Eureka HN B 0 on Instagram: "At the equator, the Coriolis force is zero because the horizontal component of Earth's rotational velocity is perpendicular to the local vertical. As a result, there is no net rotational deflection for freely falling or draining water. North or south of the equator, the Coriolis effect introduces a small horizontal force that deflects moving fluids rightward in the Northern Hemisphere and leftward in the Southern Hemisphere producing opposite rotation senses in princ