easterly wave A type of weak trough in a tropical easterly airflow, which has a wavelength generally of 2000–4000 km. Such waves occur, for example, over West Africa and in the Caribbean area, where they develop in summer and autumn with a weak or absent trade-wind inversion, and in the central Pacific, when the equatorial trough is displaced northwards. Disturbances in such waves often lead to tropical storms, which vary in intensity.

easterly wave Type of weak trough in a tropical easterly airflow, which has a wavelength generally of 2000–4000 km. Such waves occur, for example, over W. Africa and in the Caribbean area where they develop in summer and autumn with a weak or absent trade-wind inversion, and in the central Pacific, when the equatorial trough is displaced northward. Disturbances in such waves often lead to tropical storms, which vary in intensity.