Large‐scale inhomogeneities in the solar wind of solar origin

The most notable contributions to our understanding of large‐scale inhomogeneities in the solar wind have come from the following developments: the creation of realistic nonlinear models of solar wind stream interactions and evolution with increasing heliocentric distance; the careful observational study of solar wind stream structure, particularly that work that delineated the role of stream interactions and evolution in producing solar wind variability; the coming of age of radio scintillation measurements which have allowed the routine observation of stream flow far from the ecliptic; the discovery of coronal holes and their identification as the probable source of many recurrent solar wind streams; the development of nonspherically symmetric models of the coronal expansion which included effects of the coronal magnetic field; the recognition that alpha particle enhancements often identify material ejected from the sun at the time of large solar flares; the application of the Culgoora spectroheliograph to the study of type 2 and 4 radio bursts; the advent of low‐frequency observations of radio bursts from the sun; and the observation and analysis of numerous mass ejections from the sun with both ground‐based and satellite coronagraphs. The present report concentrates on the author's interpretation of the most outstanding developments in these and other areas. A comprehensive bibliography of all U.S. work and some foreign work in the field published or in press from January 1971 through November 1974 is attempted at the end of the article.