Floating water globules (science trivia thing)

Drops of water can float on the surface of a body of water.

Floating water globules are sometimes mistaken for bubbles on the surface of water, but they're not bubbles. They are globules of water floating for a while, eventually sinking.

If you're not sure about this and want to see it, try flipping a spoon across the top of your coffee or tea, using a slight lifting motion. Or else, let tap water drip into a clean container for a little while, or watch rain dripping from an overloaded gutter onto a puddle on a sidewalk. The floaters are conspicuously different from bubbles because they dart across the surface, whereas bubbles slowly meander.

People who row a boat on a calm lake are likely to recognize the phenomenon. When rowing, the globules spreading off the oars can be quite large and easily visible.

Why does this happen?

Water molecules are asymmetrical. Two hydrogen atoms and one oxygen. H2O molecules are asymmetrical. Their electrical potential is slightly opposite at each end. A group of water molecules at the surface of a body of water will align with a negative charge facing outwards.

Floating globules of water ride an electrostatic cushion. They tend to get smaller in stages and then sink. At the bottom of the globule there may be contact with the surface of the water they ride upon, or the prick of a speck of dust opens the globule at the bottom. The release of a small jet of water, directly downwards, can lift the little globule back up so it reseals. It's now smaller, yet it floats a little while longer. It's even possible to squirt two streams of water droplets from opposite directions, towards a central point on a water surface, and end up creating water globules that consolidate into a larger globule.

The distance between a floating water globule and the surface of the water it rides upon is so tiny that it causes interference to any light waves passing through, so it's possible to see colorful Newton's rings if a light is shining through a large floating water globule from the top.

Update: Since writing this, someone was kind enough to draw my attention to the idea that "non-polar fluids" may also exhibit the same phenomenon, floating globules, apparently due to simple surface tension of a fluid.


A nice picture here:

Water globules

Video here:

Water Droplet Bouncing on a Superhydrophobic Carbon Nanotube Array

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