why is there ice under the Arctic or Antarctic, and the surrounding water not frozen?

Question

this baffles me because there's heouge blocks of ice under water and the surface is ice but not the water....:S

Answer 1

The position of the edge of the Arctic ice cap and ice shelves in the Antarctic is a balancing point between water at it's freezing point and ice at it's melting point, whether you are talking about fresh or salt water.

Neither salt water ice nor fresh water ice sinks, so the "blocks of ice under the water" doesn't make sense, unless you mean the 90 percent of an iceberg that is under the water line.

So, if we are dealing with salt water that freezes at -10 celsius and salt water ice that melts at -10 celsius, then the two coexist (the ice formed in colder weather and the water has come from warmer parts of the ocean). Freezing and thawing does take place daily if the sun rises and the temperatures rise sufficiently or if the ice is dirty, but it is mainly reversed after nightfall.

Answer 2

The Antarctic is a continent, so for the majority of it it has land under the ice.

For the Arctic, and the Antarctic sea-ice, salt water freezes at a lower temperature than fresh, so you can have a block of (freshwater) ice at -1 C floating in liquid salt water at -1 C.

Answer 3

David A has it pretty much spot on.
The wter in those areas that are fozen is cold enough, as you move further from the poles the watr gets warmer and so at some point there is a border where it is just in equalibrium, and as David point out, its dynamic business with some ice melting and some water freezing at that boundry. Further away from the poles it is simply to warm to form ice and closer it is too cold for the ice to melt. By the way when sea water freezes the ice forms it is pretty much salf free, but because it is in salt water, it freezes and melts at a lower temperature than it would in fresh water or out of water. This fact is used to deice roads by spreading salt on the fresh water ice for instance, and was used extensively in home ice cream machines of long ago, through in a bucket of crushed ice and a cup of salt and the mix cools to well below freezing allowing you to freeze the ice in a tub floating in the middle.

In the winter the extent of sea ice increased as more of the sea gets cold enough and in summer it retreats as the surounding water warms up. The edge is not a sharp line as wind, waves and water currents mix things up a bit hence the channels of free water inlets etc, that form.

Antarctica is a land mass and the bulk of the ice, several kilometres thick is firmly sat on that land, although there is surounding sea ice and ice shelves floating on the sea.

Global warming seems to be reducing the amount of freezing each winter and increasing the amount of melting each year. This is not good.

Answer 4

fresh water freezes at a higher temprature 0 celcius than salt water which has a lower freezing point. This means that for the sea to freeze the ambient temprature must be at or below the freezing point of salt water. The ice in the water does not melt as the sea water is cold and so the ice is held in suspension melting only very slowly

Answer 5

There is sea ice at both poles at all times of the year. During the winter, the sea ice cap expands as more water freezes. The open water that you are seeing is probably caused by wind or ocean currents moving the ice around.

Answer 6

Ice under the sea is fresh water and it freezes at a differant temperature than the salt water.

Answer 7

when the upper layer of lakes and ponds freeze due to access cold during formation of ice layer,water inside takes up heat due to latent heat of fusion released and also the layer of ice behaves like an insulator and that`s why aquatic animal survive under the frozen lake or pond.

Answer 8

Salt water will not freeze at 32. Iceburgs are made of fresh water which will freeze at 32.

Answer 9

Simply, because ice floats... that is a characteristic unique to water...

Answer 10

Because saltwater doesn't freeze. The ice on the land is freshwater.