Download section 7.1 - introduction to oceans

Water and Weather
Chapter Seven: Oceans
• 7.1 Introduction to Oceans
• 7.2 Waves
• 7.3 Shallow Marine Environments
• 7.4 The Ocean Floor
Investigation 7A
Global Winds and Ocean Currents
• How do temperature and
salinity cause ocean layering?
7.1 Introduction to Oceans
• 97% of Earth’s water is in
oceans. Only 3% is
freshwater.
• Ocean water is about 3.5% salt
and most of that salt is sodium
chloride (table salt.)
• Salinity is the saltiness of a
body of water.
7.1 Introduction to Oceans
• In some places,
special ponds
called salt
evaporation ponds
harvest salt from
the ocean.
7.1 Introduction to Oceans
• The salt in the oceans comes from:
– minerals in the ocean floor
– gases released by volcanoes, and
– rivers that carry dissolved minerals out
to sea.
Can you name Earth’s five oceans?
7.1 Importance of oceans
• Oceans are an important
source of water for the
water cycle.
• Oceans help maintain
Earth’s heat balance and
keep temperatures from
being extreme.
• Phytoplankton in oceans
produce most of the oxygen
in the atmosphere.
7.1 Earth’s energy
• Water changes temperature slowly due to
a high specific heat. This allows oceans
to store heat energy.
• Heat energy is spread throughout Earth
by ocean currents.
7.1 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.
7.1 Surface currents and gyres
• Surface ocean currents are
caused by wind & temperature
variations.
• The Gulf Stream is an example
of a surface ocean current.
• Gyres spin clockwise in the
Northern Hemisphere.
• Gyres curve as they flow away
from the equator because of the
Coriolis Effect.
7.1 Oceans and Earth’s climate
• Deep ocean currents move below the surface of
the ocean. They are slower than surface ocean
currents.
• Deep ocean currents are caused by
differences in temperature and salinity.
7.1 Deep Ocean Currents
• Thermohaline is another name for
deep ocean currents.
• Salinity, temperature, and rate of
evaporation all affect the density of
seawater.
• Denser water causes deep ocean
currents.