Nonequilibrium systems show spatio-temporal dynamics of self-organization, pattern formation, phase change, etc. Phenomenological aspects of physical principles are explained based on growing fluctuation due to system instabilities. Microscopic fluctuation grows rapidly up to the macroscopic scale which forms visible spatial structures. Such structures are called dissipative structures. Dissipative structures are maintained by the difference of chemical potential, that is, temperature or density difference, etc. In this conditions, convection due to gravity often couples with nonequilibrium dynamics and modifies the physics observed. According to this considerations, physical principles of gravity effects on nonequilibrium systems, such as BZ reactions, nucleation, and phase change are summarized.
