Journal ArticleDOI
The free radical chemistry of cloud droplets and its impact upon the composition of rain
TLDR
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
Citations
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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.
Journal ArticleDOI
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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Electrical conductivity techniques for studying the kinetics of radiation-induced chemical reactions in aqueous solutions
TL;DR: In this paper, a review of the work of the author and his co-workers in the field of conductivity measurements on pulse-irradiated aqueous solutions is presented.
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Oxidation of ferrous ions by perhydroxyl radicals
TL;DR: In this article, it was shown that the mechanism of the oxidation of ferrous ions is though to consist of simple electron transfer, and the difference in rate between H2O and D2O solution is attributed to differences between free energies of hydration in the two solvents.
Journal ArticleDOI
The two-dimensional diagnostic model for tropospheric OH - An uncertainty analysis
William L. Chameides,A. Tan +1 more
TL;DR: In this paper, a two-dimensional diagnostic model for tropospheric ozone was proposed to predict the global ozone abundance as a function of latitude and altitude, which can also be applied to budget studies of species which interact with ozone, such as CH4, CO, and O3.
Journal ArticleDOI
Oxidation of SO 2 and Other Atmospheric Gases by Ozone in Aqueous Solution
TL;DR: In this paper, it was shown that ozone is formed by photolysis of oxygen in the stratosphere and diffuses down through the troposphere to be destroyed at the Earth's surface.
Journal ArticleDOI
Evidence for aqueous phase hydrogen peroxide synthesis in the troposphere
Brian G. Heikes,Allan L. Lazrus,Gregory L. Kok,S. M. Kunen,B. W. Gandrud,Sonia N. Gitlin,P. D. Sperry +6 more
TL;DR: In this article, the authors investigated the effects of different species of atmospheric constituents on the aqueous collection and measurement of H2O2 vapor, and found that the amount of insolubility of these constituents was higher than the amount initially present as vapor.