The ionosphere is the ionized part of Earth’s upper atmosphere, from about 48 km (30 mi) to 965 km (600 mi) altitude
There are three main regions of the ionosphere: the D layer, the E layer, and the F layer. These regions do not have sharp boundaries, and the altitudes at which they occur vary during the course of a day and from season to season. The D region is the lowest, starting about 60 or 70 km (37 or 43 miles) above the ground and extending upward to about 90 km (56 miles). Next higher is the E region, starting at about 90 or 100 km (56 or 62 miles) up and extending to 120 or 150 km (75 or 93 miles). Finally, the uppermost part of the ionosphere, the F region, starts about 150 km (93 miles) and extends far upward, sometimes as high as 500 km (311 miles) above the surface of our home planet.