Intertropical Convergence Zone

The Intertropical Convergence Zone (ITCZ ITCH, or ICZ), known by sailors as the doldrums or the calms because of its monotonous windless weather, is the area where the northeast and the southeast trade winds converge. It encircles Earth near the thermal equator, though its specific position varies seasonally.

Source: Wikipedia — Intertropical Convergence Zone (CC BY-SA 4.0)