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The relationship between liquid water content (LWC) and visibility (VIS) in a fog was examined by a field measurement of LWC values at a clean location of the meteorological observatory Sodankylä (Finland) and in a polluted region at the meteorological observatory Milešovka (Czech Republic). Furthermore, the use of a simple regression fog model to determine LWC from VIS is examined by comparing well-known relationships with the measurement results.The results show that the verbal characterization of environment (clean, mild polluted, polluted) is insufficient to calculate the LWC values from visibility. It is necessary to establish an additional criterion based on quantitative fog characteristics or to determine the site-related equation from the previous LWC and VIS measurement.

The paper summarizes results of chemical analyses of fog and rime water samples. The samples were collected at Milesovka, the Czech meteorological observatory. The input data set contains the samples acquired during 234 fogs and 14 rime events. The fog and rime samples were collected in the period of 2000-2004. Methods employed for sampling fog and rime water and differences in the pollutant concentrations are described. The following components were analyzed: conductivity, acidity (pH), cations Na + , K + , NH 4 + , Mg 2+ , Ca 2+ , and anions F -, Cl -, NO 3 -, SO 4 2-. The attention was exclusively devoted to the precipitation originating in fogs (no falling precipitation particles were considered). Differences in the relative content of selected ions in the annual average samples of rime and fog are presented together with their absolute values. The importance of rime contributions to total precipitation amounts is demonstrated by maximum values of the rime weight detected at the Milesovka Observatory. The absolute maximum of 52.3 kg m −2 was registered at Milesovka Mt. on December 28, 2002.