Young man in the second row, with the bad hair and his hand up, yes, what is your question? You want to know about supercooled liquids? Well, I can give a brief and probably [not quite correct but maybe close] overview....
Super cooling is a condition where a material exists in a state too cold for that material to be in that form. Water is an ever- popular example. We think that when water goes to or a little below 32 degrees F it freezes and turns into ice. Well, that not quite how it works. A couple of things have to happen for water to become ice, and only one is lowering the temperature; the other one is more interesting.... the water has to have a catalyst, usually in the form of a flaw or irregularity in it, to begin to form the crystals that make water a solid. Now in any daily form, this flaw is always present- a speck of dust, a material touching the water of an unusual shape, etc. So somewhere in that glass of water, or that jug of milk that is sitting outside when the temp. drops, something, actually millions of somethings, are available to start the formation of an ice crystal. But in a clean environment, one without dust or anything solid, water is often found at temperatures well below freezing and even well below zero F. Water droplets at very high altitudes are just hanging around, waiting for something to nudge them into 'formation' as crystals WHEN SUDDENLY, an aircraft flies through the air and all the water it touches instantly turns to ice..... on the plane of course.
The other place is in a very clean, still environment such as a laboratory. Coolest thing ever is watching a beaker of water suddenly freeze into a solid block of ice. It happens in less than a second and the ice takes on whatever shape or state it was in when it is nudged, bumped or contaminated. Amazing....
Tomorrow, supersaturated liquids, when liquids hold more material than they can hold....
Brian
Hey Brian!
Tell us kids about super cooled water, that's always fun.
