Water clouds are expected to form in cool brown dwarfs (Y dwarfs) and giant planets with equilibrium temperatures near or below Earth's. Cloud distributions are controlled by microphysical processes such as nucleation and condensation, which hasn’t been considered in detail for water clouds in H/He atmospheres. The project's goal is to use the 1D Community Aerosol and Radiation Model for Atmospheres (CARMA) to investigate the microphysics of water clouds on temperate objects to constrain their typical particle sizes and vertical extent. The results are the first step towards constraining water clouds' impact on smaller and cooler worlds, such as K2-18b and habitable rocky planets from our simulated emission and reflected light spectra to inform future observations by instruments like the James Webb Space Telescope (JWST). This work has been published to ApJ.