Raindrops Should Not Be Possible

Raindrops Should Not Be Possible

A lot of physics sits inside one tiny raindrop: cohesion, adhesion, and air resistance, to name a few. Of course raindrops exist, but the mathematics behind them doesn't quite line up. Surfaces require more free energy to make than volumes, which is why small water droplets pose a problem. If a water droplet is below a certain size, then making it bigger requires more surface energy than is released from volume energy, which means it would take energy for the droplet to grow—but it doesn't, it shrinks. To help understand this, think about small decimal numbers: squaring and cubing them actually makes them smaller, not larger.

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Key Facts In This Video

  • 1

    Falling raindrops are more often shaped like jellyfish than teardrops. (0:05)

  • 2

    Surfaces require more free energy to make than volumes. (0:41)

  • 3

    If a water droplet is below a certain size, then making it bigger requires more surface energy than is released from volume energy. (1:24)

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