An antibubble is a droplet of water surrounded by a thin film of air, as opposed to an air bubble, which is a sphere of air surrounded by a thin film of water. Antibubbles are formed when water drops or flows turbulently into water.

Antibubbles are a very common but widely unrecognised phenomenon, in part because of their resemblance to air bubbles, and in part because of their transient nature.

The behavior of antibubbles differs from that of air bubbles in three primary ways, and provides a ready means of identification:

  • Antibubbles are not held in place by surface tension, and move rapidly across the surface of the water. They can also be seen to ricochet off the sides of a container in a manner similar to that of billiard balls.
  • Antibubbles are short-lived. An air bubble with a soap skin may last a minute or two. Antibubbles have lifetimes of a few seconds or less.
  • Antibubbles refract light in a different manner than air bubbles. Because they are water droplets, light entering them is refracted back toward its source in the same manner as sunlight is refracted through raindrops to produce a rainbow. Because of this refraction, antibubbles have a bright appearance.

    Antibubbles are easily created by allowing a tap to drip into a container of water to which a drop or two of soap has been added. The soap reduces the water's surface tension and allows the skin of air surrounding the droplet to remain in place for more than just a fraction of a second.

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