for NO 2 → HNO 3, and γ N 2 O 5 → 2 H NO 3.
Journal ArticleDOI
Photodissociation in the atmosphere: 1. Actinic flux and the effects of ground reflections and clouds
TL;DR: In this paper, it was shown that photodissociation rate coefficients inside clouds, and particularly inside cloud droplets, can frequently exceed the clear-sky values, in contrast to current usage in cloud chemistry models, due to the ∼2 cos θ factor incurred in the actinic flux when the solar beam is scattered and diffused into nearly isotropic light.
Journal ArticleDOI
The oxidizing capacity of the earth's atmosphere: probable past and future changes.
TL;DR: Models and the observational network for oxidants are improving, but validation of global models is still at an early stage and positive and negative trends possible for OH and H2O2.
Journal ArticleDOI
The nitrate radical: Physics, chemistry, and the atmosphere
Richard P. Wayne,Ian Barnes,P. Biggs,John P. Burrows,Carlos E. Canosa-Mas,Jens Hjorth,G. Le Bras,Geert K. Moortgat,Dieter Perner,G. Poulet,G Restelli,Howard Sidebottom +11 more
TL;DR: A review of the state of the art in the field of chemistry of the NO 3 radical is presented in this paper, with a focus on the relationship between the laboratory and the atmospheric studies.
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Heterogeneous and Multiphase Chemistry in the Troposphere
TL;DR: In this paper, the authors make a distinction between reactions on solids (heterogeneous reactions) and those occurring in liquid droplets (multiphase reactions) is convenient for understanding, describing, and including them in models of the troposphere.
References
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Atmospheric OCS measurements on Project Gametag
TL;DR: In the spring of 1978, carbonyl sulfide measurements were made at Drexel University in Philadelphia, Pennsylvania, and on Project (global atmospheric measurements experiment of tropospheric aerosols and gases).
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Absorption spectra and reaction kinetics of NO2, N2O3, and N2O4 in aqueous solution
Avner. Treinin,Elie Hayon +1 more
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Reaction kinetics of nitrogen dioxide with liquid water at low partial pressure
Y. N. Lee,Stephen E. Schwartz +1 more
TL;DR: In this article, a gas-liquid reaction model has been studied for 1 x 10/sup -7/ less than or equal to P/sub NO2 less than and equal to 8 x 10 /sup -4/ atm.
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Carbonate radical in flash photolysis and pulse radiolysis of aqueous carbonate solutions
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On the relation between pH and the chemical composition in atmospheric precipitation
TL;DR: In this article, the relation between the pH and the total amount of acid or of base respectively is studied based on chemical analyses of some 2, 000 rainwater samples, and a regular deviation is observed between the empirically found and theoretically calculated relation.