1. 14.1 INTRODUCTION TO THE OCEANS Hydrosphere

2. Learning Targets 1.Explain the significance of the oceans 2.Describe the composition of ocean water 3.Define the parts of the water column and oceanic divisions.

3. Significance of the Oceans 1.Regulates climate a)Distributes heat around the planet 2.Affect composition of atmosphere a)Absorbs and releases water, oxygen, carbon dioxide, etc. 3.Home to millions of species 4.Formed ~4 billion years ago by: a)Volcanic outgassing b)Meteor and comet impacts

4. Composition of Ocean Water Where does the salt in the oceans come from? Salt in the ocean comes from dissolved minerals in rocks carried by streams and rivers. Water that contains: 1.More salt = more dense  sink 2.Less salt = less dense  float

5. Composition of Ocean Water What could cause salinity (salt content) levels to change at different locations around the world? 1.Increase evaporation  increase salinity 2.Estuary  decrease salinity

6. Composition of Ocean Water Water density increases as: 1.Salinity increases 2.Temperature decreases with depth a)Colder temperatures decreases the amount of volume, but not mass 3.Pressure increases with depth

7. Composition of Ocean Water Why do we care about water density? Differences in water density are responsible for deep ocean currents.

8. Water Column Scientists define the water column by depth: 1.Photic zone – sunlight reaches a)Top 200 meters 2.Aphotic zone – no photosynthesis

10. Water Column What 3 factors make the deep ocean hard to inhabit? 1.Absence of light 2.Low temperature 3.Extremely high pressure

11. Divisions of the Ocean Scientists also define the water column horizontally by distance from the shore: 1.Intertidal a)Between high and low tide 2.Neritic a)Shallow area with gentle slope 3.Oceanic a)Beyond neritic zone; very deep