The lower regions (90–120 km) of the ionosphere, which reflect radio waves, allowing their reception around the surface of the Earth. The E-layer approaches the Earth by day and recedes from it at night.
Electronics and Electrical Engineering
Seeionosphere.
Geology and Earth Sciences
1. The outer core of the Earth between about 2886 km and 5156 km depth, mainly defined on seismic velocities.
2. The ionospheric layer at about 100 km height from which 3.5 MHz radio waves are strongly reflected.