When the main body of a shallow sea, such as the Southern North Sea,
reaches 4C does the SST cool faster because the maximum density has
been reached?

In article
,
Alan writes:
When the main body of a shallow sea, such as the Southern North Sea,
reaches 4C does the SST cool faster because the maximum density has
been reached?

Presumably, but cooling a body of water as deep as the North Sea
(calling it "shallow" is strictly relative) to 4C throughout its depth
takes a lot of doing. Until that happens, water cooled at the surface
will be denser than water below and tend to sink, to be replaced by less
cold water. Also less cold water will tend to invade from the north from
the North Atlantic. I suspect that in recent decades only in 1946-7 and
1962-3 would what you envisage have occurred. ISTR reading that by the
end of the 1946-7 winter there were ice floes off the coast of Belgium
and/or Holland.
--
John Hall
"Acting is merely the art of keeping a large group of people
from coughing."
Sir Ralph Richardson (1902-83)

On Feb 16, 10:56*am, John Hall wrote:
In article
,

*Alan writes:
When the main body of a shallow sea, such as the Southern North Sea,
reaches 4C does the SST cool faster because the maximum density has
been reached?

Presumably, but cooling a body of water as deep as the North Sea
(calling it "shallow" is strictly relative) to 4C throughout its depth
takes a lot of doing. Until that happens, water cooled at the surface
will be denser than water below and tend to sink, to be replaced by less
cold water. Also less cold water will tend to invade from the north from
the North Atlantic. I suspect that in recent decades only in 1946-7 and
1962-3 would what you envisage have occurred. ISTR reading that by the
end of the 1946-7 winter there were ice floes off the coast of Belgium
and/or Holland.
--
John Hall
* * * * * *"Acting is merely the art of keeping a large group of people
* * * * * * from coughing."
* * * * * * * * * * * * * * * Sir Ralph Richardson (1902-83)


That's what kind of prompt my question, I noticed that the current SST
for large areas of the southern north sea has reached this point:

http://www.wzkarten3.de/pics/Reursst.gif

So can I assume that it is also 4C throughout its depth? If so then
any subsequent cooling of the SST can't be replaced by less dense
water below, since there isn't any?

On Tuesday 16 Feb 2010 10:40, Alan scribbled:

When the main body of a shallow sea, such as the Southern North Sea,
reaches 4C does the SST cool faster because the maximum density has
been reached?

Not for the southern North Sea because the temperature of maximum density is
below the freezing point of -2C and the whole depth is cooled. However, if
you had referred to a salt-free inland lake you would have been correct.

--
Graham P Davis, Bracknell, Berks., UK. E-mail: newsman not newsboy
"I wear the cheese. It does not wear me."

On Feb 16, 11:03*am, Graham P Davis wrote:
On Tuesday 16 Feb 2010 10:40, Alan scribbled:

When the main body of a shallow sea, such as the Southern North Sea,
reaches 4C does the SST cool faster because the maximum density has
been reached?

Not for the southern North Sea because the temperature of maximum density is
below the freezing point of -2C and the whole depth is cooled. However, if
you had referred to a salt-free inland lake you would have been correct.

--
Graham P Davis, Bracknell, Berks., UK. *E-mail: newsman not newsboy
"I wear the cheese. It does not wear me."

Thanks for that, of course the salt changes the point of maximum
density!