Correct Option
The rotation of the Earth is the fundamental cause of wind deflection in the Southern Hemisphere. This phenomenon is explained by the Coriolis force, an apparent force that acts on moving objects within a rotating frame of reference, such as the Earth. Due to the Earth's rotation from west to east, the Coriolis force deflects moving air (wind) to the left of its direction of motion in the Southern Hemisphere. This force is absent at the equator and increases towards the poles, significantly influencing global wind patterns, ocean currents, and the rotational direction of weather systems like cyclones.
Incorrect Options
(a) Temperature: Temperature differences create pressure gradients, which are the primary drivers for the generation and initial movement of wind. However, temperature itself does not directly cause the deflection of wind from its path.
(b) Magnetic field: The Earth's magnetic field primarily interacts with charged particles, such as those found in solar wind or the ionosphere. It does not exert a significant force on the neutral gas molecules that constitute atmospheric winds, and therefore, does not cause their deflection.
(d) Pressure: Pressure differences are responsible for initiating wind movement, as air flows from areas of high pressure to areas of low pressure. While pressure gradients determine the initial direction and speed of wind, they do not cause the subsequent deflection of wind to the left or right; that effect is solely due to the Earth's rotation.