Ocean Waves Text Book Page # 358 - 365

Waves A Wave is a rhythmic movement that carries energy through matter or space. In oceans, waves move through seawater. A water wave is the movement of energy through a body of water.

Waves Caused by: Wind Earthquakes

Most waves form when winds blowing across the water’s surface transmit their energy to the water.

Wave size depends on the strength of the wind, and length of the time it blows.

The wave’s energy moves, but the water mostly stays at one place The wave’s energy moves, but the water mostly stays at one place. Individual water molecules move up and down but they do not move forward or backward.

Water Motion As a wave passes, water particles moves in circular motion. Deeper water particles moves in a smaller circles than those near the surface. The wind affects the water at the surface than it affects the deep water. Below a certain depth, the water does not move at all as the wave passes.

Wave Parts Wavelength Crest Wave Height Still Water Trough

Parts of a Wave Crest – The highest point on a wave. Trough – The lowest point on a wave. Wave Height – The vertical distance from the crest of a wave to the trough. Wavelength – The horizontal distance between the crest of one wave and the crest of next wave.

Waves in water 1. In deep water, waves usually travel as long, and low waves called swells.

How waves changes near shore? 2. Friction with the ocean floor causes waves to slow down in the shallow water near the shore. Wavelength decreases

How waves breaks against the shore? 3. When the water reaches certain height, the crest outruns the trough and the crest collapses. 4. The waves breaks onto the shore, forming surf.

Feeling Undertow The water that had rushed up the beach flows back out to sea. This pull is called an undertow carries shells, seaweeds, and sand away from the beach.

Tsunamis are caused by an earthquake beneath the ocean floor.

The abrupt movement of ocean floor sends pulses of energy through water above it.

When tsunami reach the coast, they can be as devastating as an earthquake on land, smashing buildings and bridges.

Longshore Drift and Rip Currents Rip current – A rush of water that flows rapidly back to sea through a narrow opening in a sandbar. Rip current can take a swimmer out into deep water. Longshore Drift – The movement of water and sediment down a beach caused by waves coming in to shore at an angle.

Waves and Beach Erosion - Waves shapes a beach by eroding a shore in some places and building up in others. Barrier Beaches Long sand deposits form parallel to the shore. Separated from the mainland by a shallow lagoon. Natural landform that protects shorelines from wave action occurs along low-lying beaches.

Beach Erosion Sand Dunes – Natural landform Reduces beach erosion Strong roots of dune plants, such as beach grass and sea oats, hold the sand in its place. Groins – A wall made of rocks and concrete that is built outward (perpendicular) from a beach. Reduces beach erosion