Transcript Physical Oceanography Lesson 1

Physical Oceanography
•UNIT 8
•STANDARDS: NCES 2.1.1, 2.1.3,
2.3.1
•LESSON 1
Lesson Objectives
• In this lesson, you will learn about:
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How scientists study oceans
How the oceans were formed
Where the oceans are located
How seawater and freshwater differ
Water Cycle over Seas
• The water of the sea returns in a cycle. Seawater
evaporates and the water vapor forms clouds that are
blown over land, Precipitation from these clouds soaks into
the ground and flows back to rivers and streams carrying
dissolved minerals with it.
Early Oceanography
• HMS
Challenger
• A little over a hundred years ago, in
1872, a small sailing ship called the
H.M.S. Challenger set sail from
England. Enough material was collected
to fill fifty volumes of information.
• The information collected by the
Challenger was used mostly for shipping
purposes. This voyage was the first
systematic ocean study.
• The next big surge of scientific activity
came during World War II. A knowledge
of the sea was crucial then for military
intelligence.
Modern Oceanography
• German research • First ship to use SONAR
ship Meteor
• Sound Navigation Ranging
• Today
• Side-scan Sonar
• Satellite Topex Poseidon
• Generated 3-D image of the
ocean floor
Origins of the Oceans
• Where did the water
come from?
• Volcanoes
• Comets that impact with the
earth carry water trapped as
ice.
• Meteors also contain water.
• Volcanoes are a main source
of water vapor released into
the atmosphere.
• Volcanoes release H2O, CO2
• Volcanoes continue to
release water vapor today.
Distribution of the Earth’s Water
• Distribution • Oceans contain 97% of the earth’s
water.
• 3% is found in ice caps, rivers, lakes,
and underground.
• Global sea levels have risen and fallen
dependent on the amount of water
trapped as ice.
• Plate tectonics also cause the sea floor
to rise and fall and affects the sea level.
Major Oceans (1 Ocean System)
• 5 Oceans
• The Pacific Ocean
– Covers the largest area—more than half of the
water in the world
• The Indian Ocean
– Third largest ocean in the world
• The Atlantic Ocean
– Shallowest of the three largest oceans (3.93
km, 12880 feet)
– Area of sea-floor spreading
• The Arctic Ocean
– The smallest in area of the oceans
– Has a very shallow sea floor
• The Southern Ocean (Antarctic)
– Mostly covered with ice
The Blue Planet
• Oceanographic studies, as
well as satellite photo of
earth, have shown us that our
planet Earth is a “planet of
water.”
• Over 71% (about threefourths of the earth’s surface)
is covered by water.
• Water covers 61% of the
Northern Hemisphere and
81% of the Southern
Hemisphere.
Seas
• Seas are smaller than
oceans
• Seas are partially or
mostly landlocked.
• *All seas and oceans
belong to the 1 world
ocean. Their water is
intermixed.
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Mediterranean
Caribbean Sea
Bering Sea
Red Sea
Black Sea
Section Review 8.1.1
• What is oceanography?
• What was learned from the Challenger
expedition?
• What is sonar?
• Where did the water in the early oceans
come from?
Seawater: (96.5% water 3.5% salts)
• Properties of
seawater
• Salinity
• Composition
• Ocean water is different from water
in lakes and streams. Ocean water
tastes salty.
 Saltiness- the major ingredient is
sodium chloride.
 More than half of the minerals found
on land are also dissolved in ocean
water.
• O2- ocean water also contains many
dissolved gases. The most important
gases are oxygen and carbon dioxide.
Salinity: amount of dissolved salts
• Variations
• Salinity based on evaporation. Highest
at equator, then tropics, subtropics and
finally poles. (warm to cold water)
• Sources
• Volcanic ash and the erosion of minerals
from the land are sources.
• Freezing Point
• Seawater (salt water) has a lower
freezing point than fresh water because
of the dissolved salts. Salt water freezes
near –2oC.
Ocean Layering
• Temperatures
• Ocean temperatures are
dependent on location and
depth from the surface.
• Closer to equator = warmer
• Closer to surface = warmer
• Surface depth about 100 m
• Thermocline-transition layer
• Bottom layer-coldest water
and also the deepest
Temperature Summary
• Two primary factors determine ocean water temperature:
– The latitude of the body of water (the distance north or south of the
equator).
– The depth of the water.
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The winds of the earth drive warm ocean currents of the equator
toward the North and South Poles.
• From the surface of the water down to about 91 meters (300 ft), the
water temperature remains constant.
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• From 91 meters to approximately 2,700 meters (3,000 ft), the
temperature drops as the depth increases.
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• Below 2,700 meters, the temperature is again constant. There is very
little heat here. The temperature is very close to the freezing point of
salt water (-2.2° C or 28° F)
Section Review 8.1.2
• What is the most abundant salt in seawater?
• How do salts enter the oceans?
• The salinity is higher in the tropics when
compared to the polar regions, why?
• Explain why salt is used to de-ice roads