1. Physical Oceanography
Chapter 15
Physical Oceanography

2. Chapter 15
Section 15.1
The Oceans

3. Section 15.1 – Learning Goal
I will……….
Identify methods scientists use to study Earth’s oceans.
Discuss the origin and composition of the oceans.
Describe oceans and major seas.

4. Oceanography- The scientific study of the Earth’s oceans.

5. Background – Brief History of Oceanography
The ancient Egyptians were the first to build seafaring ships, around 4000 b.c.
Oceans were used for travel, recreation and to obtain food.

6. Oceans 71 % of Earth’s surface covered by oceans
vast bodies of water affect:
Weather
Climate
Food supplies
Recreation
Global trade
And marine life (such as humpback whales)

7. British Challenger (first research ship)
In the late 1800’s, Challenger used measuring devices to investigate:
ocean currents
water temperature
chemical composition
seafloor sediments
topography

8. SONAR German ship Meteor 1920s– used sonar for first time
Sound Navigation and Ranging
Uses the return time of an echo and the known velocity of sound in water to determine water depth.
Velocity of sound in water is 1500m/s
Velocity of sound in air is 334m/s
Calculation:
Ocean depth= sonar signal and time it returns or echo
Distance to the ocean floor=time x 1500m/s divided by 2.

9. ADVANCED TECHNOLOGY
Satellites (Topex/Poseidon)– monitor ocean’s surface temperature
Submersibles (underwater vessels) – investigates deep trenches
Side-scan sonar (for mapping)- directs sound waves to the seafloor at an angle

10. ORIGIN OF THE OCEANS Were did the water come from?
Earth is about 4.6 billion years old.
Scientists hypothesize that Earth’s water could have originated from 2 sources:
Comets- (dust, rock particles mixed with frozen water and gases)
Gases-water vapor, methane, ammonia
Volcanoes-(water vapor, carbon dioxide and other gasses)

11. DISTRIBUTION OF EARTH’S WATER
97% Oceans (salt water)
3% Fresh water (frozen ice caps, rivers, lakes, underground sources)
Sea Level- is the level of the ocean’s surface.
Affected by:
Melting of ice caps
Tectonic forces
Trivia – avg. global sea level rising 1 -2mm/yr due to melting glaciers

12. THE BLUE PLANET - Earth There are 5 oceans:
71 % of the surface is covered with oceans.
Avg. depth is 3800m
All the oceans are interconnected, continents act as huge islands.
There are 5 oceans:
Pacific Ocean – contains ½ Earth’s seawater
Atlantic Ocean – extends 20,000km
Indian Ocean – located mainly in southern hemisphere
Antarctic Ocean – covered by sea ice
Arctic Ocean – covered by sea ice

13. SEAS Smaller than oceans Mostly landlocked Exp: Aral Sea
Mediterranean Sea – first sea to be mapped by Egyptians, Phoenicians, Greeks, & Romans
Gulf of Mexico
Caribbean Sea
Bering Sea

14. MISCONCEPTIONS
We can usually see through the water in a glass, sink, bucket, or bathtub.
Thus, many people have the impression that water is transparent.
In reality, however, all water absorbs light.

15. Misconceptions
In fact, a layer of ocean water 100m thick absorbs more than 99 percent of light.
This means that the oceans are essentially dark below a depth of 100m.

16. Video- Discovering the seas
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