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Thursday, 15 January 2015

Ice spikes



Last March a triangular ice spike appeared on our bird bath.  I was reminded of it by Roy Spencer's recent post on ice spikes he has observed in Alabama. He also links to this laboratory study which used ice cubes in a tray, but presumably the mechanism is similar.

In the case of an ice spike forming in an ice cube tray, water first freezes at the surface, starting at the edges the cube, and the ice subsequently expands laterally until only a small hole in the ice surface remains. Then the continued freezing of water beneath the surface forces water up through the hole, where it freezes around the edge of the hole to form the beginnings of a hollow tube. Continued freezing forces water up through the tube, where it freezes around the rim and lengthens the tube. At some point the tube freezes shut and growth stops. 

As you can probably see, there was snow on the ground and the bird bath is quite shallow which seems to help. Wikipedia has more info.

6 comments:

James Higham said...

That's more fascinating than crop circles.

Roger said...

Spiking a poor birdy's drink?

Oxters remained entirely dry.

Demetrius said...

Does it work with gin?

Weekend Yachtsman said...

Years ago (MANY years ago) my brother and I used to fill glass lemonade bottles completely full of water - no air gap at all - screw the lid on tightly, and leave them out in the garden in frosty weather.

What happens is, the water expands when it gets below 4C, but can't go anywhere because of the bottle, so it supercools until the bottle bursts, whereupon the whole lot freezes instantly in the act of expanding out into the air. You get the most beautiful feathery three-dimensional ice sculptures.

Oh, and you also get a whole lot of broken glass in the garden, but only grown-ups worry about such things - I did say it was a LONG time ago.

A K Haart said...

James - and more natural.

Roger - spiking the water is a way to get birds for the pot in these hard times.

Demetrius - we've never tried gin in the bird bath, but it could be interesting.

WY - sounds like fun. We never tried that although we did put fireworks in bottles.

Weekend Yachtsman said...

Spiking the water with gin?

Someone's been reading Roald Dahl again...