The Traces of a Passing Fisher
Hajoon Pong
Award: Top 100
School: horace mann school
Teacher: dr e. jane wesely
Category: Natural
Photo #20854
The Traces of a Passing Fisher
Bali is known to be a world-class location for the average tourist with beautiful beaches, luxurious hotels, and stunning surfers. But there exists a different side of Bali, with beaches littered with plastic and the stench of rotting fish. One such place is Jimbaran Beach, where I took a photo of a local fisherman attempting to catch fish in the early morning.
His movement on the paddleboard creates a phenomenon known as a wake. As his paddleboard moves, it creates disturbances that push water outwards as energy is transferred into the surface of the water. What comes out are many outward-moving circular waves that begin to overlap and interfere with each other, creating amplified and diminished regions through constructive and destructive interference. What is produced is a visible wake.
Wakes can be created by a variety of sources, from boats to ducks to even a swimmer! Interestingly, they almost always create a V-shaped structure known as the Kelvin wake pattern. This happens due to both the source outspeeding the wave propagation and wave dispersion in water, where the wave speed is variable depending on the wavelength. As the paddleboard moves, its longer, faster waves spread farther outward and help define the outer V, while shorter, slower ripples stay closer to its path. In the photo, there are clear, long outermost waves, embedded by a smaller V-shape created by the aggregation of smaller and slower waves. Ultimately, this photo shows a prevalent and deceptively unassuming phenomenon in physics.
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