  Understanding the limits of rocky planet habitability is one of the key goals
of current and future exoplanet characterization efforts. An intrinsic concept
of rocky planet habitability is the Habitable Zone. To date, the most widely
used estimates of the Habitable Zone are based on cloud-free, one-dimensional
(vertical) radiative-convective climate model calculations. However, recent
three-dimensional global climate modeling efforts have revealed that rocky
planet habitability is strongly impacted by radiative cloud feedbacks, where
computational expense and model limitations can prevent these tools from
exploring the limits of habitability across the full range of parameter space.
We leverage a patchy cloud one-dimensional radiative-convective climate model
with parameterized cloud microphysics to investigate Inner Edge limits to the
Habitable Zone for main sequence stars ($T_{\rm eff}$ = 2600 -7200K). We find
that Inner Edge limits to the Habitable Zone can be 3.3 and 4.7 times closer
than previous cloud-free estimates for Earth- and super-Earth-sized worlds,
respectively, depending on bulk cloud parameters (e.g., fractional cloudiness
and sedimentation efficiency). These warm, moist Inner Edge climates are
expected to have extensive cloud decks that could mute deep atmosphere spectral
features. To aid in rocky planet characterization studies, we identify the
potential of using $\rm{CO_{\rm 2}}$ absorption features in transmission
spectroscopy as a means of quantifying cloud deck height and cloud
sedimentation efficiency. Moist greenhouse climates may represent key yet
poorly understood states of habitable planets for which continued study will
uncover new insights into the search and characterization of habitable worlds.
