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![[Post New]](/templates/default/images/icon_minipost_new.gif) 25 Mar 2008 01:30:55 IST
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Just somthing more to add on: Solar radiation, acting on the different compositions of the atmosphere with height, generates layers of ionization:
D layer,Elayer,Es layer,F layer D layer is 50-90 km abov earth's surface here ionization is due to Lyman series, mainly oxidising NO Recombination is high in the D layer, thus the net ionization effect is very low and as a result high-frequency (HF) radio waves aren't reflected by the D layer. The frequency of collision between electrons and other particles in this region during the day is about 10 million collisions per second.
E layer is the middle layer, 90 km to 120 km above the surface of the Earth. Ionization is due to soft X-ray (1-10 nm) and far ultraviolet (UV) solar radiation ionization of molecular (O2). This layer can only reflect radio waves having frequencies less than about 10 MHz. It has a negative effect on frequencies above 10 MHz due to its partial absorption of these waves.
Es layer or sporadic E-layer. Sporadic e propogation is characterized by small clouds of intense ionization, which can support radio wave reflections from 25 ? 225 MHz.
and i hv already told abt F layer
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