Ocean Waves,

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Ocean Waves, Currents, and Tides
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What is salinity? What is the most abundant
salt in the ocean?
The amount of dissolved solids in a liquid.
Sodium Chloride
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How do we study the ocean?
satellites and sonar ROVs and Submersables
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Tides
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Tides are...

• Daily changes in the level of ocean water
• Typically, coastal areas have low tides and high
  tides

Photo from http//home.hiwaay.net/krcool/Astro/m
oon/moontides/
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Tides are created by the interaction between the
earth, sun and moon
Photo fromhttp//www.physicalgeography.net/fundam
entals/8r.html
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• The moons relationship to tides was observed,
  but could not be explained until Sir Isaac Newton
  introduced gravity

The Earth spins on its axis and revolves around
the sun. (EarthSun) The moon revolves around the
earth. Which has a greater effect on the
tides-Sun or Moon? Why?
Photo from http//www-groups.dcs.st-and.ac.uk/hi
story/PictDisplay/Newton.html
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• Tides are caused primarily by the gravity between
  Earth and the moon
• They move forward and backward (toward and away
  from shore)

Diagram from http//csep10.phys.utk.edu/astr161/l
ect/time/tides.html
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Diagram from http//www.sfgate.com/getoutside/199
6/jun/tides.html
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Spring tide a tide of increased range that
occurs when sun and moon both impact Earth in the
same direction
Photo from http//www.physicalgeography.net/funda
mentals/8r.html
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http//aspire.cosmic-ray.org/labs/tides/menu_tide.
swf
Neap tides a tide of minimum range that occurs
when the sun and moon work in opposition
Photo from http//www.physicalgeography.net/funda
mentals/8r.html
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Waves!
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• Waves get their energy from WIND
• FETCH the open-water area offshore over
  which waves can be generated by winds
• The Greater the Fetch the larger the waves can
  become

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RED and YELLOW Largest wave heights Lowest
waves where winds fetch is limited by
land Are lowest waves near the equator or the
poles??
Waves
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In deep water, wave action decreases with
depth In shallow water, wave action does not
decrease with depth Crest- highest point of a
wave/Trough- lowest point of a wave Wavelength-
measured from crest to crest or trough to
trough Height- measured from crest to trough
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Why do waves increase their height as they reach
the shore?As waves interact with the ocean floor
they slow down and build up
As waves interact with the ocean floor they slow
down and build up
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Currents
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Types of Currents
Currents
Current A large stream of moving water flowing
through the ocean

• A. Surface Currents
• Caused by winds
• B. Deep Currents
• Causes by density

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What affects the density of water in the ocean?

• Temperature
• Salinity

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Currents and Temperature

• Temperature affects currents
• Equator- Warm-water currents start here (Feeds
  surface currents)
• Poles- Cold-water currents start here
• (Feeds the deep current- the great ocean
  conveyor)

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Coriolis Effect

• The Earths rotation causes wind and surface
  currents to move in curved paths instead of
  straight lines
• Ex. Merry-go-Round- If you roll a ball across a
  spinning Merry-go-Round the ball will curve
  before it reaches the other side

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Northern hemisphere
Clockwise
Southern Hemisphere
Counterclockwise
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Currents and Temperature

• Currents affect temperature
• Sunlight reaches to a depth of about 100 meters
  but warms the water down to about 300 meters.
  Why?
• Surface currents mix the warmer water with the
  cooler water below

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Deep Currents

• Stream like movement of ocean water far below the
  surface
• Deep currents are caused by increasing water
  density

Density the amount of matter in a given space
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Unusual Currents
El Nino El Nino, an abnormal warming of surface
ocean waters
Normally, strong trade winds blow from the east
along the equator, pushing warm water into the
Pacific Ocean. The thermocline layer of water is
the area of transition between the warmer surface
waters and the colder water of the bottom.
An El Nino condition results from weakened trade
winds in the western Pacific Ocean near
Indonesia, allowing piled-up warm water to flow
toward South America.
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Upwelling The movement of cold nutrient rich,
deep ocean water to replace warm water at the
surface. The diagram below shows how upwelling
occurs along the coast of Peru. Because of the
frictional stresses that exist between ocean
layers, surface water is transported at a 90
degree angle to the left of the winds in the
southern hemisphere, 90 degrees to the right of
the winds in the northern hemisphere. This is why
winds blowing northward parallel to the coastline
of Peru "drag" surface water westward away from
shore.