Thread: water under the ice

Hi falks,

I read this in a book
the water under the ice in both poles has the same temperature and equals 4 C ....

No problem with the both poles BUT do you agree about the 4C temperature????
I am repeating do u agree that the temperature pf the water underneath the ice in both poles is 4C?
AND WHY????

No it is not.

There are two possibilites:
a) The book is wrong.
b) You have misread the book.

The maximum density of water occurs at 4 deg. Celsius. I suspect this is what you have read and been confused by. This is borne out by your confusion that places water under the ice at both poles. The bulk of the Antarctic ice is on land.

As a point of information the Northern Polar ice may all be gone within a decade or so.

For the north pole I could agree...

Water, like most liquids, gets denser as its temperature lowers (the molecules stop vibrating so fast and come closer to each other, that whole deal)...

at 4C water is at its most dense. At that point, the water on the top cools but is less dense due to the partial creation, if I am correct, of ice crystals with a maximum density lower than liquid water (due to the hydrogen bonds holding water together in a hexagonal crystal with large pockets of nothingness between the molecules) and so the colder water will stay on top in contact with the cold material (be it ice or cold air). This cold water may completely solidify into ice or just remain cold. Therefore, unless the body is shallow (or the water has nearly frozen all the way to the bottom), there should be:

<air>
<possibly ice, not neccessarily>
<liquid water with a temperature of less than 4C>
<liquid water with a temperature of 4C if there is enough liquid water present>
<bottom>

...if that makes sense.

...just an assumption, though. Thats the way that any other body of water works and I don't know of any reasons that the Polar ice cap would behave any differently. If you can find something to prove this wrong then please post it.

-Ajain

Originally Posted by almirza

Hi falks,

I read this in a book
the water under the ice in both poles has the same temperature and equals 4 C ....

No problem with the both poles BUT do you agree about the 4C temperature????
I am repeating do u agree that the temperature pf the water underneath the ice in both poles is 4C?
AND WHY????

The deepest fresh water under ice is at 4C because it's most dense. I don't know about salt water, but it's freezing point is 0F and not 0C.

Ok
Tell me
Which part of the water freezes first , the bottom or the surface???

The book is not in English but it says:
"The water under the ice in both poles has the same temperature which is 4 degree Cels. because the density of water is a maximum at that temp. and as water cools it becomes solid and float on the surface".

Even if the water in liquid state is less than 4 degree cels. its density is higher than ice . So even if the water's temperature is less that 4C the ice will float on its surface....

Am I mistaken???

i doint think so
and could u please stop using so big letters and colors?

Originally Posted by almirza

Ok
Tell me
Which part of the water freezes first , the bottom or the surface???

No body answered my this question .......

Thw top. Observe it for yourself. Ice is actually less dense than water so it floats. Thank God, says the fish.

Originally Posted by silkworm

Ice is actually less dense than water so it floats. Thank God, says the fish.

Hence do we

However, you have to cool water way below 0 C to transform it to ice, in case it contains SALT.

Water containing a lot of salt can still be fluid at -20 C

YES water under ice cannot further decrease from 4 deg celcius this is because of a unique property shown by water.
water has max density at 4 deg celcius
ice being at 0 deg celcius is lighter than water at 4 deg celcius
hence ice floats on water and ice being an insulator of heat does not allow heat exchange between water (at 4 deg celcius) and outside environment
hence water below the ice layer remains at 4 deg celcius
AND THATS THE FACT