2007-11-06 22:16:16 · 8 answers · asked by Anonymous in Science & Mathematics ➔ Physics
when the upper layer freezes (because of the cold temperature outside) it creates a kind of wall that keeps the water under it warmer because it is not in direct contact with the cold temp outide. Therefore, the water under the frozen layer won't freeze because its not as cold
2007-11-06 22:21:22 · answer #1 · answered by Anonymous · 0⤊ 0⤋
Heat diffuses slowly through the ground because it's a good insulator, so water solidifies on the surface (where it contacts the air) first if the air drops below freezing in bodies of water sunk into the ground. In an ice tray, though, it freezes on the wall almost as fast because the wall is too thin to insulate effectively. True ice floats, but ice forming on a cold surface generally sticks to it, so that's not really the main reason.
2007-11-07 00:59:43 · answer #2 · answered by Dr. R 7 · 0⤊ 0⤋
Everybody is sort of dancing around the total answer, bits and pieces. Obviously freezing occurs at the surface because that is where the exposure to the subfreezing temperatures occurs. Water is a special substance, dfferent than most, in that the solid is LESS dense than the liquid, so when it freezes the ice doesn't sink and the entire surface eventually freezes solid. The frozen surface basically insulates the main mass of water underneath from exposure to the cold.
If ice was denser than liquid, it would sink, and new water from below would be exposed to cold, eventually leading to the entire body of water turning solid.
2007-11-06 22:30:15 · answer #3 · answered by busterwasmycat 7 · 2⤊ 0⤋
Two reasons:
A body of water has more or less constant temperature throughout the year, but the layer closer to the surface is exposed to the cold weather most. Ice has lower density than liquid water so it rises to the surface (a good thing 'cause otherwise there would be no life on Earth)
2007-11-06 22:21:37 · answer #4 · answered by Kimon 7 · 1⤊ 0⤋
Because water density changes with temperature but not in a linear way. At 4ºC (39ºF) the water is "heavier" and goes to the bottom and the top water is colder, freezing.
2007-11-06 22:20:55 · answer #5 · answered by Valerie_Summer 2 · 2⤊ 0⤋
The surface takes a direct hit.
Do you know how cold it would have to be and how long it would take for a large body of water to freeze in it's entirety?
2007-11-06 22:20:04 · answer #6 · answered by Anonymous · 0⤊ 1⤋
because of the density of ice is less tha the density of water,so the ice floats, and protects the sea life from freezing,
2007-11-06 22:25:43 · answer #7 · answered by lynn 2 · 1⤊ 0⤋
it is because of the anmolous expansion of water 4m 4 degree to 0 degree.
2007-11-06 22:20:45 · answer #8 · answered by ommidikra 2 · 0⤊ 0⤋