Photo Credit: NASA Langley Research Center
This photo depicts the wingtip vortices of an agricultural airplane. The airflow is depicted using colored smoke. This phenomenon occurs when air “leaks” around the wingtips from the high to low-pressure sides. This causes a small downward component of velocity in the neighborhood of the wing itself, which causes the circulatory motion around the wingtips.
I like this photo because it depicts this phenomenon in an interesting, artistic way. The use of the opposing colors (red and blue) highlights the vortex coming from the left wing of the airplane. There is enough space in the photo to encapsulate the entire vortex along with undisturbed smoke, showing the full effect of this vortex phenomenon.