Atmospheric Interference in Radio Reception

the interference with radio reception resulting from electrical processes that take place continually in the earth’s atmosphere. Every irregular change (discharges and such) in atmospheric electricity causes electromagnetic waves of all possible wavelengths to be radiated which act on the antennas of radio receivers, producing at the output noise and crackles (in a loudspeaker), streaks, dashes (on a kinescope), and so on. The level of the interference picked up by an antenna depends on the distance and conditions for radio wave propagation (at a given time of day and year) between the point of the waves’ origin and the receiver location. Atmospheric interference is most disturbing at the long and medium wavelengths of the radio broadcasting range; upon shifting to the short wavelengths, the interference is sharply diminished. Exceptionally strong interference is created by lightning discharges. In the USSR the most intense thunderstorm region is the southeastern part of the country. In order to attenuate atmospheric interference, directional antennas (when the direction of the desired radio station differs from that of the interference source), as well as special radio receiver circuitry, are used.