Top: loop position obtained from IRIS as a function of time. The error bars correspond to the half-width of a Gaussian profile fitted to the loop cross-section at each time. The dashed lines are linear fits to each time series. Middle: loop displacement as a function of time obtained by subtracting the linear profile from the loop position time series. The red and green curves are fitted sinusoidal curves with the corresponding parameters listed. Bottom: position of individual rain blobs as distance relative to the approximate loop top x₀, as a function of time.