1. Chapter 3 Part II

2. Ocean Circulation  The ocean is always moving.  This circulation affects marine organisms, their habitats, and the earth’s climate.  The earth’s climate in turn affects all habitats on land.  The ocean is always moving.  This circulation affects marine organisms, their habitats, and the earth’s climate.  The earth’s climate in turn affects all habitats on land.

3. Surface Circulation  The most intense ocean currents are found at the surface.  Both surface currents and the wind are strongly influenced by what is known as the Coriolis effect.  The most intense ocean currents are found at the surface.  Both surface currents and the wind are strongly influenced by what is known as the Coriolis effect.

4. Coriolis Effect  The tendency of objects moving large distances on the earth’s surface to bend to the right in the Northern Hemisphere and the left in the Southern Hemisphere.  In the Northern Hemisphere- winds and ocean currents move to the right.  In the Southern Hemisphere- winds and ocean currents move to the left.  The tendency of objects moving large distances on the earth’s surface to bend to the right in the Northern Hemisphere and the left in the Southern Hemisphere.  In the Northern Hemisphere- winds and ocean currents move to the right.  In the Southern Hemisphere- winds and ocean currents move to the left.

5. Wind Patterns  Winds in our atmosphere are driven by the thermal energy from the sun.  Warmer air rises because it is less dense. Therefore Equatorial air rises and sucks in air from adjacent areas to replace this equatorial air, creating wind.  Winds in our atmosphere are driven by the thermal energy from the sun.  Warmer air rises because it is less dense. Therefore Equatorial air rises and sucks in air from adjacent areas to replace this equatorial air, creating wind.

6. Trade Winds  Steady winds that blow from east to west toward the Equator, replacing the hot air that rises at the Equator.

7. Other Winds  Westerlies- found at the middle latitudes and move opposite to the trade winds.  Polar easterlies- most variable of all winds found at high latitudes.  Westerlies- found at the middle latitudes and move opposite to the trade winds.  Polar easterlies- most variable of all winds found at high latitudes.

8. Surface Currents  Are formed by major wind fields pushing the sea surface.  The uppermost layer of surface water beings to move when pushed by the wind.  These currents move off the ocean surface at a 45 degree angle because of the Coriolis effect.  Are formed by major wind fields pushing the sea surface.  The uppermost layer of surface water beings to move when pushed by the wind.  These currents move off the ocean surface at a 45 degree angle because of the Coriolis effect.

9. Ekman spiral  The spiral change in the movement of water in the water column when the water is pushed by the wind.  The Ekman layer- the part of the water column affected by the wind.  Ekman transport- net movement of water 90 degrees from wind direction.  The spiral change in the movement of water in the water column when the water is pushed by the wind.  The Ekman layer- the part of the water column affected by the wind.  Ekman transport- net movement of water 90 degrees from wind direction.

10. Equatorial Currents  Major ocean currents that move parallel to the equator.

11. Gyres  Huge, less circular systems that are under the influence of the Coriolis effect.  These are wind-driven surface currents.  Fig. 3.18  Fig. 3.19  Fig. 3.20  Huge, less circular systems that are under the influence of the Coriolis effect.  These are wind-driven surface currents.  Fig. 3.18  Fig. 3.19  Fig. 3.20

12. Role of Surface Currents  The role of surface currents in transporting heat is reflected in the temperature of the sea surface.  Surface temperature is always higher on the western sides of the oceans.  Because of this, tropical organisms like corals tend to extend into high latitudes on the west sides of oceans.  Fig. 3.21  The role of surface currents in transporting heat is reflected in the temperature of the sea surface.  Surface temperature is always higher on the western sides of the oceans.  Because of this, tropical organisms like corals tend to extend into high latitudes on the west sides of oceans.  Fig. 3.21

13. Thermohaline Circulation  Ocean circulation that is driven by differences in water density, due to variations in water temperature and salinity, rather than by the wind or tides.

14. The Three-Layered Ocean  Surface Layer- Usually around 100- 200m (330-660 ft) thick.  Much of time this layer is mixed by wind, waves, and currents.  It is also known as the Mixed Layer.  Surface Layer- Usually around 100- 200m (330-660 ft) thick.  Much of time this layer is mixed by wind, waves, and currents.  It is also known as the Mixed Layer.

15. Thermocline  Sudden changes in water temperature over small depth intervals.  Ex: During spring and summer in polar water, the uppermost water gets heated by the sun. This warm water floats on top. There is a sharp transition between this water and the water below.  Sudden changes in water temperature over small depth intervals.  Ex: During spring and summer in polar water, the uppermost water gets heated by the sun. This warm water floats on top. There is a sharp transition between this water and the water below.

16. Intermediate Layer  Lies below the surface layer.  Typically at a depth of 1000-1500m (3300-5000ft).  The Main Thermocline, a zone of transition between warm surface water and cold water below is in this layer.  Lies below the surface layer.  Typically at a depth of 1000-1500m (3300-5000ft).  The Main Thermocline, a zone of transition between warm surface water and cold water below is in this layer.

17. Deep and Bottom Layers  Below about 1500m (5000ft).  Typically cold at less than 4C or 39F.  Below about 1500m (5000ft).  Typically cold at less than 4C or 39F.

18. Water Column Stability  Most of the time surface water is warm and less dense and floats on top unless it is acted upon by wind or wave energy.  This is referred to as a Stable water column.  Most of the time surface water is warm and less dense and floats on top unless it is acted upon by wind or wave energy.  This is referred to as a Stable water column.

19. Water Column Instability  Caused by downwelling.  Downwelling occurs when surface water sinks and displaces and mixes with deeper water.  This process is known as overturn.  Caused by downwelling.  Downwelling occurs when surface water sinks and displaces and mixes with deeper water.  This process is known as overturn.

20.  Because surface water all with the same temperature and density descends through the water column, the temperature and density profiles are vertical straight lines.  Overturn usually occurs in temperate and polar regions during the winter when surface water cools.  Because surface water all with the same temperature and density descends through the water column, the temperature and density profiles are vertical straight lines.  Overturn usually occurs in temperate and polar regions during the winter when surface water cools.

21.  Oceanographers use this overturn to follow the movement or circulation of water masses over great distances.  Fig. 3.24  Oceanographers use this overturn to follow the movement or circulation of water masses over great distances.  Fig. 3.24

22. The Great Ocean Conveyor  The global thermohaline circulation that mixes the oceans every 4000 years.  It is critical in regulating the earth’s climate.  It brings dissolved oxygen to the deep. This effect is enhanced because oxygen dissolves best in cold water.  The global thermohaline circulation that mixes the oceans every 4000 years.  It is critical in regulating the earth’s climate.  It brings dissolved oxygen to the deep. This effect is enhanced because oxygen dissolves best in cold water.

23. Waves and Tides  Waves- Undulations that form as a disturbance moves along the surface of the water.

24. Parts of a Wave  Crest- highest part of a wave.  Trough- lowest part of a wave.  Wave height- size of an ocean wave. Measured by the vertical distance between the trough and the crest.  Wavelength- the distances between crests or troughs.  Crest- highest part of a wave.  Trough- lowest part of a wave.  Wave height- size of an ocean wave. Measured by the vertical distance between the trough and the crest.  Wavelength- the distances between crests or troughs.

25. Period  Time it takes a wave to go by any given point. Did you know? That particles under a wave don’t go anywhere as a wave passes, they just move in a circular motion.  Time it takes a wave to go by any given point. Did you know? That particles under a wave don’t go anywhere as a wave passes, they just move in a circular motion.

26. Wave size and Wind Speed  Waves begin to form as soon as the wind starts to blow.  The faster and longer the wind blows the larger the waves get.  Fetch- the span of open water over which the wind blows also determines the size of a wave.  Waves begin to form as soon as the wind starts to blow.  The faster and longer the wind blows the larger the waves get.  Fetch- the span of open water over which the wind blows also determines the size of a wave.

27. Types of Waves  Seas- Waves that have a sharp peak and relatively flat trough. Are found in areas where waves are generated by wind.  Swells- A wave with a flatter, rounded wave crest and trough. Are found away from the area where waves are generated by the wind.  Seas- Waves that have a sharp peak and relatively flat trough. Are found in areas where waves are generated by wind.  Swells- A wave with a flatter, rounded wave crest and trough. Are found away from the area where waves are generated by the wind.

28. Surf  Waves that become so high and steep as it approaches the shoreline that it breaks.  Wave reinforcement- when the crests of two waves collide and add together producing a wave that can seem to come from nowhere and can be as tall as a ten-story building.  Waves that become so high and steep as it approaches the shoreline that it breaks.  Wave reinforcement- when the crests of two waves collide and add together producing a wave that can seem to come from nowhere and can be as tall as a ten-story building.

29. Tides  The periodic, rhythmic rise and fall of the sea surface.  Tides are caused by the gravitational pull of the moon and sun and by the rotations of the earth, moon, and sun.  The periodic, rhythmic rise and fall of the sea surface.  Tides are caused by the gravitational pull of the moon and sun and by the rotations of the earth, moon, and sun.

30. How are tides formed?  The moon’s gravity is strongest on the side of the earth closest to the moon.  Here the moon’s gravity pulls wate in the ocean toward the moon.  On the opposite side of the earth the ocean bulges away from the moon due to centrifugal force.  Fig. 3.32  The moon’s gravity is strongest on the side of the earth closest to the moon.  Here the moon’s gravity pulls wate in the ocean toward the moon.  On the opposite side of the earth the ocean bulges away from the moon due to centrifugal force.  Fig. 3.32

31. High Tides  Occurs when a given point on the earth is under a bulge.  Because it takes the earth 24 hours to complete a rotation, this point will have two high tides and two low tides every day.  A full tidal cycle takes 24 hours and 50 minutes.  Occurs when a given point on the earth is under a bulge.  Because it takes the earth 24 hours to complete a rotation, this point will have two high tides and two low tides every day.  A full tidal cycle takes 24 hours and 50 minutes.

32. The sun’s effect on the tides.  The sun produces tidal bulges, but in a much smaller scale than the moon.  When the sun and moon are in line with each other at the full and new moons their effects on the tide are added together.  The sun produces tidal bulges, but in a much smaller scale than the moon.  When the sun and moon are in line with each other at the full and new moons their effects on the tide are added together.

33.  Tidal range- difference in water level between successive high and low tides.  Spring tides- Tides with a large tidal range. They occur around the time of the full and new moon.  Neap tides-Tides with at small tidal range. They occur around times when the moon is in quarter.  Tidal range- difference in water level between successive high and low tides.  Spring tides- Tides with a large tidal range. They occur around the time of the full and new moon.  Neap tides-Tides with at small tidal range. They occur around times when the moon is in quarter.

34.  Semidiurnal tides- when an area has two high tides and two low tides a day.  Ex: East Coast of North America, most of Europe and Africa.  Mixed semidiurnal tides- areas with successive high tides of different height.  Ex: West Coast of North America, and Canada  Diurnal tides- areas with one high and low tide a day.  Uncommon-but occur in Antarctica, part of the Gulf of Mexico, Caribbean, and Pacific.  Semidiurnal tides- when an area has two high tides and two low tides a day.  Ex: East Coast of North America, most of Europe and Africa.  Mixed semidiurnal tides- areas with successive high tides of different height.  Ex: West Coast of North America, and Canada  Diurnal tides- areas with one high and low tide a day.  Uncommon-but occur in Antarctica, part of the Gulf of Mexico, Caribbean, and Pacific.

35. Tide Tables  Give the predicted time and height of high and low tides in coastal areas.