The highly irregular nature of most photospheric magnetic fields is analyzed here, trying to emphasize the connection between photospheric fluctuations and those existing in the solar wind. It is discussed how the magnetic flux conservation in sunspots demands penumbrae pervaded by kilometer-wide irregularities. The diagnosis of this type of tiny scales requires special tools having degrees of freedom for optically-thin magnetic irregularities. One of such tools is introduced here, to be subsequently applied to the quiet Sun. It turns out to reproduce the observed Zeeman induced polarization, despite the fact that the polarization is frequently very abnormal. The kind of irregular atmosphere that the inversion technique favors seems to provide a consistent picture of the quiet Sun magnetism. ©1999 American Institute of Physics.