A worldwide major disturbance of the earth's magnetic field caused by the interaction of the earth with high-speed charged particles ejected from the sun following a solar flare.
Origin
1940s.
Definition of geomagnetic storm in US English:
geomagnetic storm
noun
A worldwide major disturbance of the earth's magnetic field caused by the interaction of the earth with high-speed charged particles ejected from the sun following a solar flare.