|"Trade winds" are the persistent, mostly-easterly, flow of the near-surface winds
over the tropical oceans. This persistent flow is the result of huge, semi-permanent
high pressure zones that exist over the tropical
and subtropical oceans. These high pressure zones are partly caused by the relatively cool
ocean water (compared to the warm land air masses), especially over the eastern half of the
ocean basins. The trade winds are only interrupted by the passage of tropical cyclones,
or an occasional cold front arriving from higher latitudes.