Mechanisms of formation of aerosol and gaseous inhomogeneities in the turbulent atmosphere

Ž . Ž New mechanisms of formation of large-scale more than 100–200 m and small-scale about 1 . cm inhomogeneities in spatial distributions of aerosols, droplets and gaseous admixtures are discussed. The large-scale inhomogeneities are formed in the vicinity of the temperature inversion layers due to excitation of the large-scale instability. This effect is caused by additional nondiffusive turbulent flux of particles in the vicinity of the temperature inversion. The characteristic time of excitation of the instability of concentration distribution of particles varies in the range from 0.3 to 3 h depending on the particle size and parameters of both, the atmospheric turbulent boundary layer and the temperature inversion layer. The derived equation for the effective velocity of particles provides parameterization of these turbulence effects, and it can be directly incorporated into existing atmospheric models. Small-scale inhomogeneities are related with a self-excitation of fluctuations of inertial particles concentration in turbulent atmosphere. This effect is responsible for the intermittency in spatial distribution of particles and gases. q 2000 Elsevier Science B.V. All rights reserved.