The wind system that had helped early sailors to navigate the earth oceans are trade winds. It is blowing toward the equator from the northern hemisphere or the southern hemisphere. Trade winds are found in the tropics. It strengthens during winter when the Arctic oscillation, is in its warm phase. It has been used by captains of sailing ships to cross the oceans around the world for centuries now. It also acts as the steering flow for tropical storms that form over the major oceans in the world. If the trade winds are weak, then the more rainfall can be expected in the neighboring landmasses.
