  Using the results of a high-resolution, cosmological hydrodynamical
re-simulation of a supercluster-like region we investigate the physical
properties of the gas located along the filaments and bridges which constitute
the so-called cosmic web. First we analyze the main characteristics of the
density, temperature and velocity fields, which have quite different
distributions, reflecting the complex dynamics of the structure formation
process. Then we quantify the signals which originate from the matter in the
filaments by considering different observables. Inside the cosmic web, we find
that the halo density is about 4-6 times larger than in the neighbouring
region; the bremsstrahlung X-ray surface brightness reaches at most 10e-16
erg/s/cm^2/armin^2; the Compton-y parameter due to the thermal
Sunyaev-Zel'dovich effect is about 10e-6; the reduced shear produced by the
weak lensing effect is ~ 0.01-0.02. These results confirm the difficulty of an
observational detection of the cosmic web. Finally we find that projection
effects of the filamentary network can affect the estimates of the properties
of single clusters, increasing their X-ray luminosity by less than 10% and
their central Compton-y parameter by up to 30% cent.
