Effect of trapped lee wave interference on the shape of wave clouds

Abstract This study investigates the effects of trapped lee wave interference on wave clouds over the southern Kanto region of Japan using camera images, satellite images, meteorological observations, a model analysis dataset, and numerical simulations based on Weather Research and Forecasting models. The wave clouds of interest had a NNE–SSW strike with cloud rows separated by approximately 15 km. They exhibited a lenticular irregular cloud base in the target area. The results of the numerical simulation and terrain‐modification experiments suggested that the wave clouds of the observed shapes were not formed by trapped lee waves excited by individual mountain ranges alone, but by constructive and destructive interference among trapped lee waves originating from multiple mountain ranges. In particular, wave clouds developed in regions where constructive interference locally strengthened the upward motion, whereas areas where destructive interference reduced the wave amplitude lacked cloud formation, resulting in an uneven, irregular cloud base. Nonlinear interactions further influence wave behaviour in multiple ways: latent heat release within clouds strengthens vertical motion, amplifies waves, and alters their phase, whereas excessive growth triggers convective overturning and Kelvin–Helmholtz instabilities, leading to wave breaking and significant amplitude reduction. The coexistence of interference and nonlinear effects produces localised zones of amplification and dissipation, shaping complex cloud bases and spatial wave patterns.