Tuesday, 23 July 2013

Mid-Atlantic – Half Way

Tuesday 23rd July, 6pm, 45N, 41W.

Sometime this afternoon we passed the halfway point on this voyage across the Atlantic Ocean.  I’ve now presented the first two of my four lectures, with a full house for the second one on alien life, and am preparing for tomorrows lecture about impact events.  The weather had been overcast and exceptionally windy for the past couple of days, and I went out onto the Deck 7 promenade sparingly, to blow the cobwebs away.  We’re now over 1500 miles from both our embarkation and destination points.  Today the sea has calmed, the sun is shining, and dolphins have once again been spotted off the side.  Since Monday noon, we have moved from 49N, 25W to 45N, 41W following the great circle path from Southampton to New York.  We’ve crossed three time zones already, and have passed points in the Atlantic with 4500 m of water beneath our keel.  Now we’re headed for the Grand Banks off Newfoundland, passing just to the north of a feature called the Flemish Cap, a region of 102-m depths compared to the ocean floor 3500-m deep.  The Grand Banks themselves are the start of the North American continental shelf, with the depth shallowing to 60-m in places. 

This region of the Atlantic is governed by conflicting ocean currents:  the warm Gulf Stream and its extension to northern Europe (the North Atlantic Drift) forming the eastward flowing northern edge of an Atlantic Gyre, which closes by flowing south along the Canary coast of Africa before heading west again in the North Equatorial Current.  These four currents form the ‘Columbus Gyre’ in the northern Atlantic, and the Gulf Stream is responsible for transportation of warm water to make northwest Europe more temperate than it would be otherwise.  In addition, the Labrador Current flowing south from Greenland brings cold, moist air and the infamous fogs of the Grand Banks.  This current, along with the Norwegian and East Greenland Current form the ‘Viking Gyre’, sitting further north and conflicting with the ‘Columbus Gyre’.  So the good weather may not be here to stay for the second half of our journey!

1479 nautical miles to go.....

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