This is an image of a fluid flow transitioning from laminar to turbulent flow across a flat plate. This phenomenon occurs above a certain Reynolds number at the interface of a fluid and a solid boundary and is affected by the flow parameters, fluid properties, and surface roughness. I appreciate this photo scientifically because it allows us to visualize the effect of friction on a flow, causing instabilities that grow quickly into disorder. The transition process can be broken down into clear steps that can be seen in the photo. The flow begins as a smooth laminar flow when small two-dimensional waves appear. These waves then roll up into small vortices after which small turbulent spots begin to develop before we see fully turbulent flow on the far right. Artistically, this photo is beautiful as it shows clean and smooth lines slowly developing into chaos. This seems like the yin and yang of fluid dynamics, showing the extreme opposites of order and predictability with chaotic randomness.
Original Author: Henri Werlé in his paper Transition and separation: Visualizations in the ONERA water tunnel (1980). Also appears in An Album of Fluid Motion by Milton Van Dyke.