Conclusions: The present paper was not aimed at reviewing existing NLTE prominence models, but rather to show
schematically ihe existing problems connected with such a models. There was no space to discuss the importance of plasma parameter determination for prominence MHD-modeling - for some particular questions see other reviews mentioned in this paper. Another interesting problem is the presence of oscillations (Suematsu et al., 1990). We should also stress that the present discussion was restricted only to stationary models, assuming that all atomic relaxations are much more rapid as compared to temporal variations of the plasma thermodynamic structure. In fact, for low hydrogen densities radiative recombination relaxatíon takes a rather long time (up to several tens of seconds - see Heinzel, 1991), which is to be compared to the typical life-time of prominence fine structures (Engvold, 1980). NLTE modeling of
temporal variations of prominence fine structures is an important new challenge and should be done simultaneously with new multiline observations in the UV (SOHO-mission), optical and IR (THEMIS) wavelength regions, made with sufficient spatial, spectral and temporal resolution.
We present the preliminary results of a study of the solar prominences observed at Lomnický Štít coronal station with the 20 cm coronagraph during the ascending phase of cycle 22. The observational material was processed and a catalogue of prominences was prepared. On the basis of this catalogue some statistical results were obtained. They concern mainly the latitudinal, longitudinal and time distributions of the prominences and their basic morphological characteristics.