Crazy Whistlers

Created by Jobro
A Whistler is a very low frequency electromagnetic (radio) wave generated by lightning. Frequencies of whistlers are 1 to 30 kHz, with maximum usually at 3 to 5 kHz. Although they are electromagnetic waves, they occur at audio frequencies, and can be converted to audio using a suitable receiver. They are produced by lightning strikes (mostly intracloud and return-path) where the impulse travels away from the earth and returns to the earth traveling along magnetic field lines. They undergo dispersion of several thousand kHz due to the slower velocity of the lower frequencies through the ionosphere. Thus they are perceived as a descending tone which can last for a few seconds. The study of whistlers allows categorization into Pure Note Whistlers, Diffuse, 2-hop, and Echo Train types.