Chapter Four Prentice Hall Ocean Motions What is the difference between current, wave, and tide? activator Chapter Four Prentice Hall

Wave (the movement of energy through a body of water)- If you have ever seen a video of surfers “catching the perfect wave“ along a Pacific Beach, you know that they make this difficult sport look easy. Biggest wave ever surfed

Where do waves come from Where do waves come from? Most waves form when winds blow across the water’s surface and transmit their energy to the water Waves on the surface of water How waves work animation

Diagram of a Wave-draw and label your own Crest – the highest part of the wave Wavelength – the horizontal distance between crests Frequency- the number of waves that pass a point in a certain amount of time Trough – the lowest part of the wave Wave height – the vertical distance from the crest to the trough

Summarizer View 1st Part of Ocean Motions Waves _____________in the open ocean. The ____________of the wave depends on the ___________of the wind and on the length of ___________ it blows. Although waves _____________________ to carry water toward shore, the water _______________ actually move forward in deep water. The _____________ of the wave is what moves forward. ________________, the wave height increases and the wavelength decreases. When the wave reaches a certain height, the crest __________________over. At first, the energy of the breaking wave, or _____________, cause the water to surge up the beach. But the force of _____________ pulling down on the water causes it to lose its energy.

Summarizer Waves start in the open ocean. The size of the wave depends on the strength of the wind and on the length of time it blows. Although waves may appear to carry water toward shore, the water does not actually move forward in deep water. The energy of the wave is what moves forward. Near shore, the wave height increases and the wavelength decreases. When the wave reaches a certain height, the crest topples over. At first, the energy of the breaking wave, or breaker, cause the water to surge up the beach. But the force of gravity pulling down on the water causes it to lose its energy.

How waves affect the shore Longshore Drift As waves come into shore, water washes up the beach at an angle, carry grains of sand with it. The water and the sand then run straight back down the beach. This movement of sand along the beach is called longshore drift. As the waves slow down, they deposit the sand they are carrying on the shallow underwater slope in a long ridge called a sandbar. Longshore Drift video clip

More Waves Rip Tide Dr. Beach: Rip Currents – YouTube As a sandbar grows, it can trap the water flowing along the shore. In some places, water breaks through the sandbar and begins to flow back down the sloping ocean bottom. This process creates a rip current, a rush of water that flows rapidly back to sea through a narrow opening.

Tsunami - How do they work? Another kind of wave forms far below the ocean’s surface called a tsunami. It is usually caused by an earthquake beneath the ocean floor or can be caused by something big falling into the water, such as a meteorite or landslide. animation Indian Ocean Earthquake and Tsunami

You will learn more about ocean motions In the ppt on tides