Berechnung verschiedener physikalischer Konstanten von heterogenen Substanzen. I. Dielektrizitätskonstanten und Leitfähigkeiten der Mischkörper aus isotropen Substanzen

Bruggeman, D. A. G.

doi:10.1002/andp.19354160802

Cited by 634 publications

(634 citation statements)

References 15 publications

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“…We assume a mixture of water, ammonium nitrate and ammonium sulphate with no clear dominant component (The modelled concentrations of ammonium bisulphate or not-neutralised ammonium or nitrate are negligible). The formula for the effective refractive index is as follows (Aspnes et al, 1979;Bruggeman, 1935).…”

Section: Optical Modulementioning

confidence: 99%

Modelling the partitioning of ammonium nitrate in the convective boundary layer

Brugh

Henzing²,

Schaap³

et al. 2012

Atmos. Chem. Phys.

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Abstract. An explanatory model study is presented on semivolatile secondary inorganic aerosols on three clear days in May 2008 during the IMPACT campaign at the Cabauw tower in the Netherlands. A single column model in combination with the equilibrium aerosol model ISORROPIA is used. This model uses surface observations from IMPACT and calculates the gas-aerosol partitioning of ammonium nitrate. The calculated gas-aerosol equilibrium overestimates the gas phase fraction during daytime, and overestimates the aerosol phase fraction during night-time. This discrepancy can partly be solved when the approach of the gas-aerosol equilibrium is forced to proceed with a delay timescale of up to two hours. Although it is shown that the delay itself has a small effect, the most important effect is caused by the mixing of air from higher altitudes at which the equilibrium is shifted to the aerosol phase. Thus, vertical mixing is shown to have a significant influence on the calculated partitioning at the surface. On some occasions, the correspondence to the observed partitioning improves dramatically.Even though gas-aerosol partitioning of ammonium nitrate is not instantaneous, observations show that a different equilibrium in the upper boundary layer causes aerosol ammonium nitrate concentrations to increase with altitude. Our model calculates similar vertical gradients depending on the assumed speed of gas-aerosol equilibrium. The calculated optical properties of the aerosol show a similar behaviour. The aerosol optical properties depend on the aerosol size distribution both directly, because light scattering depends on particle size, and indirectly, because the equilibration timescale depends on the aerosol sizes. Future studies should therefore focus on a fully size-resolved treatment of the gas-aerosol partitioning.Finally, coarser-resolution models may treat the gasaerosol equilibrium of ammonium nitrate by calculating the equilibrium with a temperature and humidity sampled at a different altitude. We found that the equilibrium at an altitude of 200 m (night) up to 600 m (day) is representative for the partitioning of ammonium nitrate at the surface in the beginning of May 2008.

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Section: Optical Modulementioning

confidence: 99%

Modelling the partitioning of ammonium nitrate in the convective boundary layer

Brugh

Henzing²,

Schaap³

et al. 2012

Atmos. Chem. Phys.

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“…However, when the concentration of the inclusions, φ f , approaches unity, the permittivity of the mixture is not equal to the permittivity of the inclusions. Bruggeman [1935] has then derived a nonsymmetric expression where the shape of the inclusions was accounted for by the aspect ratio, p:…”

Section: Dielectric Propertiesmentioning

confidence: 99%

Structure–Property Relationships of Nanocomposites

et al. 2010

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“…These effective transition rates are self-consistently determined by the requirement that the difference between the propagator of the impurity and homogeneous problems should average to zero. 32,33,34,35,36,37,38,39,40 In anisotropic problems, two effective transition rates, one for each direction, are introduced. The effective frequency-dependent conductivities of the disordered system, σ 1 (u) and σ 2 (u), are proportional to the effective transition rates.…”

Section: Anisotropic Emamentioning

confidence: 99%

Universality of ac conduction in anisotropic disordered systems: An effective-medium-approximation study

Bustingorry

2005

Phys. Rev. B

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Anisotropic disordered systems are studied in this work within the random barrier model. In such systems the transition probabilities in different directions have different probability density functions. The frequency-dependent conductivity at low temperatures is obtained using an effective medium approximation. It is shown that the isotropic universal ac-conduction law, u = σ ln σ, is recovered if properly scaled conductivity ( σ) and frequency ( u) variables are used.

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Berechnung verschiedener physikalischer Konstanten von heterogenen Substanzen. I. Dielektrizitätskonstanten und Leitfähigkeiten der Mischkörper aus isotropen Substanzen

Cited by 634 publications

References 15 publications

Modelling the partitioning of ammonium nitrate in the convective boundary layer

Modelling the partitioning of ammonium nitrate in the convective boundary layer

Structure–Property Relationships of Nanocomposites

Universality of ac conduction in anisotropic disordered systems: An effective-medium-approximation study

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