Earth’s Oceans

1. Earth’s Oceans

2. Divisions of the Global Ocean • Atlantic second largest • Average depth of 3.6 km • Pacific largest ocean and feature on Earth’s surface • Contains more than ½ of ocean water on Earth • Deepest ocean at 3.9 km • Indian is the 3rd largest • Average depth of 3.8 km • Southern Ocean • Coldest ocean • Arctic Ocean • Sea: smaller parts of ocean partially surrounded by land

3. Earth’s 5 Oceans

4. Properties of Ocean Water • Composition • Salts: carried out by rivers, not returned to land when water evaporates • Elements: chlorine, sodium, magnesium, sulfur, calcium, & potassium • Dissolved gases: Nitrogen, oxygen, & carbon dioxide • Salinity: amount of dissolved salts in ocean water • Increases as temperature increases • Removal (evaporation) of water will increase salinity • Adding of water (rain, rivers) will decrease salinity

5. Properties of Ocean Water 3. Temperature • Surface: temperature effected by sun, moving water underneath, & distance from the equator • Temperature decreases as depth increases • Thermocline: zone of rapid temperature change under surface water

6. Properties of Ocean Water 4. Density: effected by temperature & Salinity 5. As Depth Increases so does the Pressure 6. Color: determined by the way water absorbs or reflects sunlight

7. The movement that carries energy through ocean. Caused by: Wind Tides Earthquakes Volcanic Eruptions Waves

8. Parts of a Wave • Crest – highest point of a wave • Trough – lowest point of a wave • Wave Height – vertical distance between the crest and the trough • Wavelength – horizontal distance between two crests or two troughs

9. Wavelength Crest Wave Height Still Water Trough Wave Parts

10. Wave Movement • When a wave passes through the ocean, individual water molecules move up and down but they do not move forward or backward.

12. Wave Movement • When a wave breaks against the shore, the crest outruns the trough and the crest collapses. • Called a breaker. • In this case, water does move forward and backward.

13. Tides • Caused by the rise and fall of sea level • 4 tides occur daily: 2 high tides & 2 low tides • Tidal Range: Difference between high and low tide • Intertidal Zone: area that high tide covers and low tide exposes • Period when sea level rises: flood tide • Period when sea level falls: ebb tide • Period in between: slack water

15. Sun Tidal influence is only 46% that of the Moon Due to the much greater distance the gravitational force is reduced

16. Ocean Currents • Surface Currents: Currents mainly in the top 100 to 200m of the ocean • Driven by Earth’s wind systems • Northern Hemisphere Trade winds and Westerlies blow the Gulf Stream • Deep currents: Caused by differences in density caused by the temperature and salinity of ocean water • Moves slowly in deep ocean • Cold, dense water sinks at the poles • After sinking these water masses slowly move away from the poles • Eventually return to the surface through upwelling

17. Surface Currents • Upwelling: upward motion of cold water occurs when surface water is moved offshore • Downwelling: warm surface water piles up along the shore and sinks

18. Deep Water Currents • Thermohaline Circulation: ocean conveyer belt • Dominant driving force is difference in density caused by salinity and temperature • As water freezes into ice, the water that does not freeze becomes much more saline. Water that has a high salt content is more dense and as a result will sink. • Cold water is more dense than warm water and will sink