Low clouds and fogs observations by polarization lidar

In the paper some polarization investigations of objects and phenomena in the planetary boundary layer of the atmosphere are presented. The observations described were performed by a ground-based lidar over the region of Sofia city where various industrial enterprises exist along with a heavy transport and aerial communications. The changes in the optical characteristics of fog and snow depending on the changes in the microphysical characteristics of the respective objects caused by the meteorological situation changes. The dynamics of the cloud system formation during a warm front advection is observed. The lidar data give possibility of following the base of two of the clouds layers along with the changes in their polarization characteristics. Differences between the optical properties of the aerosol near the clouds base and top are established. The depolarization coefficient changes depending on the penetration depth allows the phase composition of the cloud layers to be determined.