Fog is one of the meteorological events that helps reducing the horizontal and vertical visibility. Despite usefulness in agriculture and protection of plants against freezing; it has an important role in life and property damages in transportation sector. This natural and destructive event causes major difficulties in aviation and prevents flight operations. Generally, for fog dispersion and clearing weather, it is necessary to have knowledge about formation and types of fogs and investigate them in detail. New technologies for fog dissipation must then be applied for fog dispersion using cloud seeding technology. In this paper, after reviewing the processes of formation of fog and its physical construction, long term data and diagrams of foggy days in 30 cities of Iran were made and consequently zoning maps were produced. Field research results of fog dissipation in different regions of Iran were then discussed.Results of field tests indicate that cloud seeding method using liquid carbon dioxide by moving vehicle for super - cooled fog is one of the best methods and causes clearing weather and increasing visibility field after 30 minutes. The successful results of tests indicate that cloud seeding method could be applied for fog dissipation and clearing the atmosphere. In last part of the paper, numerical microphysical processes of super - cooled cloud seeding are discussed.