noun
doldrums; equatorial calms
Meteorological term for the low-pressure zone near the equator with light, variable winds. Often used in nautical and climate contexts.
帆船は赤道無風帯に入って、何日も進めなかった。
The sailing ship entered the doldrums and couldn't make headway for days.
赤道無
The doldrums are also called the Intertropical Convergence Zone.