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|SPIGYN RHEW (pibonwy Bally-Dorsey) |
|Dyddiad cyhoeddi : 21-03-2015||Hits : 669|
|Taken back in January 2011. Do you remember the bitter cold weather, I still have not found out quite how it would have formed. My e-mail at the time ran something like this:-|
I'm puzzled by my observation of an Ice feature that has appeared in the animal drinking tub in the garden. I can't think how it might have been formed. There is nothing to drip into the tub, and there was no dog with it's tongue stuck to the ice.
Why would it have formed? Attached pictures show what I'm taking about. How can frozen water defy gravity? Any ideas would be welcome (before I go mad).
Cyfrannwyd y llun gan Steve Roddick
Mae'r ateb yn fan hyn: http://en.wikipedia.org/wiki/Ice_spike
|Enw'r awdur|| : Ann Corkett|
|Dyddiad|| : 13-05-2016|
Published at 12:01AM, February 17 2016
Icy weather can sometimes create intriguing phenomena. Nigel Louth in Leyton, London, sent a picture of a small pool of frozen water in a children's play table that had been left outdoors, which featured an odd piece of ice sticking up, rather like a triangular flag over a hole at a golf course.
"I am unable to explain why, what looks like a miniature iceberg, has formed" Mr Louth wrote.
This was an ice spike - a needle or wedge of ice protruding from small frozen pools, puddles, pots, birdbaths and even ice cubes in a freezer.
Sometimes, ice spikes have an arrowhead or a flag-shape ending, and the spikes can form upright, at an angle and be of varying lengths — there have been reports of some spikes reaching about 15cm (6in) high on mountains in Hawaii.
The phenomenon is created by the expansion of ice, by about 8 per cent, when it freezes. In freezing weather, a sheet of ice on a pool spreads from the sides towards the centre, until eventually only a small hole is left on the frozen surface.
The ice starting to form just below the hole can push water up through the hole, forming into a hollow spike of ice, rather like a straw. As more water is pushed up the straw of ice, it freezes around the rim at the top and so the spike grows longer. Eventually, the whole tube of water freezes solid, leaving a marvellous pinnacle of ice standing up.
Ice spikes can also be made in ice-cube trays. It is best to use distilled water, because salts in tap water tend to inhibit the process. Freezing temperatures between minus 5C and minus 8C (23F to 18F) are ideal, and a fan in the freezer also seems to help.
“The tallest spike we’ve seen growing in an ordinary ice-cube tray was 56mm (2.2in) long,” said Kenneth Kibbrecht at Caltech California Institute of Technology, who has studied this phenomenon.
Magnificent time-lapse footage of an ice spike forming in an ice-cube tray can be seen at bit.ly/1POjtLy