The monsoon trough is a portion of the Intertropical Convergence Zone in the Western Pacific,[1][2] as depicted by a line on a weather map showing the locations of minimum sea level pressure,[1] and as such, is a convergence zone between the wind patterns of the southern and northern hemispheres.
Westerly monsoon winds lie in its equatorward portion while easterly trade winds exist poleward of the trough.[3] Right along its axis, heavy rains can be found which usher in the peak of a location's respective rainy season. The monsoon trough plays a role in creating many of the world's rainforests.[4]
The term monsoon trough is most commonly used in monsoonal regions of the Western Pacific such as Asia and Australia. The migration of the ITCZ/monsoon trough into a landmass heralds the beginning of the annual rainy season during summer months. Depressions and tropical cyclones often form in the vicinity of the monsoon trough, with each capable of producing a year's worth of rainfall in a matter of days.