Lee waves, commonly known as mountain waves, are generated during wind flow over obstacles like mountains, ridges and valleys. These waves are stationary in nature and their length scales are comparable to the scale of the obstacle. Lee waves generated by large mountains often impact on the formation of wave clouds and affect local climate and aviation safety. Waves can steepen enough to overturn and break. The project will involve both laboratory and numerical experiments designed to explore nonlinear breaking of lee waves produced by a model ridge. The mechanical energy transformations, production of turbulence, dissipation and irreversible mixing will be examined in order to understand these waves and the resulting turbulent mixing.