The question as it appears in the 06/26 edition of Specs & Techs from GlobalSpec:
You fill up an ice cube tray and put it in your freezer. The next day you open the freezer and pull out the tray to get some ice. A small icicle is protruding upward from the top of one of the ice cubes in the tray. You check to see if something was dripping on the tray but find nothing that could have caused this odd ice formation. What caused this ice spike to form?
(Update: July 2, 10:11 PM EST) And the Answer is...
Ice cubes freeze from the top down. Since water expands when it freezes, pressure can build up if the surface layer doesn't move. Usually the ice layer on top will simply move upwards as the water freezes and expands however sometimes the top layer of ice will stick to the sides of the tray and not move upwards. Pressure builds until the water can penetrate a weak spot on the surface ice. When this happens the water is forced upwards by the pressure through the fissure in the surface ice. An icicle builds as the pressure below forces water to the surface where it freezes. This continues until the ice cube is completely frozen and the expansion stops.
|