Evolution of secondary KH instability in the prominence at time = 274.79, 291.97, and 343.49 s as shown in the red insets. The top row shows the zoomed image for the KH instability regions, represented as both vorticity ∇ × v and Rortex R, identified using the velocity magnitude in the middle row for each time. The bottom insets show the zoom region for time = 291.97 s, representing the v_y and v_x component of the velocity field at that time. Together, they signal a trail of (rising) vortex structures being formed.