Shortwave Radiative Effects of Unactivated Aerosol Particles in Clouds

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  • a Department of Atmospheric Sciences, University of Washington, Seattle 98195
  • | b Department of Civil Engineering, University of Washington, Seattle 98195
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Abstract

Clouds in some polluted areas may contain high concentrations of anthropogenic aerosol particles. The possible role of these particles in perturbing the optical and dynamical properties of the clouds is an important question for climate studies. The direct radiative effects of unactivated aerosol particles in stable stratus clouds have been calculated at λ = 0.5 μm. Several simplifying assumptions have been made relating the behavior of such particles in the high humidity environment within the cloud to their physicochemical make-up. It is shown that the energy absorbed by particles within the clouds may be, for realistic concentrations, comparable to the latent heat released and thus may play a significant role in cloud dynamics in some areas. These results are shown to be relatively insensitive to the assumptions about the particle properties within the cloud.

Abstract

Clouds in some polluted areas may contain high concentrations of anthropogenic aerosol particles. The possible role of these particles in perturbing the optical and dynamical properties of the clouds is an important question for climate studies. The direct radiative effects of unactivated aerosol particles in stable stratus clouds have been calculated at λ = 0.5 μm. Several simplifying assumptions have been made relating the behavior of such particles in the high humidity environment within the cloud to their physicochemical make-up. It is shown that the energy absorbed by particles within the clouds may be, for realistic concentrations, comparable to the latent heat released and thus may play a significant role in cloud dynamics in some areas. These results are shown to be relatively insensitive to the assumptions about the particle properties within the cloud.

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