Static is a term for a disturbance in a radio or television receiver, usually caused by atmospheric electricity. Static may take the form of crackling and grating noises heard over the radio or television. It may also take the form of white or black spots seen on a television picture.
Water droplets and dust particles in the air often carry an electric charge. Any motion of electric charges results in radiation at some frequency. If this radiation has a frequency within the radio or television broadcast bands, it will be heard or seen as static.
Ordinarily, the movement of charged particles in the air produces static in the form of a weak, hissing, background noise. However, severe disturbances to the atmosphere, such as lightning, earthquakes, tornadoes, and volcanoes, make the particles move more rapidly and the air vibrate violently. These disturbances thus cause sudden crashes, pops, and other noises. Certain electric motors and electric sparks from machinery also produce static.
