Trade wind are due to __________.
Trade winds are result of combination of both convection of air currents and rotation of earth.
Due to warmer air at equator the process of convection takes place where heat is transferred to the lower heat areas from higher heat areas.
Thus warmer winds are moved towards the each pole respectively from equator and due to rotation of earth these winds fall back to the equator.
These winds blow nearly constantly and always in the same direction. The trade winds have been used for many centuries to decrease the transit time of ships traveling around the world.