Corotating Interaction Regions

A Corotating Interaction Region (CIR) is the result of the interaction of fast solar wind with slower solar wind ahead. CIRs have a very large three-dimensional ex­ tent and are the dominant large-scale structure in the heliosphere on the declining and minimum phase of the solar activity cycle. Until recently, however, CIRs could only be observed close to the ecliptic plane, and their three-dimens...