exerted by the hot and dense intracluster medium (ICM) can effectively remove the cold gas supply, truncating the gas disc and quenching star formation, in massive cluster galaxies passing through the centre of rich clusters in about one crossing time ($\sim 10^9$yr), while the interstellar gas of a massive galaxy may never be completely stripped if the galaxy moves on a tangential orbit or is member of a poor cluster. Repeated high-velocity encounters (harassment) of cluster galaxies can destroy the fragile disc of dwarf galaxies, but not significantly affect the structure of a giant galaxy.

The development of large spectroscopic surveys such as the Sloan Digital Sky Survey (SDSS), plus the availability of panoramic far ultra-violet – far infra-red (FUV–FIR) data from the [*GALEX*]{} and [*Spitzer*]{} space telescopes have allowed the impact of environment on SF to be quantified in unprecedented detail. In these studies, however, the environment and its characteristics are usually treated as ‘static parameters’. While the galaxies move across the cluster, field and filament environments (experiencing different ram pressures, encountering other galaxies and possibly being involved in merging), the cluster potential well, the galaxy density as well as the ICM are usually not considered ‘time-dependent’. Of course, 