The Intertropical Convergence Zone or ITCZ is an area near the equator where the southeasterly breezes that are predominant in the Southern Hemisphere collide with the Northern Hemisphere's northeasterlies. When the two wind patterns collide, they produce an area of unstable weather, characterized by violent squalls, followed by periods of calm.
ITCZ is a relatively modern term for an ancient phenomenon. Seamen used to refer to this region of unstable weather and light winds as the doldrums. Before ships had engines they could be trapped in the doldrums for days or weeks, waiting for a breath of wind to fill their sails. Luckily, we have an engine, and plenty of diesel to power through the calms if need be.
The ITCZ moves around constantly. The yachts that left St. Helena a few days before we arrived had the bad luck to have it pass back and forth over them several times as they made their way north. We've been tracking the movements of the ITCZ via daily Met.5 forecasts that we download through Sailmail. It is currently 3/4 of a degree wide (about 45 miles) and has been hovering between 2 and 4 degrees north of the equator. We're hoping that it says put for the next week. It will be a few more days before we cross the equator and then we should have another day or two of smooth sailing before we have to start working for our miles in the ITCZ. Once we pass through it, we'll be squarely in the northeasterlies, making fast miles for Barbados.