On wave turbulence in MHD

We describe the fundamental differences between weak (wave) turbulence in i ncompressible and weakly compressible MHD at the level of three-wave intera ctions. The main difference is in the structure of the resonant manifolds a nd the mechanisms of redistribution of spectral densities along the applied magnetic field B-0. Similar to pure acoustic waves, a three-wave resonance between collinear wavevectors is observed but, in addition, we also have a resonance through tilted planes and spheres. The properties of resonances and their consequences for the asymptotics are also discussed.