Among the more exotic proposed explanations for the Hum is the interaction between the jet stream — the powerful, high-altitude atmospheric currents that encircle the globe — and the Earth's surface. When the jet stream interacts with mountain ranges, large buildings, or other topographic features, it can generate infrasonic pressure waves at frequencies below 20 Hz, which are below the normal threshold of human hearing but can be perceived by sensitive individuals as a low-frequency vibration or pressure sensation. The jet stream hypothesis was proposed in the 1970s during the first investigations of the Bristol Hum and has been periodically revisited. It could explain why Hum reports tend to be more common in certain geographic regions (areas beneath the jet stream's typical path), why the sound varies in intensity over time (as the jet stream shifts position seasonally), and why it is more noticeable at night (when ambient noise drops and atmospheric conditions stabilize).
However, the hypothesis struggles to explain the extreme geographic specificity of some Hum hotspots — the jet stream covers vast areas, yet Hum reports tend to cluster in specific towns or neighborhoods.