Bom dia !

We are using the waiting time to study the weather charts and plot our navigation, using known currents and local weather conditions in our advantage. One of the challenges between João Pessoa and Trinidad will be the "ITCZ", or the Inter-tropical Convergence Zone.

The phenomenon is basically due to solar radiation warming the air over the equator, causing it to rise. The rising air moves towards the poles, both North and South. When the air reaches between 20 and 30 degrees North and South latitude the air starts sinking again and flows along the surface of the earth back to the equator.

The effect is that usually between 5 degrees, both North and South of the equator there is a zone where the wind isn't blowing.....not exactly what we want on a sailing boat. The zone is called "the Doldrums" by sailors. The air in the doldrums is rising without producing wind, and at the equator this means a really "hot" region. I hope the fridge will work to provide us a cool drink.

The ITCZ is not stationary but rather moves North and South of the equator, depending on the amount of solar energy received, solar radiation is therefore different between winter and summer. According to my research the variation can be as much as 40 to 45 degrees North and South of the equator (based on a pattern of land or ocean). Fortunately with today's technology we can go on the Internet and check the location of the ITCZ for the trip.

It all seems a bit boring, but the truth is that we could be shaken violently out of our sleeping doldrums. The danger is not the lack of wind, as we can always motor through those windless zones, but rather the convectional storms created by the convergence of North and South trade winds within the ITCZ. The precipitations are known to be amongst the most violent in the world in this region. That will keep us awake I think.

Another challenge ahead.....but that is what it's all about !

Marc