Order out of chaos: Shifting paradigm of convective turbulence.

Turbulence is ever produced in low-viscosity/large-scale fluid flows by velocity shears and, in unstable stratification, by buoyancy forces. It is commonly believed that both mechanisms produce eddies breaking into smaller ones and making direct cascade of turbulent energy from large to small scales towards viscous dissipation. Conventional theory based on this vision yields plausible picture of vertical mixing and remains in use more than half a century in spite of increasing evidence of fallacy of its other predictions. This paper discloses that buoyancy produces buoyant plumes, merging into larger ones and making inverse cascade towards their newly revealed conversion into self-organized regular motions. Herein, shears produce usual eddies making direct cascade. The new paradigm is demonstrated and proved experimentally; so, the paper launches main revision of current theory of unstably stratified turbulence.