Download Earth`s Oceans

Oceans
Cues
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World Oceans
Seas
Properties of Ocean Water
Elements
Salinity
Sources
Salinity Levels
Gases
Temperature
Ocean Floor
Edges of Continents
Study the Ocean Floor
Oceanographer
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.
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.
Seas
A
sea is a part of an ocean that is
nearly surrounded by water.
 The Mediterranean, Arctic and Black
Sea are really part of the Atlantic
Ocean.
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 have been found in the
ocean.
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.
Salinity
 Salinity
describes the amount of
dissolved water in the ocean.
 Salinity is expressed in parts per
thousand.
 The salinity level of the ocean is
expressed in parts per thousand.
 The average salinity of ocean is 35
parts per thousand.
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.
 As waves pound the shoreline, they
dissolve salts from the rocks.
Salinity Levels
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The salinity is lower in areas where freshwater
rivers run into the ocean. Salinity levels are also
affected by animals such as clams and oysters
that use calcium salts to build their shells. They
remove salt from the water.
In warm ocean areas where there is little rainfall
and much evaporation, the amount of dissolved
salts is much greater. In polar regions, the
salinity levels are high because temperatures are
cold enough for ocean water to freeze. Pure
water is removed and salts are left behind.
Gases in Ocean Water
 The
most abundant gases in ocean
water are nitrogen, carbon dioxide
and oxygen.
 The amounts of these elements vary
with depth. They are more abundant
at the ocean’s surface where sunlight
causes more plant life.
Temperature of Ocean Water
 Warm
water holds less dissolved gas
than cold water.
 When ocean water is cold, like in
polar regions, it sinks and carries
oxygen rich water to the ocean
depths.
 As a result, fish and other animals
can live in deep parts of the ocean.
Temperature of Ocean Water
Sun is the major
source of heat for
the ocean.
 Motions of the
ocean, such as
waves and
currents, mix the
surface water and
transfer the heat
downward.
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The Ocean Floor
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The topography of the ocean floor is
different from the topography of the
continents
The Ocean Floor
The ocean floor has higher mountains,
deeper canyons, and larger flatter plains.
Earthquakes occur more often.
 The rocks are very different.
 The crust is thinner.
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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.
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Studying the Ocean Floor
In 1872, the first expedition to explore the
ocean began when the Challenger sailed
from England.
 Scientists used wire to measure the ocean
depth.
 Scientists aboard used nets to collect
animals and plants from the ocean floor.
 Special thermometers measured the
temperature. Samples of water were
collected.
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Present Oceanographers
 Today
oceanographers have modern
instruments.
 Underwater cameras provide pictures
of the ocean floor. Corers bring up
samples of med and sand from the
ocean bottom.
 Bathyspheres, bathscaphs and other
submersibles are able to dive deep
under the surface to explore
Mapping the Ocean Floor
 One
of the most important goals is to
map the ocean floor. This is done by
indirect methods such as echo
sounding, radar, sonar and
seismographic surveys.
Echo Soundings
All of these methods are based on the
same principles. Energy waves are sent
down to the floor are reflected and return
to the surface, where they are recorded.
 Knowing the speed of sound, 1500 m per
second, oceanographers can determine
the depth.
 The most complete picture was gathered
from information from a satellite, the
Seasat, launched in 1978
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Assignment
 Section
10.1 questions 1-6