Microstructure of the solar wind

In this review microstructure is understood to summarize the dynamical properties of the solar wind that enter the fluid equations, usually employed to describe the overall flow, only in one or the other averaged form. Thus, first a description of the kinetic picture of the solar wind is given; it mainly involves the structure of the particle distributions in velocity space and associated instabilities. Waves and discontinuities are discussed next. Two selected examples are mentioned where the effects of waves and discontinuities play a role. Specific physical properties of the interplanetary magnetic irregularity spectrum and its relevance for cosmic ray propagation are discussed at the end.