Download Section 22.3

UNIT SEVEN: Earth’s Water
 Chapter 21 Water and Solutions
 Chapter 22 Water Systems
 Chapter 23 How Water Shapes the
Land
Chapter Twenty-Two: Water Systems
 22.1 Water on Earth’s Surface
 22.2 The Water Cycle
 22.3 Oceans
Chapter 22.3 Learning Goals
 Discuss the effects of temperature and
salinity on Earth’s oceans.
 Distinguish features of the ocean floor.
 Compare and contrast the effects of surface
currents and deep ocean currents.
22.3 Oceans
 Ocean water is about 3.5
percent salt.
 The word salinity is a
measure of the dissolved
salts in water.
 Most of the salt in ocean
water is sodium chloride.
22.3 Oceans
 In some places,
special ponds
called salt
evaporation ponds
harvest salt from
the ocean.
22.3 Oceans
The salt in the oceans comes from:
1. minerals in the ocean floor,
2. gases released by volcanoes, and
3. rivers that carry dissolved minerals
out to sea.
Can you name Earth’s five oceans?
22.3 Importance of oceans
 Oceans are an important
source of water for the
water cycle.
 Oceans spread energy
and heat from the hot
equator to the colder
poles.
 Phytoplankton produce
most of the oxygen in
the atmosphere.
22.3 Oceans and Earth’s climate
 The oceans are able to store heat energy.
 The water on Earth prevents the planet from
getting too hot or too cold.
22.3 Oceans and Earth’s climate
 The climates on the coastline are milder than
they are inland because ocean-warmed air
masses move over the oceans toward the
land.
22.3 Oceans and Earth’s climate
 The climates on
coastlines are milder
than they are inland
because oceanwarmed wind and air
masses move over
the oceans toward
the land.
22.3 Surface currents and gyres
 The Sun’s unequal
heating of Earth and
the Coriolis effect
cause permanent
global wind patterns.
 Surface ocean
currents to form large
rotating systems
called gyres.
22.3 Surface currents and gyres
 One well-known
current is the Gulf
Stream.
 Europe has mild
winters due to both
prevailing westerlies
and the heat energy of
the Gulf Stream.
22.3 Deep ocean currents
 Deep ocean currents move below the surface
of the ocean.
 They are slower than surface ocean currents.
22.3 The ocean floor
 Many of the important features of the oceans
are hidden in deep water.
 The continental margin is the region around
continents that includes the:
 continental shelf,
 continental slope, and
 continental rise.
22.3 The continental shelf
 Sand drifting down the steep face of a
continental shelf cuts into the shelf just like
streams cut into valleys.
22.3 Features of the ocean floor
 Maps can show the
location of the
continental shelf.
 The true ocean floor
is called the abyssal
plain.
 It is flat and smooth
because a thick
layer of sediment
covers its features.
22.3 The deep ocean floor
 A barrier island is a
low, sandy island that
lies parallel to the
shoreline.
 A bank is a low, flat
region on the
continental shelf.
 A seamount is a
steep-sided mountain
that rises from the
ocean floor.
22.3 The deep ocean floor
 A guyot is a seamount
that has eroded so that
it has a flat top and is
underwater.
 Mid-ocean ridges mark
places where two
tectonic plates are
separating and new
ocean crust is being
made.
 Deep-ocean trenches are the deepest parts of the
ocean.
Investigation 22C
Global Winds and Ocean Currents
 Key Question:
 How do temperature and salinity cause ocean
layering?
Rip Currents
 More than 80% of
water rescues
performed by surf
beach lifeguards are
due to rip currents.
 Rip currents are sometimes called riptides, or
undertow. Learn why these two terms are
misleading.