Why is ice at the top of the sea? Surely as its colder the deeper down you go it should be there?

Question

Think its something to do with oxygen but not sure?

Answer 1

There are two elements to your question which need separate answers.

Ice is slightly less dense than water and so always floats.

Temperatures usually decrease as sea depth increases and the water forms into successively colder layers. The Challenger Deep, which is the deepest place in the ocean, is in the Marianas Trench in the Pacific Ocean, near the Phillipines. The lowest temperatures recorded here is +1.5 degrees Centigrade at around 3,000 metres. This is above the freezing point of pure water (0 Degrees C) and much higher than the freezing point of sea water, which is about -2.2 degrees centigrade.

However even if the water temperature reached -2.2 degrees C, the increased pressure experienced as the depth increases would prevent ice from forming.

Answer 2

Ice is at the top of the sea because water actually expands as the temperature drops below 4 degrees Celsius, making the solid form less dense than the liquid. This is why ice floats. Water is very unusual in this regard, but if it didn't behave this way, life on Earth would be very different indeed!

Answer 3

Could it be that the core of the Earth is very very very hot like molten lava, and the rock formations and water are keeping the heat in towards the center of the Earth. The sun heats the air or the outside and the lava heats from the inside, out and between the two is the ice layer. After all what was the big BOOM?

Answer 4

OK, first of all, let's deal with why you are asking this.

I'm guessing that you're basing the question on the fact that warm air rises. If warm air rises, why doesn't the warm water rise above the cold water (ice) thus making the ice sink.

Is that where you're coming from?

It's a perfectly reasonable assumption really. The reason it's wrong is because the statement "warm air rises" over simplifies what is actually happening. It's more accurate to say "warm air rises above cooler air", but even that doesn't explain why.

The reason warm air rises above cooler air is (as you've probably guessed from reading the other answers) because of density.

As air warms up, it expands and becomes less dense than cooler air - thus it rises above it. So, it would be more accurate to say less dense air rises above more dense air.

As bizarre and contra-intuitive as it sounds, ice is *less* dense than liquid water. Thus, from a density point of view, it is following the same rule as air - ice rises above the more dense liquid water and floats on top of it.

Does that answer you question?

Answer 5

Ice is less dense than water, so it floats on the top. As you go deeper, the pressure increases, and prevents freezing.

Answer 6

Because at the bottom of the ocean the water is under greater pressure, this reduces the level at which the water will freeze.
One of the unique properties of water is that it actually expands when it freezes, unlike most liquids. Therefore at higher pressure it will strive for the state that takes up the least volume, i.e. liquid.

Answer 7

Its just that ice has large gaps in its molecular structure that it becomes voluminous and less dense than water. So, ice will float in water. Even if ice is formed deep down, it will come up.

Answer 8

Ice is lighter than liquid water. It is one of the few solids that is less dense than its liquid form. This is because when the water crystalizes, the electric charge on its molecules push them further apart.

-Dio

Answer 9

Because ice floats

Answer 10

It is, cold water holds more oxygen than warm water, therfore more likely to float.

Actually according to scientists water should really be a gas.