Effects of Solar Activity on the Ionosphere and Radio Communications

The relationships of solar activity on the ionosphere and radio communications may be roughly classified as follows: (1) There are occasional solar flares or outbursts of ultraviolet light which instantaneously produce radio fade-outs of short duration. (2) Occasionally solar streams of particles sweep across the earth's orbit producing magnetic storms and auroral displays. The associated ionospheric disturbances may seriously affect radio communication for several days although the effects are more pronounced in polar regions. (3) The general change of solar ionizing wave radiation in the course of the sunspot cycle governs the average intensity of ionization in the ionosphere. This trend is an important factor governing selection of operating frequencies for radio communication.