Sun, Wind, and Polar Rain:
The near Earth plasma environment
Thomas Ulich
Department of Physical Sciences, University of Oulu,
Linnanmaa, FIN-90570 Oulu, Finland
Abstract
Since the beginning of the satellite era in the late 1950s the
environment of the Earth, i.e., the magnetosphere, has been
extensively examined. It has been discovered that the shape of the
magnetosphere is a direct consequence of the interaction between
the solar wind and the geomagnetic field. We give an introduction
to the magnetic environment of the Earth and show how it is
stabilized by a system of currents and electric fields. We discuss
geomagnetic disturbances such as substorms. Even though many
magnetospheric processes are nowadays well understood, those
triggering the series of events leading to auroral substorms have
not been clearly identified by now.