Explanation
- A
Temperature
Option (a) claims that temperature is responsible for wind deflection in the Southern Hemisphere. Temperature differences drive pressure gradients, but they do not directly determine the direction of deflection.
- B
Coriolis force
Option (b) claims that the Coriolis force causes wind to deflect towards the left in the Southern Hemisphere and to the right in the Northern Hemisphere. As the Earth rotates on its axis, it creates an apparent force known as the Coriolis force that deflects moving objects and winds. This Coriolis effect is directly proportional to wind speed and the sine of the latitude, making it the fundamental physical reason for directional wind deflection globally.
- C
Magnetic Field
Option (c) claims that the magnetic field causes wind deflection. The Earth's magnetic field interacts with charged particles in the ionosphere, but it has no mechanical effect on neutral air masses in the troposphere.
- D
Pressure
Option (d) claims that pressure causes wind to deflect towards the left. Pressure gradient force determines the speed and initiation of wind movement from high to low pressure, but rotation and the Coriolis force dictate the curved path.
Summary. Official key is (b) Coriolis force. The rotation of the Earth generates the Coriolis effect, which deflects winds to the left in the Southern Hemisphere and to the right in the Northern Hemisphere. Temperature and pressure establish the movement of air, but the Coriolis force alone dictates the directional curve. Neglecting this rotational component leads to incorrect directional assumptions in meteorology. Thus, option (b) is the correct answer.