On 7 Jan, 22:50, John wrote:
On Wed, 07 Jan 2009 22:09:19 +0000 (GMT), "Dave Liquorice"

wrote:
On Wed, 7 Jan 2009 18:03:44 -0000, Gary L wrote:

A bit in the local paper today.

Must be only brackish water if it's freezing at only -10C. 0F, the
freezing point of salt water, is nearly -18C. Still don't let facts get in
the way of a good story. *B-)

-18C? A saturated salt solution freezes at -21C and seawater is far
from that. *The salt solution used for 0F was ammonium rather than
sodium chloride.

A quick google gives a figure of around -2C for ocean seawater
although I assume convection and other effects mean a lower air
temperature would be required for surface freezing.

John

-2C about right for open sea, but it's even higher for many harbours
due to fresh water on top. Padstow harbour got in the news for being
frozen. The gates to the inner harbour were shut, and the river
flowing into it makes the surface virtually fresh, so it's little
different to a pond freezing over. A point that was made on the local
news report, which is good to see.

The very low humidity on the night of 6th/7th helped.

Graham
Penzance