Left: maximum in situ measured SW speed vs. CH area. Right: absolute difference between the fitted value and the measurements, with a black dashed line indicating zero difference. The blue circles denote data points related to Earth, the red triangles denote data points related to Mars. The respective colors are also used for the correlation coefficient values given in the legend. The error of the CH area scales with the uncertainty of extraction; for instance, CHs that lie close to the solar limb have a larger error. The error of the measured maximum bulk velocity was set to ±5 km s⁻¹.