( iv) Ionosphere This region extends from 80 km to 400 km.
In ionosphere the electron density is very large in a region beyond 110 km from earth’ s surface which extends vertically for a few kilometer.
This layer is called Kennelly Heaviside layer.
In ionosphere a layer having large electron density is found at height 250 km from earth’ s surface, called Appleton layer.
There are four main layers in earth’ s atmosphere having high density of electrons and positive ions, produced due to ionisation by the high energy particles coming from sun. star or cosmos. These layers play their effective role in space communication. These layers are D, E, F 1 and F 2.
( i) D-layer is at a virtual height of 65 km from surface of earth and having electron density = 10 9 m-3
( ii) E-layer is at a virtual height of 100 km, from the surface of earth, having electron density = 2 * 10 11 m-3
( iii) F 1-layer is at a virtual height of 180 km from the surface of earth, having electron density = 3 * 10 11 m-3
( iv) F 2 – layer is at a vertical height of about 300 km in night time and about 250 to 400 km in day time. The
electron density of this layer is = 8 * 10 11 m-3