Friday, 3 December 2010

Celebrating Ice


I see that, just like last year, a bit of water in its solid form on the ground has, well, ground things to a halt again - apparently it's making even more news than the coming Royal Wedding. It's not stopping the students demonstrating in the open air, though! Oh and I hear we're out of grit? Come and sweep some off Haverfordwest's streets, there's so much I mistook a huge puddle of it for the results of an over-enthusiastic night out . . .

All right, sarcasm over (head over here for more from me if you like that sort of thing).

I have to say a personal thank you to the ice that froze on the inside of my car's windscreen, because it finally cleaned it. I'd dried off some condensation with a cloth bag weeks before, and it had been mucky ever since - despite umpteen cleans with tissue paper, towel, ice scraper, glass cleaner, and you name it - which made driving in the sunset a particular eye-watering nightmare. But every bit of that dirt fell off with the ice!

But look what came out of our bird bath a few days ago . . .



The leaves are actually less obvious to the naked eye than to my mobile's not-very-good camera. I think the ice actually expanded away from them, but retained their veiny patterns, so that it looked like a laser cutting into a piece of glass. Sadly, it's melting now . . .


I noticed that when I arrived home in the rain . . .

Off the topic of ice for a moment, I had one of those headache-inducing-ly annoying days at work today. It was supposed to be my day off, but of course certain people (who don't usually work in my office) decided to summon in me, and someone else who's disabled and doesn't come in on a Friday, all the same for our delightful monthly meeting. What happens in these is that we provide a lot of tea and biscuits, shove all our stuff off our information table for our guests, get yelled at for not doing it fast enough and generally criticised because our desks aren't empty (doh . . . believe it or not, we do do paperwork in my office), put the table somewhere stupid, arrange chairs for those who demand to be waited on hand and foot, apologise when the phone rings because somebody actually needs us, and take minutes while the same two people (neither of whom work at our office) go on and on and on about how sleepless they are about our future and how many idiotic irrelevant things they demand we must do instead of look after the people we're supposed to be serving. You get the picture. Pretty typical office meeting, I should imagine. To be fair, it isn't half as dishonest, unprincipled, bullying, or generally stressful and soul-destroying as the meetings I sat in on when I was teaching . . .

Anyway, today the person who generally takes the minutes and provides the records in my department hadn't turned up. So this task fell to me, as did taking the prolonged public kicking for not knowing the things this person knows, who has been here 15 years longer than me, and because somebody didn't know something that I thought they knew and that wasn't part of my plans so not my job to tell them . . . Again, you get the picture. I'll shut up now.

I then had an icy walk to the car and shopping to do, and my head was pounding. On the roads leading away from the town I work in are signs to one of our local beaches. They point right, while my home lies left (roughly speaking).

So today I thought . . . I will follow those signs.

As soon as I'd parked the car and got out to hear those waves between the still, silent cliffs, I felt better. The wind was painful around my un-scarfed face, it got in under my coat, and the clouds were dark; but the sea was a surprisingly bright blue-green.


This is Broad Haven according to the holiday websites . . .


This is it earlier today . . .


. . . yep . . . lots of water had frozen right there on the stones and sand. I walked on ice puddles which made wonderful noises but did not snap, merely created bubbles and pushed the sand around! (I'm actually really cheesed off - you see that blurry bit on the bottom right? That was an amazing ice puddle in which stones were nestled, but I somehow managed to delete that photo when I got home).

The ice had fascinating effects on the sand. It was wonderful to see where there was both solid and liquid water, and the alien landscapes it was managing to produce . . .





If someone had told you this was a satellite photo of Mars, would you have believed them? I'm afraid I might! But it's just ice and sand. Look at the effects . . .


. . . and just next to the image above:


It's a funny thing, ice. Most materials - as far as I know - contract when they cool. But the water molecule is a very special thing. It's sort of Mickey Mouse shaped, two hydrogen atoms and one oxygen atom. The oxygen atom is much greedier for electrons than the hydrogen atoms are, so they spend, on average, more time with the oxygen - or to put it in another way, their "probability cloud" or where they will be is somewhat skewed towards the oxygen. This means that the oxygen has a negative dipole, the hydrogen a positive one - so, like a magnet, they will be attracted to each other (this wonderful article mentions an old description of two hydrogen atoms desperately in unrequited love with an oxygen atom). But this affects other water molecules too: the oxygen will also be attracted to hydrogen atoms of other water molecules, and vice versa, which makes the general structure stick together very nicely. Most molecules so small, and made of such small atoms as hydrogen and oxygen, would be gas (think of nitrogen, methane, carbon dioxide . . .). But water's a liquid, because of this dipole. And although they slip under and over and around each other a lot, their strong bonding also causes capillary action - just watch rain falling on the window and notice how a new drop will leap into the track of an old one, rather than make a new trail.

But once water goes solid, the molecules form hexagonal lines. Russell Stannard, in his book "Ask Uncle Albert", describes ice molecules (water molecules below freezing point, if you will) as being like long, long lines of people all sitting on each other's laps. This rigidity leaves plenty of gaps between those lines, which is why it expands. That's why, when water trickles into rocks and soil and then expands, we get weathering. I believe that's probably what's happened in the last picture above.

It was also very satisfying scientifically to notice that the water that remained liquid seemed to be coming from under the stones or sand - since ice expands, it's lighter than liquid water, and so it rises. Again, this isn't true of most liquids. But it's made pondlife and icebergs possible. Without this characteristic of water, I bet a lot of Earthly life would be hugely different.

And meanwhile, something's a bit wrong with the cliff . . .


But after only a short time of tramping across the beach I was starving. So I went to the cafe by the road. It was closed, but another was open. I bought scampi and chips and a hot chocolate with whipped cream and marshmallows. While I waited, I chatted with a family already scoffing chips there. They had two utterly adorable and very well-behaved dogs, who let me stroke them like cats, one hand on each. I honestly cannot recommend a better remedy for awful meetings!

Anyway, yes, I took my scampi and chips and hot chocolate and two sachets of tomato ketchup straight out there to the beach again. I went closer to that cliff . . .


And mostly stayed away from the water; can you imagine how slippery it was there? I plonked myself down on a rock, found a little well-like bit to put my hot chocolate in, and gobbled scampi for a while. It was raining slightly but I decided I didn't care. Surprisingly it really wasn't that cold.

Nevertheless, although the huge icicles hanging from the cliff were shedding water and indeed a few chunks of ice onto the sand, clearly the ice wasn't going to melt very fast!


What a sight!






While a chap nearby did a crazy dance, I photographed and photographed, my hand over my mobile to shield it from the rain - also to put it in shadow, since the picture went especially dark whenever I tried to include a bit of sky. I wondered how long it had taken those icicles to form. I remembered a phrase I'd heard in my first year of university, describing Antarctica, which really tickled me: "thermal inertia". I think the gist was that an increased amount of water vapour in the atmosphere would increase the size of Antarctica to some extent, since the water molecules would be likely to stick to it. If the size of Antarctica increases, that will increase its albedo - in other words, it will reflect away more sunlight. Of course, it will also raise the average temperature of Antarctica, too, just the same as if you pour warm water into a bucket of ice.

Another beautiful characteristic of water is its high specific heat capacity or enthalpy of melting. Heat is basically molecules wriggling about frantically due to having plenty of energy. (Absolute zero is of course when they stop moving altogether.) Now, because of the strong attractions between water molecules, it takes quite a lot to make them separate, or wriggle away from each other. That means that you have to put an awful lot of heat in before it'll warm up. The converse is true, too: water will take a long time to freeze, because it's got so much spare energy you had to put in to warm it up in the first place.

And that is why the Earth's surface is (contrary to how it often feels) remarkably similar in temperature all over. OK, OK, so hot countries seem incredibly hot and cold ones seem incredibly cold, but that's because we're adapted to a narrow range of temperatures, and what cosmologically speaking is only a slight variation seems extreme to a biological entity. When water evaporates from the equatorial regions, it carries plenty of heat to the poles. And those cold deep currents that start at the poles and head towards the equator remain cold, which again is useful, because more oxygen can dissolve in cold water - so cold water upwellings are particularly useful for marine and coastal life in the equatorial regions.

In short, if the Earth's oceans were oil, the heat would be far less evenly distributed around the globe!

I love the water molecule. I actually fell in love with it during A level Chemistry, and kept up with it for my A level project and several of my university units. If you want more of what it can do, check out this site - I've linked to it before, but it has some desperately gorgeous close-ups of snowflakes!

I'll leave you with the most spectacular photos of that cliff . . . and by the way, it was very nice to get home!


1 comment:

Peter said...

Wonderful post Alice :)

Beautiful images 8)