Equatorial ionospheric electric fields are also affected by thermospheric winds in the dynamo region, which lies primarily between 100 km and 200 km at day and in the lower F region at night. The winds are driven by day-night differences in solar heating, by upward propagating atmospheric tides, by collisional interaction with rapidly convecting ions in the presence of strong high-latitude electric fields, and by Joule heating associated with the strong
high-latitude electric currents. The latter two sources are highly variable, and depend on the level of geomagnetic activity. They produce thermospheric disturbance winds, which affect the global ionospheric dynamo