MICRO-STRUCTURED MAGNETIC ATMOSPHERES

Asymmetrical Stokes profiles are produced if the photospheric magnetic and velocity fields are structured on scales smaller than the mean-fr ee-path of the photons. Here we put forward a compact analytical expre ssion for the radiative transfer equation in this case. Explicitly, mi cro-variations of the magnetic field strength and the velocity are con sidered. The existence of micro-structures might have serious implicat ions on the techniques currently used to measure solar magnetic fields . For example, we show the failure of the relationship employed to cal ibrate magnetographs.