( 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