Amplitude distributions of all impacts (grey bars) with morphological types A and B measured by the y-antenna, impacts measured only when the spacecraft moved against the ISD inflow direction during February, March, and April (shown with blue filled bars outlined in white), and impacts measured only when the spacecraft moved with the ISD inflow direction during August, September, and October (shown with red filled bars outlined in black). The distribution of all impacts has been scaled by a factor of 0.5 to tighten the histogram’s vertical axis. The vertical dashed green lines indicate every 20^th percentile of the signal amplitude; the weakest and the strongest 20% of all impact signals were selected when generating Fig. 7.