Log - July-13-2003 by Andreas Müchow Previous | Next Expedition Expedition | People Crossing the Gulfstream All sensors went wild today as we approached the northern extension of the Gulfstream. After sailing for 4 days in warm and salty tropical and sub-tropical waters, we experienced a drop in surface temperature and surface salinity. And the resulting ocean outside looks like this right now : FOG. The fog is caused by warm offshore air moving over water that is much cooler. The water cools the air, changes its dew point, and little water droplets form (the fog). Frontal regions in the ocean almost always do this and we will see many more examples of this as we enter the Arctic. The thermo-salinograph of the Healy records temperature and salinity every few seconds. The plot shows the temperature and salinity data as it changed yesterday and today (July-14). At the beginning of the day temperature and salinity are fairly constant, about 27 degrees Celsius (~88F?) and ~36 practical salinity units (psu) as we sailed along a straight line north. This all changed rapidly as the water cooled to ~22C (~75F) and the salinity droped to a dramatically to near 32psu. At first I thought there was a problem with the sensors as this type of water usually sits on the shelf of the Mid-Atlantic Bight and does not extend as far out as where we are.