ELECTROMAGNETIC WAVES????

Sky Wave Propagation

The radio waves upto 30 MHz which are reflected back to the earth by ionosphere are called sky waves. The mode of propagation of sky waves is known as sky wave propagation. The ionosphere has a large number of ions or charged particles whose concentration varies with height. Electro magnetic waves of frequencies higher than 30 MHz penetrate the ionosphere and are lost. The bending or reflection of EMW is similar to total internal reflection.