Ocean currents and waves are influenced by several factors. Countercurrents flow in the opposite direction of surface currents to fill voids where surface water has moved. Waves are formed based on wind speed, duration, and the expanse of open water. Wave size and type is also affected by these conditions, creating choppy, white-capped, or swelling waves. Upon reaching shallow water, waves can break and create surf that moves up the beach. Currents like undertow and rip currents also influence nearshore ocean water movement and transport water back out to sea. Tides are predictable ocean currents caused by the moon's gravity, resulting in high and low tides depending on its positioning.

1. 9 th Grade Chapter 4 Lesson 2 Pgs. 92-96 For Student Use Only

2. Ocean Currents Countercurrents: When surface currents flow other places water from other places rushes in to meet the currents. Countercurrent- the current filling the void when surface water moves away. Countercurrents can exist on the surface or in a subsurface area

3. Ocean Currents http://www.dorlingkindersley-uk.co.uk/nf/ClipArt/Thumbnail/0,,239020,00.html

4. Ocean Currents Waves and Related Phenomena Waves: Rhythmic movement of water back and forth that transfer energy Wave Parts Crest- high point Trough- low point Period- time between waves

5. Ocean Currents Wave Formation: Three main factors determine the size of these waves: Speed of the wind The length of time wind blows The expanse of open water over which the wind blows

6. Ocean Currents Waves: Choppy- gusty winds cause waves that are different sizes in different sizes and directions White Caps: strong winds that whip waves into a spray with a foamy crest Ocean Swells: gentle rolling waves

7. Ocean Currents Wave Motion Water only moves a few feet, energy moves to shore Breaker: Water moves quicker at top and slower at bottom when water is shallow, the then topples over itself Surf: Foaming water that goes up the beach

8. Ocean Currents Currents: Undertow- Small stream of water that is going from shore back to sea Longshore current- When there is a sandbar and water that flows parallel to the beach Rip Current (Rip Tide)- surface current that carries large amounts of water back to sea through incoming breakers

9. Ocean Currents Waves: Tsunamis- gigantic waves that are caused by earthquakes, volcanic explosion, or undersea landslides. These waves can be 200 ft. tall as they build up closer to shore.

10. Ocean Currents Tides: Predictable currents Caused by the moon’s gravity High Tide- moon’s gravity is strongest Low Tide- side not experiencing moon’s gravity Spring Tide- sun and moon team up to pull the water Neap Tide- weak tides- moon and sun at 90 degree angles