Motions in the outer layers of the 27-day Cepheid T Monocrotis

Radial velocities and Ha profiles are presented for the entire cycle of T Mon. Several interpretations in terms of rising or falling material are presented, but no simple physical model can be derived and fully justified. The metallic absorption lines show the same depth effects as seen for SV Vul. The lines formed deepest in the atmosphere are accelerated first and the lines formed at highest layers feel the running wave last. The sodium D lines are resolved near minimum light into stellar and interstellar components. Key words: radial velocity - cepheids - variable stars