Which atmospheric force is created when temperature differences and moisture cause horizontal variations in air pressure?

• A. Wind
• B. Coriolis force
• C. Friction
• D. Pressure gradient force

Answer: (D)

Horizontal pressure differences arise when temperature differences and moisture change air density across the atmosphere. The pressure gradient force is the force that results from those differences, pushing air from regions of high pressure toward regions of low pressure. This force sets air in motion and creates wind. Other factors, like the Coriolis effect (Earth’s rotation) and surface friction, modify the wind once it starts, but the initial driver of horizontal air movement due to pressure variations is the pressure gradient force.