streaming movement of charged particles in the ionosphere. The term is limited by some to those flow patterns that contain a significant proportion of neutral gases, but highly concentrated, laterally limited, electric currents are also called electrojets. The latter circulate within the ionosphere at heights of 80 to 100 km (50 to 60 miles) and complete their circuits in low latitudes and across the polar caps. They are associated with auroras and other magnetic disturbances. See aurora.