In this paper, we present a physics-driven procedural method for the interactive animation of realistic, single-layered cumulus clouds for the landscape-scale size. Our method employs the coarse units called parcels for the physics simulation and achieves procedural micro-level volumetric amplification based on the macro physics parameters. However, contrary to the previous methods which achieve amplification directly inside the parcels, we make use of the two-dimensional texture called cloud mapsto this end. This not only improves the shape and distribution of the cloud cover over the landscape but also boosts the animation efficiency significantly, allowing the overall approach to run at high frame rates, which is verified by the experiments presented in the paper.