wrote:
Kirk Gordon wrote:

wrote:

There is a reason why it is around 28.4 degrees F at high
latitudes, see below.

Here is an explanation of latent heat of fusion:

http://en.wikipedia.org/wiki/Latent_heat_of_fusion
...
About three and one-half degrees F below the freezing point of pure
water.
...
I am familiar with the concept of freezing point suppression.

Regarding the Arctic ice cap being freshwater, that is partly
because when seawater freezes the salts are mostly 'excreted'
(for want of a better term) from the ice. Some of the Arctic
ice cap is freshwater because it is formed by precipitation
on top of the sea ice.

Based on the following information it would appear that today the
freezing point of seawater is around 28.4 degrees F.

http://en.wikipedia.org/wiki/Freezing-point_depression
http://en.wikipedia.org/wiki/Sea_water
http://www.newton.dep.anl.gov/askasc...9/gen99263.htm
http://www.csgnetwork.com/h2ofreezecalc.html

If the salinity were twice what it is today then the freezing
point would be about 25 degrees F. That does not agree well
with the assertion that the average ocean temperature was
30 to 40 degrees cooler ten thousand years ago, or ever.


I'm not a great fan of Wikipedia; but even the articles you cite say
that salinity varies a lot. If the water near Iceland really freezes at
28.4, then that's probably because those same waters are some of the
freshest.


The articles indicate average salinity of seawater today is near
35 and that corresponds to a freezsing point of about 28.4
degrees F. The reason the ocean temperature is at 28.4 F
at high latitudes is because 28.4 degrees F is the freezing
point of ocean water.


Although, as I understand what I've read, no one suggests
that the sea is freezing around Iceland or Greenland. ...
If the sea water
cold really freeze at 28.4, then there'd be coastal ice around Northern
places in winter, just like you see in lakes and ponds. I'm not aware
that any such thing exists, or ever has existed.


Have you heard of the Arctic Ice Cap? Have you seen pictures of
the ice that forms on the shores at Northern Latitudes? Have
you heard of 'Warm Water Ports'?


In places where salinity is high, freezing points will be much
lower.


Sure, like the Dead Sea. The oceans, being contiguous, have far
less variability. I daresay you will not find anywhere in the
oceans where the salinity differs from the average by a 30%,
or stated differently where the freezing point is more than
one degrees F below the average, and that will be in warm shallow
seas.


And, as I said earlier, when lots of the Earth's total water
turns to ice, then there's less liquid water to contain the same amounts
of salt. Salinity rises, freezing points drop, and you still have only
fresh water in a solid state, with sea water increasingly resistant to
cold.


And as I stated earlier, if the ocean volume were to drop in half,
with the total dissolved salts remaining the same, the freezing
point will only be about 25 F. That is still too high for an
average ocean temperature 40 degrees F cooler than today and
a 30 degree difference would seem highly improbable.

Aside from the observation that your earlier assertion ranges
from improbable to impossible, you haven't presented and one
presumes cannot find any credible source stating that the
Earth's average ocean temperature was ever 30 or 40 degrees F
below what it is today.


In fact, it occurs to me that there may be some self-governing
mechanism at work. No matter how cold it gets, there might ALWAYS be
liquid water on Earth. Each little bit of sea water that evaporates,
freezes, and then returns to Earth in a fresh and frozen state, leaves
its salts behind in the water that remains liquid, thereby protecting
that liquid from freezing. It's possible that even the most extreme
cold that can occur on this planet won't be cold enough to freeze all
the water, or to freeze out all the life-forms.


I suggest you read up on osmotic pressure and how it affects
living cells.


That would also work if sea water actually "excretes" its salt,
though I've never heard of that before, and have a hard time seeing how
it could work.


You should have studied Chemistry in High School.


I don't think heat of fusion has much to do with overall
temperatures. That's really just a little bit of hysteresis in the
freeze/melt cycle. But heat that has to be withdrawn from water to
solidify it also has to be returned before the water can re-liquify. A
zero sum game. And, since Earth's water is part liquid, and part solid,
the game is always giving at the same time it's taking. I can't see how
that would make much difference in average temperature.


Do you understand that the heat of fusion is absorbed or released
at (near) constant temperature?


It might make a
tiny difference in how much water is solid, and how much is liquid, at
any given temperature; but it doesn't change the total kinetic energy
involved.


You should have studied Physics in High School too.


And you should have studied manners. End of discussion for me.

KG