Two magnetic hole examples from Karlsson et al. (2015). Left panel: cluster 3 interval from 11 March 2003, showing a unipolar magnetic hole in the solar wind with anti-correlated density variation. Right panel: cluster 3 interval from 10 January 2003, showing a bipolar magnetic hole in the terrestrial magnetosheath, co-located with a current sheet and featuring a shifted density response. From top to bottom panels: (1) magnetic field in geocentric solar magnetospheric (GSM) coordinates, (2) modulus of the magnetic field, (3) electron density derived from the Electric Fields and Waves (EFW) instrument, (4) ion temperatures in magnetic field parallel (blue) and perpendicular (black) directions, and (5) ion velocity in GSM.