What is primarily responsible for the changes in the direction of winds, including the Jet Stream?

The changes in the direction of winds, including the Jet Stream, are primarily influenced by the Coriolis effect. This phenomenon arises due to the rotation of the Earth, which causes moving air and water to turn and twist rather than moving in a straight line. As air moves across the surface of the Earth, the rotation causes it to shift direction based on the hemisphere; in the Northern Hemisphere, for instance, winds are deflected to the right, while in the Southern Hemisphere, they are deflected to the left.

The Jet Stream is a significant upper-atmosphere wind pattern that flows from west to east and is highly influenced by temperature gradients, pressure systems, and the Coriolis effect. As such, this effect is critical in determining the paths that air masses take and thus plays a crucial role in weather patterns.

The other options relate to different aspects of atmospheric and oceanic behavior. Earth's curvature does contribute to wind patterns, but it is not the dominant factor in their deflection. Magnetic fields affect different phenomena, such as compass navigation, but they do not influence wind direction. Ocean currents are driven by wind and can affect weather patterns but do not directly determine the wind direction itself.