1. Properties of Ocean Water Chapter 17

2. How do we learn about the ocean floor? Echo sounding – sound waves are sent down from a ship, hit the ocean floor, and return to the ship Measure the time it takes for a round trip and you can calculate the depth

3. Sound travels at 1500 meters per second Watch out for round trip times!

4. How do we learn about the ocean floor? Direct Observation Mini-submarines like Alvin Drawback – too much time going up and down

5. Origin of the Oceans 1.Many Volcanoes Erupted. 2.They released gases, including water vapor. 3.The vapor condensed into liquid water. 4.The water rained from the sky and collected in large basins, forming the oceans.

6. Ocean Formation Water Condenses Water vapor released Rain

7. Salinity Dissolved salts give ocean water a property called salinity.

8. Salinity High salinity occurs: In regions of high evaporation In regions of low rainfall Low salinity occurs: Where rivers flow into oceans (Estuaries) In regions of high rainfall In regions with melting ice

9. Temperature Only the top of the ocean is directly warmed by the sun. (Mixed Layer) Downward to a depth of 300 m.

10. Temperature Just below this surface zone, the water temperature changes rapidly. This zone of rapid change is called a thermocline.

11. Temperature Below a thermocline, most of the water is about the same cold temperature This layer is called the “Bottom Layer”

12. Density High-salinity water is more dense than low- salinity water. Why? Salt is heavy Cold water is more dense than warm water. Why? Molecules are closer together