1. Waves and Tides

2. Wave Characteristics Most ocean waves are energy passing through water caused by the wind Crests are the top of the waves Troughs are the bottom of the waves Pair Share: How do the water molecules move in a wave? Answer: in a circle

3. Wave Characteristics Wave Height is the vertical distance between trough and crest Wavelength is the horizontal distance between two crests or two troughs Wave period is the time one wave takes to pass a fixed position. Pair Share: How many wavelengths will snowball surf? Answer: 2

4. Factors affecting Waves The height, length, and period of a wave depends of three factors: Wind speed Length of time the wind has blown Fetch, or the distance that the wind has traveled across open water

5. Wave Motion Waves can travel great distances across ocean basins The energy of the wave, not the water itself, travels across the ocean Circular orbital motion allows energy to move through the water, water particles move in circles Energy is moved across the ocean as well as downward

6. Breaking Waves In deep water waves are unaffected by depth In shallow water wave speed slows down causing waves farther out to catch up Speed decrease, wavelength shortens, the wave grows higher When wave is too high to support itself, it collapses Turbulent water created by breaking waves is called surf

7. Tides Tides are regular changes in the elevation of the ocean surface The pull of gravity from the moon and, to a lesser extent by the sun, creates tides Pair Share: Which picture shows high tide? Answer: the bottom one

8. What Causes Tides The difference in the gravitational pull of the moon on the near and far side of the Earth stretches the Earth Inertia is the property of an object that is in motion to stay in motion, and an object at rest to stay at rest. Due to inertia ocean water flows towards both areas - closest and farthest from the moon - creating a tidal bulge Pair Share: What causes the high tides on both sides of the Earth? Answer: Inertia!

9. Tidal Cycle Spring tides are when the sun and moon are aligned, their forces of gravity creates larger tidal bulges Spring tides happen during new and full moons. Neap tides are when the sun and moon are not aligned, their forces off-set each other, creating small tidal bulges Pair Share: Do Spring tides happen only in the Spring? Answer: No they happen twice every month.

10. Tidal Patterns Many factors effect tides, such as shape of the coastline, the ocean basins, and water depth Many factors effect tides, such as shape of the coastline, the ocean basins, and water depth Three main tidal patters: Three main tidal patters: Diurnal tides – single high tide and single low tide each tidal day Diurnal tides – single high tide and single low tide each tidal day Semidiurnal tide – two high tides and two low tides each tidal day Semidiurnal tide – two high tides and two low tides each tidal day Mixed tide – Usually two high and two low tides, however heights are varied. (Our tides here on the Pacific Coast) Mixed tide – Usually two high and two low tides, however heights are varied. (Our tides here on the Pacific Coast)

11. WHITE BOARD REVIEW 1. What is a wave period? 2. How does energy move through a wave? 3. What causes tides?