Which term describes the regular rise and fall of the ocean's surface influenced by the moon's gravity pulling on earth?

• A. Currents
• B. Waves
• C. Winds
• D. Tides

Answer: (D)

Tides describe the regular rise and fall of the ocean surface caused by the Moon's gravity pulling on Earth. The Moon’s gravity creates bulges in the ocean—one on the side closest to the Moon and one on the opposite side—so as Earth rotates, different areas experience high tides as they pass under those bulges and then low tides as they move away. The Sun also influences tides, but the Moon has the stronger effect. This is different from waves, which are generated mainly by wind transferring energy to the water, or from currents, which are horizontal movements of water. So the term that matches the described phenomenon is tides. For context, tides can be higher during full or new moons (spring tides) and lower during quarter moons (neap tides).