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How would you make ice that pops in the glass the way glacier ice does when a drink is poured over it.
- Aaron (age 35)
I don't think there's anything special about "glacier ice" -- it should be very similar to any other kind of ice.
Ice will crack when a room-temperature beverage is poured over it due to thermal stress. Like other solids, ice shrinks when it gets colder, and expands when it is warmer. If ice comes out of the freezer very cold and you pour a warm beverage over it, the outer layers of the ice will warm first and expand. Heat takes time to conduct inside the ice, so the insides of the ice cubes won't expand. The ice will crack under these circumstances because it is brittle and cannot change its geometry without breaking in pieces.
The most sure-fire way to make crackly ice is to get it really cold, and to pour a hot beverage over it. Don't make the ice cubes too small (ground up as fine as grains of sand would probably not generate a big enough strain to make big, noisy cracks -- snow doesn't make a lot of noise if you pour water on it).
(published on 09/17/06)
Follow-Up #1: freezing bottles
What was said about the ice getting smaller as the temperature gets colder is true, but as the temperature falls ice first contracts and then expands, this is why a full plastic bottle left in a freezer for a long time will eventually burst.Right?
- Steven Groves (age 15)
The expansion which often bursts bottles occurs almost entirely in the conversion from liquid water to ice. There's a tiny bit of expansion also on cooling from 4°C to 0°C for pure water.
(published on 10/13/06)
Follow-up on this answer.