Trade winds Fontaine Maury collected enough information to create wind and current charts for the world's oceans. As part of the Hadley cell, surface air flows toward the equator while the flow aloft is towards the poles. A low-pressure area of calm, light variable winds near the equator is known as the doldrums, near-equatorial trough, intertropical front, or the Intertropical Convergence Zone. When located within a monsoon region, this zone of low pressure and wind convergence is also known as the monsoon trough. Around 30° in both hemispheres, air begins to descend toward the surface in subtropical high-pressure belts known as subtropical
Intertropical Convergence Zone of wind change and speed, otherwise known as horizontal wind shear. As the ITCZ migrates to tropical - subtropical latitudes and even beyond (Shandong province of the People's Republic of China) during the respective hemisphere's summer season, increasing Coriolis force makes the formation of tropical cyclones within this zone more possible. Surges of higher pressure from high latitudes can enhance tropical disturbances along its axis. In the north Atlantic and the northeastern Pacific oceans, tropical waves move along the axis of the ITCZ causing an increase in thunderstorm activity, and under weak vertical wind shear, these clusters of thunderstorms can