  Exploiting the data of the Grism Lens-Amplified Survey from Space (GLASS), we
characterize the spatial distribution of star formation in 76 high star forming
galaxies in 10 clusters at 0.3< z <0.7. All these galaxies are likely
restricted to first infall. In a companion paper we contrast the properties of
field and cluster galaxies, whereas here we correlate the properties of
H{\alpha} emitters to a number of tracers of the cluster environment to
investigate its role in driving galaxy transformations. H{\alpha} emitters are
found in the clusters out to 0.5 virial radii, the maximum radius covered by
GLASS. The peak of the H{\alpha} emission is offset with respect to the peak of
the UV-continuum. We decompose this offsets into a radial and tangential
component. The radial compo- nent points away from the cluster center in 60% of
the cases, with 95% confidence. The decompositions agree with cosmological
simulations, i.e. the H{\alpha} emission offset correlates with galaxy velocity
and ram-pressure stripping signatures. Trends between H{\alpha} emitter
properties and surface mass density distributions and X-ray emissions emerge
only for unrelaxed clusters. The lack of strong correlations with the global
environment does not allow us to identify a unique environmental effect
originating from the cluster center. In contrast, correla- tions between
H{\alpha} morphology and local number density emerge. We conclude that local
effects, uncorrelated to the cluster-centric radius, play a more important role
in shaping galaxy properties.
