A line (or transition zone) that encircles the earth and lies between two belts that typify the annual time distribution of rainfall in the lower latitudes of each hemisphere; a form of meteorological equator. It lies slightly north of the geographic equator, reaching its most northerly position at about 10°N latitude near the mouth of the Orinoco River in South America. The hyetal equator is more or less centrally situated in the belt of tropical rainfall, which has two rainy seasons and generally one main dry season, the latter occurring in the winter of the corresponding hemisphere.