The trade winds are winds that reliably blow east to west just north and south of the equator.
There is a more or less regular inflow of winds from subtropical high-pressure belts to equatorial low-pressure belts.
These tropical winds have a north-easterly direction in the northern hemisphere while they are south-easterly in the southern hemisphere.
The poleward parts of trade winds or eastern sides of the subtropical anticyclones are dry because of strong subsidence of air currents from above because of the dominance of anticyclonic conditions there is strong atmospheric stability, strong inversion of temperature, and clear sky.
On the other hand, the equatorward parts of the trade winds are humid because they are characterized by atmospheric instability and much precipitation as the trade while blowing over the oceans pick up moisture.
It may be noted that trade winds are more regular and constant over the oceans than over the lands.
Rajnish
Trade Winds: