The plasmasphere is the cold dense (few 100 to few 10000 charged particles per cubic centimetre) plasma surrounding the Earth and corotating with it. The plasmasphere is filled with plasma along magnetic field lines from the underlying sunlit ionosphere. The filling process starts at (local) sunrise and last until sunset each day, while at night the plasma flows back to the ionosphere. During geomagnetic storms the plasmasphere is eroded, the plasma on its outer shells are swept away by the increased convection in the outer magnetosphere. The outer boundary of the plasmasphere is called the plasmapause (PP).