2. The World’s Oceans
71% of the Earth’s surface is covered by ocean water.
The oceans contain 97% of the earth’s water.
All the oceans and seas are actually one continuous body of water.

3. Oceans
The oceans are the Atlantic, Pacific, Indian. Arctic and Southern.
The Pacific Ocean is the largest ocean.
The area and volume of the Pacific Ocean are greater than the Atlantic and Indian combined.

4. Water Cycle The sun’s rays heat the surface of the ocean.
The heat causes the water to evaporate.
The evaporating water (clean, fresh water) enters the atmosphere as water vapor.
The salt remains behind.

5. Water Cycle The water cycle always starts with a heat source.
Some of the water vapor condenses to form clouds.
The water in the clouds falls as precipitation.

6. Water Cycle
Some of this water runs into rivers and streams which flow back into the oceans.
Some of the water seeps into the soil and rocks become part of the groundwater.

7. Properties of Ocean Water
Ocean water is a mixture of gases and solids dissolved in pure water.
Oceanographers believe oceans contain all the natural elements on Earth.
85 of 90 elements have been found in the ocean.

8. Major Elements in the Ocean
Ocean water is 96% pure water.
Chlorine (1.9) and sodium (1.1) make up the next largest concentration of elements.
Sodium chloride is table salt.

9. Salinity
Salinity describes the amount of dissolved water in the ocean.

10. Sources of Salt in the Ocean
When volcanoes erupt, rock materials and gases, such as chlorine, spew forth.
As rivers, streams and glaciers move over rock and soil, they dissolve salts, such as magnesium, sodium and potassium, in them.

11. The Ocean Floor
The topography (what land features look like) of the ocean floor is different from the topography of the continents

12. The Ocean Floor
The ocean floor has higher mountains, deeper canyons, and larger flatter plains. Earthquakes occur more often.
The crust is thinner.

13. Edges of the Continents
The shoreline is a boundary between where the land and the ocean meet.
The area where the underwater edge meets of a continent meets the ocean floor is called a continental margin.

14. Continental Shelf
The flat part of a continental margin that is covered by shallow ocean water is called a continental shelf.
A continental shelf slopes gently from the shoreline.
Large mineral, oil and natural gas deposits are found here.

15. Continental Slope
At the edge of the continental shelf, the ocean floor plunges steeply 4 to 5 kilometers.
A continental slope marks the boundary between the crust of the continent and the crust of the ocean floor.

16. Abyssal Plains
Large, flat areas on the ocean floor are called abyssal plains.

17. Seamounts and Guyots
Seamounts are underwater volcanic mountains that rise more than 100 meters above the ocean floor.
Guyots are flat-topped seamounts.

18. Trenches
Trenches are the deepest parts of the ocean found along the edge of the ocean floor.

19. Mid-ocean Ridges
The mid-ocean ridges form an almost continuous mountain belt that extends from the Arctic Ocean down through the the Atlantic Ocean around Africa into the Indian Ocean and across the Pacific Ocean.
In the Atlantic it is called the mid-Atlantic Ridge and in the Pacific, the Pacific-Antarctica Ridge.

20. Rifts
Running along the middle of the midocean ridges between the rows of parallel mountains are deep crevices or rifts.
Rifts are areas of great earthquake and volcanic activity.

21. Waves Waves are pulses of energy that move through the ocean.
Waves are set in motion by winds, earthquakes and the gravitational pull of the moon.
The most common source of wave movement is the wind blowing across the surface.

22. Movement of Waves
The water in a wave is not moving forward at all. Only the energy moves forward through the water producing one wave after another.
The energy is passed from particle to particle. It is also passed downward. With increasing depth, the motion of the particles decrease. At a certain depth the motion stops. In deep water, there are no waves except those caused by tides and earthquakes.

23. Height of the Waves
Three factors affect the height of waves: wind speed, the length of time the wind blows and the distance the wind blows over the water.
As each of these factors increases, the height of the wave increases.

24. Wave Characteristics The point of the wave is called the crest.
The lowest point of the wave is called the trough.
The horizontal distance between two consecutive crests or troughs is the wavelength.
The vertical distance between a crest and a trough is called the wave height.

25. Wave Period and Frequency
The amount of time it takes consecutive crests or troughs to pass is called the wave period.
The number of crests or troughs passing a given point in a certain wave period is called the wave frequency.
As wave frequency increases, wave length decreases.

26. Swells
Waves stay the same distant apart out in the open ocean. The wavelength is constant. These waves are called swells.

27. Surf
Waves change as they near the shore. They slow down and get closer together. Their wavelength decreases and their increase until they crash forward as breakers. This is called the surf.

28. Undertow
The water then flows back toward the ocean carrying bits of seaweeed, sand and pebbles. The retreating water is called an undertow.

29. Tsunamis Some ocean waves are caused by earthquakes.
Tsunamis have very long wavelengths and are very deep.
They carry a huge amount of energy Which is concentrated in much less water as it nears the shore.
Tsunamis reach heights of 35 meters (an average 10-story building).

30. Currents Water below the surface moves in streams called currents.
Currents are caused by two factors: wind patterns and differences in water density.

31. Surface Currents
Currents caused mainly by wind patterns are called surface currents. These currents have a depth of several hundred meters.
The temperature of a current depends on where it originated, making it either warm or cold.

32. Long-Distance Currents
Surface currents that travel thousands of kilometers are called long-distance currents, such as the Gulf Steam.
The Gulf Stream carries warm water from the southern tip of Florida north along the eastern coast of the United States moving at speeds of 1.5 meters per second.

33. Continuous Currents
All currents form a continuous worldwide pattern of water circulation.
The water in each ocean moves in a large, almost circular pattern.
In the Northern Hemisphere, the currents move clockwise.
In the Southern hemisphere, the currents move counterclockwise.

34. Short- Distance Currents
Short distance currents are usually found near a shoreline where the waves hit at an angle.
When the waves hit the shoreline, the water turns and produces currents that move parallel to the shoreline called longshore currents. Longshore currents move large quantities of sand which deposit in sand bars.

35. Rip Current
If the longshore current cuts an opening in the sandbar the water will return to ocean in a powerful narrow flow called a rip current.
A rip current is a type of undertow.

36. Deep Currents
Deep currents are caused mainly by differences in water density.
The cold, salty water, that is more dense, flowing from the polar regions moves under the less dense water away from the polar regions.
Most deep currents flow in the opposite direction from surface currents.

37. Upwellings
The densest water on Earth lies off the coast of Antarctica.
This water sinks to the ocean floor and flows north. As the Antarctic currents come close to land, the ocean floor rises, forcing these cold currents upward.
These risings, called upwellings, carry rich food from the ocean floor that results in rich fishing grounds near PSpring and Neap Tides
Spring Tides, higher than normal high tides, are produced when the sun, Earth and moon line up or new and full moon phases.
Neap tides, lower than normal high tides, are produced when the sun, Earth and moon are at right angles or first and last quarter moon phases.