Thursday, July 31, 2014

Word of the Day -- Polynya

A polynya (common US spelling) or polynia (common UK spelling) /pəˈlɪnjə/ is an area of open water surrounded by sea ice. It is now used as geographical term for an area of unfrozen sea within the ice pack. It is a loanword from Russian: полынья (polynya) Russian pronunciation: [pəlɨˈnʲja], which refers to a natural ice hole, and was adopted in the 19th century by polar explorers to describe navigable portions of the sea. In past decades, for example, some polynyas, such as the Weddell Polynya, have lasted over multiple winters (1974–1976).

I first came across this word in a book back in the late '70s and it has stuck with me ever since.  It is such a neat concept.  I've kept it in my back pocket ever since and bring it out at parties.  Yeah, I'm a geek.  :-)  But it always seemed it would be a good segue into an adventure, using polynyas as water portals...

Polynyas are formed through two main processes:
  • Sensible Heat Polynya: this is thermodynamically driven, and typically occurs when warm water upwelling keeps the surface water temperature at or above the freezing point. This reduces ice production and may stop it altogether.
  • Latent Heat Polynya: is formed through the action of katabatic wind or ocean currents which act to drive ice away from a fixed boundary, such as a coastline, fast ice, or an ice bridge. The polynya forms initially by the first year pack ice being driven away from the coast, which leaves an area of open water within which new ice is formed. This new ice is then also herded downwind toward the first year pack ice. When it reaches the pack ice the new ice is consolidated onto the pack ice. The latent heat polynya is the open water region between the coast and the ice pack.

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