The ring current and the outer atmosphere

It is shown that hydromagnetic propagation will enable the earth's field at ground level to be affected with a lag of less than 1 minute by changes in electric currents far above the earth—for example, by a changing ring current with a radius a few times that of the earth. It is shown that a system of trapped high-speed charged particles, such as those in the Van Allen belts, involves electric current flow; the deciding factor is the curvature of the guiding lines of the geomagnetic field. Thus an enhancement of the Van Allen radiation belts will decrease the horizontal geomagnetic component. Such a change is observed during the main phase of a magnetic storm. A suggestion is made about the origin of trapped high-energy particles from the analysis of two large magnetic storms during the IGY.