At various speeds, as a window is lowered, passengers could experience a feeling of dizziness or disorientation associated with a “pulsing” sensation of the air inside the vehicle.
This issue, known as buffeting, can occur during both high and low speeds, and is often associated with a change in air pressure inside the vehicles cabin.
There are multiple causes associated with this effect, but it is mainly attributed to the precision streamlining of modern vehicle designs. Many vehicles are designed in conjunction with air flow tests performed under laboratory conditions, inside of a “wind tunnel”, which tests the effects of physical vehicle-body design, against airflow and aerodynamics, as it travels at different speeds.
The “buffeting” effect is caused by a sudden change in the aerodynamics of the vehicle, caused by the lowering of a window, which changes how the air is flowing over the surface of the vehicle. The effect can be corrected by raising or closing the offending window to correct the airflow. This effect can also be attributed, to a lesser degree, to the rapid exchange of hotter air inside the vehicle cabin, with the colder outside air, creating a vacuum effect.