A
geomagnetic storm is a temporary disturbance of the
Earth's
magnetosphere caused by a
solar wind shock wave and/or cloud of magnetic field that interacts with the
Earth's magnetic field. The increase in the solar wind pressure initially compresses the magnetosphere. The solar wind's magnetic field interacts with the Earth’s magnetic field and transfers an increased energy into the magnetosphere. Both interactions cause an increase in plasma movement through the magnetosphere (driven by increased electric fields inside the magnetosphere) and an increase in electric current in the magnetosphere and
ionosphere.