  We discuss a new phenomenon of turbulent thermal diffusion associated with
turbulent transport of aerosols in the atmosphere and in laboratory
experiments. The essence of this phenomenon is the appearance of a nondiffusive
mean flux of particles in the direction of the mean heat flux, which results in
the formation of large-scale inhomogeneities in the spatial distribution of
aerosols that accumulate in regions of minimum mean temperature of the
surrounding fluid. This effect of turbulent thermal diffusion was detected
experimentally. In experiments turbulence was generated by two oscillating
grids in two directions of the imposed vertical mean temperature gradient. We
used Particle Image Velocimetry to determine the turbulent velocity field, and
an Image Processing Technique based on an analysis of the intensity of Mie
scattering to determine the spatial distribution of aerosols. Analysis of the
intensity of laser light Mie scattering by aerosols showed that aerosols
accumulate in the vicinity of the minimum mean temperature due to the effect of
turbulent thermal diffusion. Geophysical applications of the obtained results
are discussed.
