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Why dont we have frozen Oceans if...


Big Bad Voodoo

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Salt water does freeze, actually, but the temperature must be much lower. How much lower depends on the salt concentration. Also, we do have partially frozen ocean water at the poles.

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Is the ice a the poles salty or does the salt precipitate out during the freezing of the water?

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...water freezing point is 0 C?

Big Bad Voodoo

Because 0 degrees is the first point at which water exists as a solid, not the point where water magically turns into ice - in fact it's called "the triple point", because water can be in a gaseous state and still be 0 degrees.

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Water under pressure behaves differently as well. Also must have something to crystalize around

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The point is that at zero degrees C water sublimates into gas if there is no pressure, and melts into water at atmospheric pressure.

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Under greater pressures water can remain solid at higher temps. Sea ice is fresh enough to drink as it expels salt as it freezes

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Part of why the ocean does not freeze is due to salt content. Which lowers the freezing point to around -2 C. Most sea ice is actually fresh water with the salt squeezed out of it, I believe.

Part is convection. The ocean water as it gets colder will tend to sink, and warmer water will come up. Thus, depending on the ocean depth and temperature, the whole region of the ocean must get close to freezing before the surface will freeze. Which is a lot of energy.

Part is that the ocean moves. So that warmer water moves north and pushes colder water around and back south.

It is a very dynamic heat system and it is very hard for the ocean to begin to freeze in any one place.

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Part of why the ocean does not freeze is due to salt content. Which lowers the freezing point to around -2 C. Most sea ice is actually fresh water with the salt squeezed out of it, I believe.

Part is convection. The ocean water as it gets colder will tend to sink, and warmer water will come up. Thus, depending on the ocean depth and temperature, the whole region of the ocean must get close to freezing before the surface will freeze. Which is a lot of energy.

Part is that the ocean moves. So that warmer water moves north and pushes colder water around and back south.

It is a very dynamic heat system and it is very hard for the ocean to begin to freeze in any one place.

Yeah which i why there is a theory that rapid melting of Greenland and Antarctic ice sheets due to global warming could interrupt oceanic convection currents and send us into an ice age. Not sure how valid this theory is
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Yeah which i why there is a theory that rapid melting of Greenland and Antarctic ice sheets due to global warming could interrupt oceanic convection currents and send us into an ice age. Not sure how valid this theory is

From what I've read it is possible, but not very likely. It is one of those "mousetrap" arguements, (Mousetrap the 1970s game) where all the parts and actions would have to line up perfectly for it to happen. So basically it won't.

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From what I've read it is possible, but not very likely. It is one of those "mousetrap" arguements, (Mousetrap the 1970s game) where all the parts and actions would have to line up perfectly for it to happen. So basically it won't.

Yeah, I'm no expert on this but I would tend to agree with that though I have heard that as a possible explanation for the younger dryas
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Well whatever happens when the ice sheets melts, I doubt we will like it.

Especially if you own beachfront property
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As well as the reasons given to you, water has another, unusual property. In most cases the solid phase of a chemical is more dense than the liquid. When you start to freeze it the ice sinks to the bottom and the freezing process occurs from the bottom upwards. The sinking of the ice (and the colder, more dense, liquid near freezing point) help to cools the entire liquid.

This does not happen with water. Water is at its most dense at around 4oC, whilst still liquid. This means that the ice floats at the surface. Warmer water sinks. This is why fresh water lakes (and even fish ponds if they are deep enough) do not freeze solid even when the air temperature is well below freezing. If the body if water is deep enough the temperature at the bottom will remain at 4oC.

Edited by Waspie_Dwarf
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As well as the reasons given to you, water has another, unusual property. In most cases the solid phase of a chemical is more dense than the liquid. When you start to freeze it the ice sinks to the bottom and the freezing process occurs from the bottom upwards. The sinking of the ice (and the colder, more dense, liquid near freezing point) help to cools the entire liquid.

This does not happen with water. Water is at its most dense at around 4oC, whilst still liquid. This means that the ice floats at the surface. Warmer water sinks. This is why fresh water lakes (and even fish ponds if they are deep enough) do not freeze solid even when the air temperature is well below freezing. If the body if water is deep enough the temperature at the bottom will remain at 4oC.

I had a teacher in school tell me that were it not for that property of water there would be no life on earth as the only reason life survived on the early earth was that bodies of water didn't completely freeze
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Because it is not sufficient that the air temperature is 0, you also need distilled water at that temperature in all layers. Depending on the aggregates to the water it may not freeze until -40 C (i.e. antifreeze).

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And now that the science is understood, it is time for the Icy Finger of Death!

http://www.youtube.com/watch?v=r4cX2EPt2zE

Also, only the south pole melting will appreciably raise the ocean levels. Since their is no land at the north pole all the ice is floating on the water. Since the amount of ice that floats above the waterline is equivalent to the volume chance when the ice freezes, as the ice melts you don't get any net change in water level.

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I thought that was partly inside the Arctic Circle, but not considered part of the polar area? I'm pretty bad at geography so I could be wrong. But yeah, ice on land melting does mean a pretty straightforward ocean level raise, for sure.

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