Aeolian

Every wire here is tuned to the same pitch. The harp still changes note, because the wind is not choosing a string. It is choosing a harmonic.

Air moving past a wire sheds a vortex street, and the street has a frequency: the Strouhal relation ties it to the wind speed and to the thickness of the wire. When that frequency wanders close to one of the wire’s own modes, the shedding stops tracking the wind and locks onto the wire instead, holding there across a whole band of wind speeds. That is when a wire sings. You can see which harmonic has taken hold by counting the bellies in the blur, and you can hear that it is the same number, because the picture and the sound are read from one solved state rather than matched to each other.

The wires are solved. The wind is not. The vortex street is entered through measured correlations rather than computed from the flow, so this is an honest real-time model of a wind harp and not a fluid simulation. Thicker wires shed slower, so at any given moment the rank is usually holding several different harmonics at once.