Every school child knows that water is 75% of the Earth’s surface, 75% of our bodies, 75% of a good, balanced meal, and 75% of just about anything that you can make up a bogus and totally random statistic about. Water has many peculiar properties that seperates it from other types of materials. This article is Part 1 of a series looking at the effects of Earth’s peculiar liquid: water.

Everyone knows that ice-cubes float. But did you know that the peculiar property of water that, unlike the solid of any other material, makes it less dense (and therefore “floaty”) when it is frozen, actually makes life on Earth possible?

The molecules of most chemicals bunch up as they get colder, reducing the volume and increasing the density of the mass as it approaches freezing. The crystaline structure of water, on the other hand, becomes more rigid, with the individual molecules moving into alignment and actually expanding 9% as it freezes.

So why do I say that this makes life possible? Imagine an Earth where every winter, water at the surface froze as it lost heat to the cooling atmosphere, and then sunk. The sunken ice at the bottom of all the water bodies would never have enough time to thaw before the end of summer heat, which means that the next winter’s ice would sink down to stack on the ice of the summer before, eventually locking the world’s water in a never-melting block of ice.

Floating ice, on the other, other hand, insulates the water below it, keeping it from freezing through the winter, and allowing aquatic organisms to survive the cold season. So there you have it: ice floats = life on Earth.

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