2000A&A...358..575J

We discuss the influence of the non-thermal velocity (micro-turbulence) on the formation of chromospheric lines in the atmospheres of late type dwarfs. A review of previous work shows a variety of different approaches to the problem leading to different atmospheric structures and consequently different computed line profiles. In that light, we re-examine the formation of the Hydrogen Balmer lines and Nai D lines using twelve different distributions of the micro-turbulent velocity throughout the atmosphere. Our results show a wide range of possible line shapes. Using the analogy with the solar case and the latest results of the non-thermal component widths as derived from instruments on-board SOHO we model Hα and the NaID lines in an active dMe star Gl 616.2.