Streams in solar wind formed by higher speed solar wind originating from coronal holes. Higher speed streams are less tightly wound in the Parker spiral compared to slower ones, and at various distanc
es the faster solar wind overtakes the slower wind ahead of it.
A feature of the solar wind having velocities exceeding approximately 600 km/s (about double average solar wind values). High-speed streams that originate in coronal holes are less dense than those or
iginating in the average solar wind.
A population of neutral or partly ionized gas clouds in the Galactic halo which are seen as high-altitude structures in the atomic hydrogen 21 cm emission at high radial velocities (v_LSR > 100 km/sec
). They have substantial neutral column densities (> 10^19 cm^-2) and their metallicities range from 0.1 to about 1.0 times solar. The distances to the majority of them remain unknown. They may represent the continuing infall of matter onto the Local Group.