This work presents a selective overview of natural fogs in terms of fog types, forms and states of occurrence, physical, micro-physical, chemical and dynamic properties, basic characterizing parameters, etc. In focus are related achievements and contributions reported mainly during the last decade and a half, as a result of both laboratory studies and field observations. Processes of homogeneous and heterogeneous nucleation are analyzed in the aspects of condensation, nuclei diversity and specifics, as related to the activation, growth and deposition of fog droplets. The effect is highlighted of the water vapor's partial pressure on the surface tension of the liquid water-air interface and the freezing point of the water droplets. Some problems and aspects of fog modeling, parameterization, and forecasting are outlined and discussed on the examples of newly developed relevant 1D/3D theoretical models. Important issues of fog impacts on the air quality, ecosystems, water basins, societal life, and human health are also addressed and discussed, particularly in cases of anthropogenically modified (chemical, radioactive, etc.) fogs. In view of reducing the possible negative effects of fogs, conclusions are drawn concerning the new demands and challenges to fog characterization imposed by the changing natural and social environment and the needs for new data on and approaches to more adequate observations of fog-related events.

.Two-wavelength (1064/532  nm) lidar observations of long-range transported Saharan dust present in the atmosphere over Sofia, Bulgaria, during a 4-day dust intrusion event in winter 2010, are reported. Aged desert aerosols are detected at altitudes up to 4 km above the sea level, within and above the boundary layer as mixed with other aerosols—representing the particular case under consideration. Optical, microphysical, and dynamical properties of dust aerosols are obtained and analyzed. Special attention is paid to retrieving and vertical profiling of dust backscatter-related Ångström exponents (BAEs), as well as to determining their frequency-count distributions. Obtained BAE values in the range 0.3 to 0.6 (±0.2) indicate domination of coarse particles in the near overmicron size range. Reasonability of coarse-mode-dominated dust size composition is substantiated, based on measurement and transportation-history analysis. The performed frequency-count statistics reveals dust BAE distributions asymmetrically extended to multimode distribution shapes, resulting from dust mixing with finer local aerosol fractions. Peculiarities and patterns of the aerosol dynamics at different stages of dust-loading event are revealed and discussed.

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