Wednesday, November 25, 2009

When waters collide

     This is where the water wrestles with itself.
     Nature has drawn a loopy circle through the Southern Ocean well away from, but around, Antarctica. The line wanders anywhere from north of 47 degrees latitude to south of 60 degrees, and meanders from season to season, year to year. It’s where the deep-chilled brine of polar surface water slips beneath the warmer waters of the north. The result of the battling waters is the Antarctic Convergence.
     Although it is a virtually invisible – and somewhat shifting – line, the Convergence forms perhaps the most imposing quarantining of species in the world. Consider that in an area larger than North America there are just 39 of the more than 9,000 species of birds on the planet. This time of year the Convergence – alternatively, the Polar Front – sees surface waters around Antarctica become diluted with fresh water from ice melt.
     The mix and churn of the warm and saltier water from the north with colder Antarctic water conjures up great blooms of algae. Tiny shrimp-like krill feed on the algae, and then become the main staple of dinners for everything from penguins to whales. On board a ship, there’s no noticeable difference from the convergence itself beyond a dip in temperature. While the Convergence is often associated with violent seas, the roller coaster conditions are often just a coincidence.

     And we are taking a shortcut through the most notorious coincidence. The Drake Passage overlaps with the Convergence and marks the spot where winds and currents circling from the west out of wide-open seas come barreling between the tip of South America and the Antarctic Peninsula. Shortly before sundown last night we passed by the bottom of Tierra del Fuego (pictured) and into the Drake. The swells here are decidedly larger than what we saw before entering the Drake. Waves wash over the back deck and fewer people wander out to the bow. It has become a seesaw. But by Drake standards, the weather and seas are rather calm. And those who stand watch are rewarded with the sight of an albatross.

2 comments:

Andrew said...

can you take pictures of how big the swells are? cool pics so far...i think your trip should be the next hit series on discovery...

woozieman said...

Don't know if you're green from seasickness right now, but I'm green with envy. What an adventure. And nice use of descriptive detail, by the way. Who taught you that?