Which term defines wind?

• A. The boundary between two air masses
• B. The rotation of the Earth
• C. The horizontal or vertical movement of air over the Earth
• D. The movement of water in the ocean

Answer: (C)

Wind is the horizontal or vertical movement of air over the Earth. This air motion arises from pressure differences in the atmosphere, with air moving from high to low pressure and varying with height and temperature. In navigation and ship handling, wind is described by its speed and direction at a reference height, since that’s what drives vessel movement and performance. The boundary between two air masses describes a weather front, not wind itself. The rotation of the Earth leads to the Coriolis effect, which curves wind paths on large scales but does not define wind. Movement of water in the ocean refers to currents, not atmospheric wind. So the defining idea is the movement of air relative to the Earth’s surface.