As the atmospheric conditions worsen, ionization begins near high-voltage electrical lines. This means that the air is being electrically charged, which can alter the behavior of nearby electrical systems. The ionization is detectable by radio emissions, suggesting a disturbance in the electromagnetic field.
The radio signal would sound like irregular bursts of static, chirps, or popcorn-like crackling, depending on the intensity and nature of the ionization.
Short bursts of noise whose frequency rapidly sweeps up or down — much like a bird’s chirp or a bat’s sonar call.
In technical language, this is a frequency-modulated impulsive emission.