The Coriolis Effect on liquids was
recently debunked by Snopes.
For wind currents; The two turnings of the winds between hemispheres create atmospheric "gears" with the teeth of these gears laying along the equator. The turning of the "gears" keep each other generally moving in opposite directions. Not literal gears, but ones consisting of wind currents rotating around a common barycenter. When two wind currents moving in opposite directions collide at the equator it creates a reaction in accordance with Newtons third law: For every action there is an equal and opposite reaction. The molecules of the air are shot outwards and away with a direction and magnitude directly opposite.
What sits over the equator to make this such a special area? The sun - which constantly imparts temperatures to the two hemispheres, rising pressure directly under its umbrella with its heat, gradually moving the winds within its circling spotlight outwards and away from the high pressures of the day out towards the low pressures of the night. It is analogous to a spoon churning a vast mixing bowl of thick atmosphere. This effect builds up over time, creating predictable and recurring patterns of wind currents.
But this effect is not universal; there are still wind currents which wander into opposing hemispheres, violating the principles of the Coriolis Effect.