ICE STALACTITES
| Home | Gallery | Field Guide | Diving | Journals | Sponsors/Thank Yous |
Looking
up slope, the diver swims under a six foot thick sea ice ceiling in shallow
water under twenty feet in depth. The seafloor is carpeted with clusters of
newly formed anchor ice. The sea ice ceiling is mounded and has ice stalactites
hanging down. Sea ice stalactites are hollow, tapering structures up to
several feet long. As ice forms from seawater, the salts do not become part of
the ice lattice and remain as a dense and cold brine solution.
This dense chilled brine drains downward from tiny brine channels and pools in
the sea ice and enters the near-freezing seawater below the sea ice (the seawater is
not as cold as the brine however). Ice forms around the draining cold brine
streamers, thus forming a hollow ice stalactite. Sometimes this brine streamer
can be seen draining downward from the tip of the stalactite; it has a different
density than seawater which makes it visible.
Once the
ice tube is formed, heat is horizontally transferred between the brine and
seawater through the ice wall of the stalactite. However salt cannot be
laterally transferred. After a tube forms, the relatively warm brine is in
contact with the inner ice wall and the brine is above its equilibrium
temperature. To reestablish its phase equilibrium, the brine must be both
cooled and diluted which is accomplished by melting the inner tube wall with the
heat of melting coming from ice forming on the outer wall. Thus the lengthening
sea ice stalactite grows on the outside while ablating on the inside.
| Text ©Peter Brueggeman. Photographs
©Norbert Wu.Photographs may not be used in any form without the
express written permission of Norbert Wu.
Norbert Wu no longer grants permission for uncompensated use of his photos under any circumstances whatsoever;
want more info?
|
