A new theory of magnetic storms

6—The phenomena accompanying the advance of a solar ionized stream into the Earth's field.6.1—A stream of particles emitted nearly radially from an active area A on the Sun will have a curved form, on account of the Sun's rotation. The stream will lag slightly behind the solar radius through the emitting area A though each particle of the stream will move almost rectilinearly, approximately along the solar radius through the position of A at the instant of emitting that particle. The rate at which the lateral surface of the stream will approach the Earth, overtaking it in its orbital motion, depends only on the Sun's known angular velocity; the point of intersection of the Earth's orbit with the lateral surface of the stream moves relative to the Earth with a velocity of about 400 km/sec, thus traversing a distance equal to one Earth-radius in about 18 seconds. If undisturbed by the Earth's field the stream would sweep across the Earth in about 35 seconds.