Hybrid solar wind velocity profiles for different values of the free parameters r_s, calculated for an in situ solar wind speed of 600 km s⁻¹ (colored lines). Observations of solar wind outflow velocity close to the Sun, based on the Doppler dimming method are shown as lines with symbols. The velocity profile with constant speed is displayed by the horizontal dotted line. The profile output by the model of Hu & Habbal (1999) is also overploted, for comparison.