Okay so it was more of a walk and the ice sheets are just some patches of snow that haven’t melted yet – but we did go to look at the last bits of snow that were left on the mountains, with a theory as to why they have lasted so long. It seemed to me that it had been fairly warm for long enough to melt all the snow on the mountain and I wondered why these few bits were left. My theory was that under the ice there was a hollow, the ice there having melted, and that hollow was now insulating the ice from the warmth of the ground below. The shiny surface of the snow and ice would reflect the suns heat. So a bit of conduction, insulation, radiation all going on – quite a nice bit of physics for teaching, if it were right.
We started off at the little car park at the bottom of Castell Dinas (http://www.castlewales.com/ddinas.html) and climbed up to look at the ruins of a castle (the highest one in England and Wales -http://en.wikipedia.org/wiki/Castell_Dinasl) and earthworks. James thought it would be a good place for playing war.
Then we started the long walk up a series of ridges. There were pockets of snow either side of the ridge but we went towards the ones below Waun Fawr. Each step up the ridges gave better and better views, shame it was a bit hazy. Just below the hills was the gliding club (http://www.blackmountainsgliding.co.uk/) and the gliders were out in force, six up at one time.
We stopped for lunch and then carried on up the ridges. Eventually we got to the summit of Waun Fawr at 810m. It was a bit strange, a lump of concrete stuck on the top of what looked like a very old trig point pillar. The views from the top were fantastic – we should have had this with us: http://www.viewfinderpanoramas.org/panoramas/WAL/WAUNFACH.GIF because we could see the Bristol Channel, Malverns, Brecon Beacons and so forth.
After we got to the top we headed down to the snow patches. I dug a hole, and James and Jacob dug out the snow, but the bottom wasn’t hollow. So James started to cut some slabs off the side, but they weren’t hollow either. That shot that theory down then. The ice was quite slushy, only some of it was snow, with most of it seeming to be ice, and grey rather that white. It might be that these parts all have water feeding into them, but that’s an experiment for another day.
On the way down we had gliders coming over our heads. It was really something to see, the shadow of the glider just metres away from the actual object. You could hear some weird sounds as they flew a few tens of metres above our heads.
We spent quite a while out today in total. When we eventually got back to the car our feet were throbbing so it was off to get some ice creams and some pop. The screen shot is of this online tool “Where’s the path?” (http://wtp2.appspot.com/wheresthepath.htm?lat=51.963372&lon=-3.143206). You plot on an OS looking mapping while it duplicates it on an aerial photo – seems really good and reckons we did 5.66miles today….they’re rubbish these computers…it was loads further than that!