Ice is far more important than it appears to be. "Ice is responsible for the existence of life on Earth.
It is quite a unique substance because solids are generally denser than their liquid counterparts. So, they mostly sink if placed in their liquid form but ice, despite being a solid form of water, floats on it.
That’s because ice is less dense than water. At molecular level, you will see these randomly moving H2O molecules in water,
which, if cooled below 0 degrees, convert into ice and get locked in this beautiful cage-like structure.
To understand how this cage forms, you can watch the supercooling video: • Secret to Freezing Wat...
During cooling, as the temperature falls, the randomly moving H2O molecules slow down and come closer. As a result, the density of water increases. However, this happens only up to 4 degrees Celsius. If cooled below 4 degrees, it will start to expand. That’s because as the temperature dives below 4 degrees, water is nearing its freezing point, so its molecules try to arrange themselves in that cage-like manner. While doing so, they move apart, and it expands. Hence, water below 4 degrees is less dense and tends to float over warmer water.
At 0 degrees and below, these molecules successfully form cage-like structures and water changes to ice. Ice molecules have large gaps between the cages, which makes it even less dense than cold water and ice floats over it.
While most liquids contract and become denser, water expands and becomes less dense, if cooled below 4 degrees. This is what we call the anomalous expansion of water or anomalous behaviour of water.
But what ice has to do with life on Earth?
At sub-zero temperatures, you might think that a lake should completely freeze. If that happens, fish and other aquatic life will just freeze to death.
But that doesn’t happen!
Because as the temperature of water starts to fall
below 4 degrees, its anomalous behaviour kicks in
causing less dense colder water to float on the
surface where it further cools down to form ice.
Ice being less dense, floats and covers the water body like a blanket. It’s also a poor conductor of heat, so a thick layer of it insulates the
underlying water from the frigid atmosphere, preventing it from freezing. So, the water underneath remains liquid and aquatic creatures happily survive beneath this icy layer.
That's how ice is responsible for the existence of aquatic life.
But not just aquatic, polar ice caps at the north and south poles are nothing but massive ice blocks floating over the water. They reflect most of the solar radiation into space and regulate
Earth's temperature and help in reducing global warming. In their absence, Earth will become so hot that life won't be possible on it.
That’s how life on Earth owes a great thanks to floating ice.
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19 июл 2022
