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The Shape of a Water Droplet
Why some droplets are spherical while the others are not
A dripping faucet in a kitchen is an ordinary-looking everyday thing. A thread of water emerges from the faucet and forms a droplet. Sometimes, the thread is big enough that it breaks into a series of droplets. The formation of droplets from a jet/thread of water is very rich in physics and absolutely beautiful (I encourage you to look at high-speed footage of similar phenomena here). These droplets are of different sizes and shapes. They are not always spherical (Fig. 1).
Raindrops form in clouds. As they fall, they coalesce and form bigger droplets. These bigger droplets then disintegrate into smaller droplets (anatomy of a raindrop). According to Villermaux and Bossa, the raindrop deforms/flattens before it starts disintegrating, as seen in this beautiful movie. Careful observation shows that, after the breakup event, the smaller child droplets are almost spherical, whereas the larger ones oscillate/deform. It is likely that these larger child droplets do not undergo further breakup and they keep oscillating/deforming. They may even achieve an equilibrium shape that looks like a bun, similar to the shape of the droplet from this beautiful artwork by Alistair McClymont (where the water droplet is suspended using a vertical wind tunnel and it has an equilibrium shape that…
