Intermittent distribution of inertial particles in turbulent flows

We consider inertial particles suspended in an incompressible turbulent flo w. Because of particles' inertia their flow is compressible, which leads to fluctuations of concentration significant for heavy particles. We show tha t the statistics of these fluctuations is independent of details of the vel ocity statistics, which allows us to predict that the particles cluster on the viscous scale of turbulence and describe the probability distribution o f concentration fluctuations. We discuss the possible role of the clusterin g in the physics of atmospheric aerosols, in particular, in cloud formation .