What’s this blog all about??

BBC Theme – Frozen

First posted on 26 Jan 2012

Water is unique on earth as the only natural substance that can be found in all three states (as a gas, liquid and as ice) at the temperatures found ‘naturally’ on our planet. Water is essential for life, without it enzymes do not work and there is no liquid that can replace it. It is also known as the universal solvent, more things dissolve into water than any other liquid. 

Scientists have many theories as to how life began on earth, they vary in their technical details but one factor is always present in the equation. Water. Without water life would never have developed on earth. We owe everything to the stuff and yet we take it completely for granted, and in certain regions of the world we curse its incessant drizzling from the sky.  Thank you Yorkshire and Lancashire.

Water has remarkable hydrogen bonds – slightly stronger or weaker and we wouldn’t be here.  The Hydrogen bonds are the relatively weak bonds that form between the two Hydrogen atoms and the one Oxygen atom in liquid water and ice. They are the force that make water a magical molecule.

Without the strength of the hydrogen bonds in water there wouldn’t be so much surface tension, and without surface tension trees would not be able to take water up to their tops. Surface tension and capillary action affects a plethora of functions, it is why water forms droplets rather than forming an even film on surface. 

The frozen forms of water inspire and fascinate me. Ice, snow, hail, icebergs, glaciers and icicles. I think my enthralment with ice stems from a love of the mountains, skiing and mountain walking. But also it has quite a spiritual side to it…. The remarkable properties of ice and water make me think more deeply about religion, the idea of a creator and my deep belief in science more than anything else that I’ve ever encountered. 

Hydrogen bonds are also important in what I think of as one of the most remarkable features of water. That fact that when water freezes it expands. This is why pipes burst in the winter. It is why icebergs, and the ice cubes in your drink float.

The temperature of maximum density is 4 degrees Celsius this would change, with quite interesting consequences if the hydrogen bonds were just a little weaker – in fact just 2% weaker. Below 4 degrees Celsius water becomes less dense, and frozen water is 10% less dense than liquid water.

Most molecules contract when they freeze, when they turn from a liquid into a solid they get smaller in size. If a molecule contracts it becomes denser, because there is the same amount of stuff in a smaller space. So conversely if a molecule expands upon freezing it must become less dense.

So water expands as it solidifies. This may sound unremarkable, but it pretty much the only molecule in the world that does this.

Let’s think about the alternative. If ice was heavier (or more correctly, denser) than liquid water then lakes would freeze from the bottom up, instead of freezing first on the surface with the remaining liquid water below staying warmer than the surface.

If lakes froze from the bottom up it is pretty likely that they would never defrost.  Most of the water on the planet would remain frozen, and it is very very unlikely that life would have been kick started from the primordial soup.

Expansion upon freezing occurs because water crystallises into an open hexagonal form. This lattice has more space within it than liquid water. Hexagonal forms of ice are the most common, but scientists have identified at least 13 other crystalline forms of ice. 

Ice and water are also physically powerful, this wasn’t fully appreciated until someone worked out the riddle of glaciation and ice ages. When people began to notice that there were rocks in places that they shouldn’t be in and gorges, scratches and marks carved in solid rock it took a long time for anyone to realise that it wasn’t a flood that moved the rocks or a passing cart that scratched the rock (to paraphrase Bill Bryson), it was in fact the result of glaciation.

This was deemed preposterous by the scientific community of the time, but in fact local people had known about the power of ice for many years.

In Switzerland they knew that the glaciers retreated and extended to different points in the valleys and they could see the results. Scientists from England, especially ones who didn’t like travelling found this idea ridiculous. 

It took until someone discovered Greenland, to show that large sheets of ice could cover entire continents, tearing its way through granite, picking up and moving boulders and leaving a trail of moraine. The science of glaciology was born and we began to learn how ice shaped the earth.

I never understood my love of the mountains until recently, my mother told me a story about when I was younger. The story goes that my parents took me to Germany on holiday and I’d saw my first mountain, I can’t imagine I was much older that 4 or 5.

I was brought up in Norfolk (the flat land!) so this was quite a big change. Apparently I got out of the car and saw the mountain, pointed to the top and said, ‘can we go there, can we go there, can we go there’, and pretty much set off up the hill.

My mum was surprised and I rarely partook in movement. For example, forcing her to take me to school in the push chair until I was far too old and sitting contently wherever she put me.  Later on in life I discovered winter sports and fell back in love with mountains, ice and snow. 

Along with all its recreational and aesthetic wonders frozen water really is remarkable.

Actually, it is water that is remarkable, but frozen water is maybe more fun? 

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