U5-Lesson 2: Ocean Waves & Tides

Waves—sound, water, light, earthquake, etc.--are energy passing through a medium (water, air, rock).

•An ocean wave is the movement of energy through a body of water.

•Most waves form when winds blows across the surface of the water transferring their energy to the water.

•Wind speed, duration (length of time wind blows), and fetch (the distance it blows over open water) determine how high a wave grows.

•The highest part of the wave is called the crest.

•Distance from trough to crest is called wave height.

•Distance from crest-to-crest or trough-to-trough is called wave length.

•Lowest part of wave is called the trough.

•Tides are the rise and fall of ocean water that occurs every 12.5 hours. The water will rise for about six hours, then falls about six hours. Tides are mostly caused by the moon’s gravitational pull on the Earth.