Crossing the equator

On the 1st of April, the Sarmiento de Gamboa crossed the equator and reached the waters of the northern hemisphere after 14 days at sea. The equator is an imaginary line which marks the demarcation between the two hemispheres. Though this line is obviously not visible in nature, its crossing can be felt and experienced in different ways.

First of all, the heat. As the equator approached, the air grew warmer and humidity raised by the day, as did the sea surface temperature, which exceeded 29 degrees on certain days. Tropical and equatorial areas are particularly concerned by the increase of average surface temperature. This threatens marine life in general, leads to species' migration and disturbs the species composition and equilibrium of marine ecosystems.

Typical sky when crossing the doldrums.

The passage of the equator was also marked by the passage of the zone that sailors call the “doldrums”. Also called the Intertropical Convergence Zone (ITCZ), it is the area where the northeast and the southeast trade winds converge. Indeed, this zone receives the highest amount of solar energy and has the highest rates of evaporation. It is this evaporation that causes air to be drawn in, resulting in the convergence of winds. The weather associated is very erratic and involves the formation of numerous showers and thunderstorms. The winds are often calm, but with the potential to become powerful so close to the thunderstorms. This can be hazardous for sailing ships but, in our case, we were rather happy to encounter a bit of tropical rain after days of blazing sun.

Weather model showing the boat (white circle) in the middle of heavy rainfall (in green/yellow) in the intertropical convergence zone during station 6. The convergence of south and north winds is clearly visible.

Last but not least, scientists, technicians and sailors who had never before crossed the equator have had to face up to the ritual of Neptune, a tradition from which no one on board can escape. But we'll say no more about it here. Rest assured; the whole team emerged unharmed, ready for the rest of the voyage in the northern hemisphere.

Celebrating the equator crossing.