Because of the inertia of the neutral air, a few hours are required to set up disturbance winds. Once set up, they can persist for several hours. Thus low-latitude electric-field disturbances associated with the disturbance winds tend to be more persistent than those associated with changes in direct penetration from the polar cap and with changes in the Region-2 currents. Different aspects of the dynamo influences of disturbance winds have been given different names.