Policy Question on Listserv

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From: Katryn Wiese (kwiese@ccsf.edu)
Date: Thu May 13 2004 - 09:02:27 PDT 

Message-Id: <s0a339c0.027@bat-gwmta.ccsf.edu>
Date: Thu, 13 May 2004 09:02:27 -0700
From: "Katryn Wiese" <kwiese@ccsf.edu>
Subject: Policy Question on Listserv

I receive the Pinhole Listserv, but do not understand how items get
placed in the e-mail. I cannot access the archives, as I have no
username and password. Is there information on the rules of this
service? I sent an e-mail Tuesday morning in reference to one of the
items. I've edited it and include it again today, as I noticed it was
not part of the most recent listserv.

RE: Polar Seawater
There's a great video, "Under the Antarctic Ice", that shows
high-salinity brines formed with sea ice (as the water converts to ice,
remaining water pockets/pools/inclusions are much saltier) dropping
through the ice into the seawater below. This extremely dense water
(super cold and salty) immediately sinks through the surrounding water
to the bottom, where it spreads out -- simulating the much larger-scale
bottom currents of the world's oceans. Aside from Red Sea and Med Sea
intermediate waters, the saltiest waters in the world are the deep
bottom currents, which originate in the polar seas from ice formation
and then move down and outward under all the world's oceans (Antarctic
Bottom Water moves into all the world's oceans; the Arctic Ocean Water
can only move into the North Atlantic). The movie illustrates the
process very well. AND...it shows the interaction between these
supercooled brines (much lower freezing point, so can get super cold)
and the normal cold polar seawater (also lower freezing point than
freshwater, but nowhere near what the brines experience). The proximity
of the supercooled brines causes the seawater to cool below its freezing
point, and frozen tunnels (brine channels) form as the brines sink
through the seawater. Amazing footage!

Website for information on video:
http://www.pbs.org/wnet/nature/underice/

Katryn Wiese
Department of Earth Sciences
City College of San Francisco
50 Phelan Ave Box S50
San Francisco, CA 94112
415.452.5061
kwiese@ccsf.edu

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