Latent-Heat (Coastal) Polynyas

[Andrew]

The wacky world of the National Snow and Ice Data Center *and* the Open University of the UK

nsidc.org/cryosphere/seaice/characteristics/polynyas.html

[Andrew]

Fairly obviously the incorrect useage of latent heat is quite well established in the ice research community

This site is Australian

www.acecrc.sipex.aq/access/page/?page=01480fac-bc82-102a-8ea7-0019b9ea7c60

[nonentropic]

this is the crap you get a year 8 school. lots of flash words and processes some are correctly attached to processes some less so but all very interesting to 12 year old kids and their science-less teachers.

relax all this was the standard when most of us came through.

[Andrew]

In relation to the ongoing saga of the article at NSIDC that is supposedly in the process of being reviewed for some corrections to make it easier to read and more technically correct, I wrote to NSIDC about the so called latent heat polynya. This term seems to have first appeared in 1988.

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Dear Shannon

I think along the way, NSDIC is going to have to rethink the notion of the so called latent heat polynya.

If there is a very cold offshore wind, sensible heat is removed from the warmer water which is at the freezing point. This sensible heat is now in the air blowing across the sea and ice, and less energy is contained in the more highly ordered ice phase, even though it is the same temperature upon formation as the water from which sensible heat was removed.

The latent heat of fusion of water is not warming the ocean or anything else more than water that is infintessimally warmer than ice

All that is happening is that the presence of the water, from which energy is extracted at a constant temperature, enables the cold wind to be in contact with warmer liquid water heating the atmosphere, via a sensible heat, for longer than if the latent heat was not present, and ice formed and the ice surface temperature plunged compared to the water. Quite obviously in a coastal polynya the warm water is being cooled by the cold wind and because the ice gets blown further out to sea more warm water is exposed to carry on the polynya. All of these diagrams everywhere showing latent heat travelling upwards away from water are a bit daft! :-)

The terms sensible heat and latent heat polynyas should be avoided in favour of the terms of something like: convection polynya, and offshore breeze polynya.

Yours sincerely

Andrew