Lesson 11
The World’s Oceans
• EQ: How does the
composition and topography
of earth’s oceans vary by
location?
Ocean Water Chemistry- Questions
you will be able to answer
How salty is ocean
water?
How do the conditions
in the ocean change
with depth?
How did the ocean
form and how is it
currently divided?
Describe one factor
that increases the
salinity of seawater &
one factor that
decreases salinity.
How Did the Oceans Form?
• About 4 billion years ago, the
Earth cooled enough for water
vapor to condense.
• The water began to fall as rain.
• The rain filled the deeper levels of
Earth’s surface and the first
oceans began to form.
Divisions of the Global Oceans
• Pacific- the largest ocean; getting smaller
• Atlantic- the second largest; getting larger
• Indian- third largest;
• Southern- located along the border of
Antarctica
• Arctic- smallest ocean; most
oceanographers consider it as an
extension of the Pacific, Atlantic, and
Indian Oceans
Locate the Oceans
• With your group in PENCIL (in case you
mess up), label these on your map:
– Pacific Ocean
– Atlantic Ocean
– Indian Ocean
– Arctic Ocean
– Southern Ocean aka Antarctic Ocean
Arctic Ocean
Arctic Ocean
Arctic Ocean
North
Atlantic Ocean
Pacific
Ocean
Pacific Ocean
South
Atlantic Ocean
Indian Ocean
Southern Ocean
Southern Ocean
Southern Ocean
Warm Up February 11th
Write name, date, & period at the
top of your sheet.
1.What is the average salinity of
the ocean?
2.How is the Dead Sea different
from other bodies of water?
Describe Where your Ocean is
1. Each group will be given an ocean. Write it
on the back of your oceans paper so that you
remember.
2. You must describe where your ocean is in
relation to the continents.
It is East of_______. It is west of
_________It is north of _______. It is
south of________.
3. Write your answers on the bottom of your
map
Location of the World’s Oceans
• The Pacific Ocean is the largest ocean. It is
bordered by North America, South America,
Asia, Australia, and Antarctica
• The Atlantic is the second largest ocean. It is
bordered by N. America, S. America, Africa,
Europe, and Antarctica.
• The third largest ocean is the Indian Ocean. It
lies between the countries of India, Pakistan,
Australia, and the continents of Africa and
Antarctica.
Characteristics of Ocean Water
• Ocean water is salty
• full of dissolved solids
• Climate affects salinity
• Water movement affects salinity
• Temperate zones
• Surface temperature Changes
Why is the Ocean Salty?
• Most of the salt found in oceans is
sodium chloride (table salt).
Where does the salt come
from?
• solid materials
come from volcanic
eruptions
• hot springs
• ocean waves
crashing against
rocks
Where does the salt come
from?
• Also, during the
water cycle, fresh
water from the
ocean is evaporated
leaving only the
salts behind.
Where does the salt come
from?
• Salts have been added to the oceans
for billions of years by running waters
(rivers, streams) which dissolve
various minerals, and then dump the
water into the oceans.
How Salty is the Ocean?
• Salinity- the measure of the amount of
dissolved salts in a given amount of water
• The average amount of salt in ocean
water is about 3.5% or 35 grams of salt
per one kilogram (1000 g) of water
• Ocean water carries many different
dissolved salts
Solids substances dissolved in
ocean
• Main substance dissolved in ocean water:
sodium chloride aka table salt
• Other solid substances dissolved in ocean:
sulfate, magnesium, calcium, and potassium.
• Where do these dissolved solid substances
come from?
– rivers, streams, rocks from the shore, volcanoes
and underwater hot springs.
• The concentration of all the dissolved
substances in sea water is about 3.5%.
Gases Dissolved in the Oceans
• The oceans also holds 2 dissolved gases,
•
1. oxygen
2. carbon dioxide
Why are these gases important?
– Marine life such as fish need dissolved oxygen in
sea water to live.
• (Most oxygen in oceans come from the
atmosphere because it is closer to the surface of
the water).
– Sea plants such as seaweeds need carbon dioxide
to survive.
Factors Effecting Salinity
Salinity- the measure of the amount of dissolved
salts in a given amount of water.
• Evaporation
• Precipitation
• Freezing
• Rivers dumping water into oceans
• Climate
• Location
• water movement
Increasing and Decreasing
Salinity
–evaporation•increases salinity because only
freshwater is evaporated.
Therefore, salt is left behind.
–freezing•only freshwater freezes, so salt is
left behind, causing an increase in
salinity
Increasing and Decreasing
Salinity
• precipitation– decreases salinity because
all forms of
precipitation are freshwater.
• rivers dumping water into oceans– causes decreasing salinity, because rivers are
freshwater, and the amount of salt stays the same
as freshwater is added.
Climate Affects Salinity
• Some parts of the ocean are saltier than other
parts of the ocean.
– Coastal waters in places with hotter, drier
climates have a higher salinity. (More
evaporation because it is hotter, so less
water, more salt).
– Coastal waters in places with cooler, more
humid climates have a lower salinity (Less
heat, so less evaporation, more water is left
in ocean).
Climate Affects Salinity
Along which coast would salinity be
higher? Lower?
Location Affects Salinity
• Also: Coastal waters in general have less
salinity because more fresh water from rivers
run into the oceans in these areas.
Water Movement Affects Salinity
• Some parts of the ocean (bays, seas,
gulfs) move less than other parts.
• Also, some parts of the open ocean that
do not have currents run through them
can be slow moving.
• Slower-moving areas of water develop
high salinity.
Water Movement Affects Salinity
Water Movement Affects Salinity
For the following chart on the next
2 slides (on the last page of your
notes), fill in the chart using your
notes from this Power Point.
Factors
Effecting
Salinity
Location
Climate
Movement
Evaporation
Precipitation
Freezing
HIGHER
Salinity
LOWER
Salinity
Explain
Factors
Effecting
Salinity
Evaporation
Precipitation
Freezing
HIGHER
Salinity
LOWER
Salinity
Explain
Factors
Effecting
Salinity
Location
Climate
Movement
HIGHER
Salinity
LOWER
Salinity
Explain
If you were to go scuba diving…
you would experience….
• The Temperature decreases as you go
deeper.
• Pressure increases with as you go deeper
Interesting Fact:
• You could only dive to a depth of 40 m.
Any further depth will cause the lungs to
collapse!
Temperate Zones
• Temperature of ocean water decreases
with depth.
• Water in the ocean is divided into three
layers by temperate.
• Top layer (surface zone)
• Middle layer (thermocline zone)
• Bottom layer (deep zone)
Temperature Changes
• Temperature in the surface zones vary
with latitude and the time of the year.
• Parts of the ocean along the equator are
warm because it receives more direct
sunlight per year than areas closer to the
poles.