A reference frame, or coordinate system fixed on Earth, is not an inertial frame. The Coriolis force affects the rotation of winds around high and low pressure areas in Earth’s atmosphere. Air flows into a low pressure center. The Coriolis force in the northern hemisphere causes all flows to be deflected to the right, creating a counterclockwise flow around the center. In the southern hemisphere the deflection and rotation are in the opposite direction. On the other hand, air flows away from a high-pressure center, and so the deflection causes a clockwise rotation in the northern hemisphere and the opposite in the southern.