Distribution of densities (left) and temperatures (right) of plasma parcels versus their velocities at 1 AU, as derived by Eq. (18) for an HSS with a diameter of 22°. Each line represents plasma parcels originating from a different longitudinal slice through the HSS, resulting in a different radial expansion. The numbers give the latitudinal displacement of the slice to the center of the HSS; slices > 5° lie entirely within the northern boundary region. For comparison, the dashed diagonal line shows the solution for the case in which the radial expansion of plasma parcels is neglected.