Population of HI high-velocity clouds from the surveys of McClure-Griffiths et al. (2013) and Di Teodoro et al. (2018), taken with the ATCA and the GBT. Left: galactic latitude-longitude map. The data-points show the positions of the clouds and are color-coded by their v_LSR. The white mask shows the region surveyed by the ATCA and the GBT. Right: HI cloud latitudes as a function of their velocities. The kinematic pattern shows a signature of acceleration (see main text and Lockman et al. 2020). The points are color-coded by the cloud mass and the full 1D mass distribution is shown in the inset panel.