On the impact of the magnitude of Interstellar pressure on physical
  properties of Molecular Cloud
  Recently reported variations in the typical physical properties of Galactic
and extra-Galactic molecular clouds (MCs), and in their ability to form stars
have been attributed to local variations in the magnitude of interstellar
pressure. Inferences from these surveys have called into question two
long-standing beliefs that the MCs : 1 are Virialised entities and (2) have
approximately constant surface density i.e., the validity of the Larson's third
law. In this work we invoke the framework of cloud-formation via collisions
between warm gas flows. Post-collision clouds forming in these realisations
cool rapidly and evolve primarily via the interplay between the Non-linear Thin
Shell Instability (NTSI), and the self-gravity. Over the course of these
simulations we traced the temporal evolution of the surface density of the
assembled clouds, the fraction of dense gas, the distribution of gas column
density (NPDF), and the Virial nature of the assembled clouds. We conclude,
these physical properties of MCs not only exhibit temporal variation, but their
respective peak-magnitude also increases in proportion with the magnitude of
external pressure, $P_{ext}$. The velocity dispersion in assembled clouds
appears to follow the power-law, $\sigma_{gas}\propto P_{ext}^{0.23}$. Also,
the power-law tail at higher densities becomes shallower with increasing
magnitude of external pressure, for magnitudes, $P_{ext}/k_{B}\lesssim 10^{7}$
K cm$^{-3}$, at higher magnitudes such as those typically found in the Galactic
CMZ ($P_{ext}/k_{B} > 10^{7}$ K cm$^{-3}$), the power-law shows significant
steepening. Thus while our results are broadly consistent with inferences from
various recent observational surveys, it appears, MCs hardly exhibit a unique
set of properties, but rather a wide variety, that can be reconciled with a
range of magnitudes of pressure between 10$^{4}$ K cm$^{-3}$ - 10$^{8}$ K
cm$^{-3}$.
