9. The Sound of Red Lightning
Although red lightning is mostly recognised for its visual display, new studies have shown that these episodes are also linked with unusual audio disturbances. Unlike the distinctive crack and rumble of ordinary lightning, the sounds generated by red lightning are subdued and generally undetectable to ground-based viewers.
Red lightning occurrences have been found by scientists to produce low-frequency sound waves sometimes referred to as infrasound. Though they have frequencies below the lower limit of human hearing (usually approximately 20 Hz), these sound waves can be heard with the aid of specialist equipment. The fast heating and expansion of air in the high atmosphere during the electrical discharge is hypothesised as the source of the infrasound generated by red lightning.
Fascinatingly, the infrasound signals of red lightning episodes can travel great distances throughout the atmosphere, occasionally spreading hundreds or perhaps thousands of km. This feature makes infrasound detection a useful instrument for red lightning research, therefore augmenting visual and electromagnetic data.
Furthermore noted by researchers are unique auditory patterns linked to various kinds of red lightning. For instance, although elves emit simpler, more explosive signals, sprite discharges sometimes produce complicated infrasound signatures with several frequency components.
Red lightning acoustics research offers not only scientific value but also pragmatic uses. By means of infrasound monitoring, red lightning episodes visually hidden by clouds or occurring beyond the horizon can be detected and characterised, hence improving our capacity to investigate these elusive events.