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Variable Southeasterlies and Southerly winds sailing over a ridge of High Pressure

A day of variable Southerly winds, a journey surrounded by squalls and showers. 

Southeasterlies blow and ease, increase and calm. Then they turn to Southerlies and even for a while, with the passing of low clouds and squalls even come to an unexpected westerly, then die down, making for steering more to the north until it all comes back to Southerlies again. All in all the general steering is due west. 

Variable and unstable weather after the steady sailing downwind from yesterday, when three of our Studding sails were catching the breeze helping the rest of the sails to keep a speed of about 5kn. 

They had to be stowed away last night when the wind turned already to more southerly than the light blows from the east. A swift operation made for bringing them on deck before bracing sharper, adapting sails and braces to this wind. The light and old canvas of the lower one ripped in our hands as doing so. During the daylight was the time to stitch it again and have it ready once more for when it will be of any use aloft. Though not for now. The changes in the wind we are experiencing are related to the development of a High-Pressure Ridge extending in a northeasterly direction from the large High southwest of us. A developing meander on its isobars that made for the easterlies on the top of it to curve and bring us the fair winds from a southerly quarter that we are sailing now. A situation that looks like it's extending for five or six hundred miles before we go over this ridge and catch again the easterlies. 

A curl of higher pressure flanked by relatively lower ones, combined with the high water temperature and evaporation makes for unstable weather, passing squalls and cloudy skies. 

Now braced sharp on Port tack, now Beam reach, then squarer, afterward again sharper, adapting to the wind shifts and passing showers we have sailed 110nm in the last 24 hours, a distance that positions us 1086nm from Easter Island at just about the change of watch at 20:00h 

Afterwards, a calm night of steady good breeze started with a bit of bracing to Beam reach. Once the rope pulling and sail adjusting are done, quick light flashes when looking at the waters at our wake under the bow surprising some of us.  

On still warm nights, especially in tropical and subtropical areas, moving boats sometimes leave a glittering trail where the water surface is being disturbed as the ship cuts through it. A beautiful phenomenon caused by bioluminescent plankton, jellyfish, squid, and some deep-water fish. In these open surface waters, the little light flashes that we can see are most frequently produced by the unicellular dinoflagellates. Millions of them can twinkle in the waves with a blue-green light generated by a chemical reaction and emitted from small organelles within the cells. These Dinoflagellates may use bioluminescence for defense. They shine when they detect a disturbance in the water produced by a possible predator, making it more vulnerable by attracting the attention of predators from higher trophic levels.  

There can be other several reasons for an organism to produce this bioluminescence, like warning, communication, mate attraction, startle, camouflage by counter illumination, misdirection, and distractive strategies. 

Written by:
Jordi Plana Morales | Expedition Leader

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