Amplitude distributions of all impacts (grey) with morphological types C and D measured by the y-antenna, impacts measured only when the spacecraft moved against the ISD inflow direction (February to April; blue and white), and impacts measured only when the spacecraft moved with the ISD inflow direction (August to October; red and black). The distribution of all impacts has been scaled by a factor of 0.5 to tighten the histogram’s vertical axis (see Fig. 8.)