An analysis of observation material concerning fog occurrence in Hornsund collected by seven whole-year expeditions of the Polish Academy of Sciences' to Spitsbergen in 1957—58, 1978—1980, 1981—1985 is presented. The frequencies of fog occurrence in Hornsund during a year and in particular months are compared with respective frequencies calculated for Norwegian stations in Svalbard. Data from the Poland territory are also quoted. The dependences of the fog frequency in Hornsund on air masses advection, circulation type, direction and speed of local winds, time of observation and temperature are shortly analyzed. The periods with long-lasting fogs (exampled by synoptic situations that favor them) are discussed more precisely. A short description of main meteorologie processes favoring the occurrence of fog in this part of Spitsbergen is presented.

This paper gives the daily values of chosen meteorological elements measured at the Polar Station of the Polish Academy of Sciences at Hornsund, during the Vlth Expedition of the Polish Academy of Sciences to Spitsbergen. The tables give average daily values of air temperature, relative humidity, atmospheric pressure, cloud amount and wind speed, daily amounts of precipitation and bright sunshine, extreme temperature values, maximum instantaneous wind speed and snow cover thickness for all the days in the period under study.