In this work it is shown how absolute simultaneity of spatially distinct events can be established by means of a general criterion based on isotropically propagating signals and how it can be consistently preserved also when operating with Lorentz-like coordinate transformations between moving frames. The specific invariance properties of these transformations of coordinates are discussed, leading to a different interpretation of the physical meaning of the transformed variables with respect to their prevailing interpretation when associated with the Lorentz transformation. On these basis, the emission hypothesis of W. Ritz is then applied to justify the outcomes of the Fizeau experiment, thanks to the introduction of an additional hypothesis regarding the influence of turbulence on the refractive index of the moving fluid. Finally, a test case to investigate the validity of either the Galilean or the Relativistic velocity composition rule is presented. Such test relies on the aberration of the light coming from celestial objects due to the motion of the observer, and on the analysis of the results obtained by applying the two different formulas to process the data of the observed positions, as measured in the moving frame, in order to determine the actual un-aberrated location of the source.