Abstract: Atmospheric variables are often decomposed into balanced and unbalanced components that represent, respectively, low-frequency variability and high-frequency dispersive waves. Such a decomposition underlies theory, modeling and forecasting, but traditionally does not account for phase changes of water, since the latter create a piecewise operator that changes across phase boundaries (dry versus cloudy air). Here we present a balanced-unbalanced decomposition for moist dynamics with phase changes and rainfall, and discuss some applications for understanding canonical weather phenomena and water transport.